Climate change mitigation

Coal, oil, and natural gas remain the primary global energy sources even as renewables have begun rapidly increasing.

Climate change mitigation consist of human actions to reduce greenhouse gas emissions or to enhance carbon sinks that absorb greenhouse gases from the atmosphere. Climate change is mostly caused by the greenhouse gases that are released when burning coal, oil, and gas. Fossil fuel use can be reduced through energy conservation and by switching to clean energy sources. Wind power and solar photovoltaics (PV) are increasingly becoming cheaper than fossil fuels, though these require energy storage and improved electrical grids. As low-emission energy is deployed at large scale, transport and heating can shift to these mostly electric sources. Climate change may also be mitigated by reducing greenhouse gas emissions from agriculture, forest-management (by reforestation and preservation), waste management, buildings, and industrial systems.

Methane emissions, which have a high short-term impact, can be targeted by reductions in dairy products and meat consumption. In addition to reducing emissions, expensive technologies can remove carbon dioxide from the atmosphere, climate engineering may be needed to reduce heating of the atmosphere, and adaptation will be needed to adjust to climate change.

Global greenhouse gas emission scenarios, based on policies and pledges as of 11/21

Almost all countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC). The ultimate objective of the UNFCCC is to stabilize atmospheric concentrations of GHGs at a level that would prevent dangerous human interference with the climate system. In 2010, parties to the UNFCCC agreed that future global warming should be limited to below 2 °C (3.6 °F) relative to the pre-industrial level. With the Paris Agreement of 2015, this was confirmed.

Current policies are estimated to produce global warming of about 2.7 °C by 2100, well above the 2 °C goal. Political and economic responses to date include forms of carbon pricing by carbon taxes and carbon emission trading, reductions of fossil fuel subsidies, making national promises and laws, clean energy subsidies, simplified regulations for the integration of low-carbon energy, and divestment from fossil fuel finance.

Overview

Definition

The IPCC Sixth Assessment Report defines climate change mitigation as "A human intervention to reduce emissions or enhance the sinks of greenhouse gases".

Goals

The overall goal of climate change mitigation is: "to preserve a biosphere which can sustain human civilization and the complex of ecosystem services which surround and support it. This means reducing anthropogenic greenhouse gas emissions towards net zero to limit the warming, with global goals agreed in the Paris Agreement."

Co-benefits

There are also co-benefits of climate change mitigation. For example, in the transport sector, possible co-benefits of mitigation strategies include: air quality improvements, health benefits, equitable access to transportation services, reduced traffic congestion, and reduced material demand. The increased use of green and blue infrastructure can reduce the urban heat island effect and heat stress on people, which will improve the mental and physical health of urban dwellers. Climate change mitigation might also lead to less inequality and poverty.

Risks and adverse effects

The beneficial or adverse impacts of deploying climate-change mitigation measures are highly context-specific and also depend on the scale. There can even be risks, adverse effects or trade-offs from mitigation measures, for example in the area of land-based mitigation measures. Another example can be found in the area of renewable energies: mining for materials needed for renewable energy production can increase threats to conservation areas. There also is research into ways to recycle solar panels (including the emerging perovskite solar cells) as recycling solar panels could be important for sustainability, reduce electronic waste and create a source for materials that would otherwise need to be mined.

However, forms of discourses about risk and adverse effects of mitigation measures may "often lead to deadlock or a sense that there are intractable obstacles to taking action".

Approaches

Climate change mitigation is all about reducing and recapturing greenhouse gas emissions. The approaches that are being used fall into the following categories:

• Clean energy: sustainable energy and sustainable transport
• Energy conservation: efficient energy use and energy conservation
• Agriculture and industry: sustainable agriculture and green industrial policy
• Carbon sequestration: carbon dioxide removal and carbon sequestration

This section is an excerpt from Climate change § Reducing and recapturing emissions.[edit]

Climate change can be mitigated by reducing the rate at which greenhouse gases are emitted into the atmosphere, and by increasing the rate at which carbon dioxide is removed from the atmosphere. In order to limit global warming to less than 1.5 °C global greenhouse gas emissions needs to be net-zero by 2050, or by 2070 with a 2 °C target. This requires far-reaching, systemic changes on an unprecedented scale in energy, land, cities, transport, buildings, and industry.

The United Nations Environment Programme estimates that countries need to triple their pledges under the Paris Agreement within the next decade to limit global warming to 2 °C. An even greater level of reduction is required to meet the 1.5 °C goal. With pledges made under the Paris Agreement as of October 2021, global warming would still have a 66% chance of reaching about 2.7 °C (range: 2.2–3.2 °C) by the end of the century. Globally, limiting warming to 2 °C may result in higher economic benefits than economic costs.

Although there is no single pathway to limit global warming to 1.5 or 2 °C, most scenarios and strategies see a major increase in the use of renewable energy in combination with increased energy efficiency measures to generate the needed greenhouse gas reductions. To reduce pressures on ecosystems and enhance their carbon sequestration capabilities, changes would also be necessary in agriculture and forestry, such as preventing deforestation and restoring natural ecosystems by reforestation.

Other approaches to mitigating climate change have a higher level of risk. Scenarios that limit global warming to 1.5 °C typically project the large-scale use of carbon dioxide removal methods over the 21st century. There are concerns, though, about over-reliance on these technologies, and environmental impacts. Solar radiation modification (SRM) is also a possible supplement to deep reductions in emissions. However, SRM raises significant ethical and legal concerns, and the risks are imperfectly understood.

If CO₂ emissions would only stop growing this would not stabilize the GHG concentration in the atmosphere.

Stabilizing the atmospheric concentration of CO₂ at a constant level would require emissions to be effectively eliminated.

Drivers of global warming

Main article: Attribution of recent climate change

2020 Worldwide CO2 emissions (by region, per capita); variwide diagram

The drivers of the recent temperature rise are:

• Greenhouse gases (see: Greenhouse gas, Greenhouse gas emissions, Greenhouse effect, and Carbon dioxide in Earth's atmosphere)
• Land surface changes
• Aerosols and clouds
• Climate change feedback (see Climate change feedback and Climate sensitivity)
• Solar and volcanic activity (see solar activity and climate)

Greenhouse gas emissions

This section is an excerpt from Greenhouse gas emissions.[edit]

Annual carbon dioxide emissions per person (height of vertical bars) and per country (area of vertical bars) of the fifteen high-emitting countries

Greenhouse gas (GHG) emissions from human activities intensify the greenhouse effect. This contributes to climate change. Carbon dioxide (CO₂), from burning fossil fuels such as coal, oil, and natural gas, is one of the most important factors in causing climate change. The largest emitters are China followed by the United States. The United States has higher emissions per capita. The main producers fueling the emissions globally are large oil and gas companies. Emissions from human activities have increased atmospheric carbon dioxide by about 50% over pre-industrial levels. The growing levels of emissions have varied, but have been consistent among all greenhouse gases. Emissions in the 2010s averaged 56 billion tons a year, higher than any decade before. Total cumulative emissions from 1870 to 2017 were 425±20 GtC (1558 GtCO₂) from fossil fuels and industry, and 180±60 GtC (660 GtCO₂) from land use change. Land-use change, such as deforestation, caused about 31% of cumulative emissions over 1870–2017, coal 32%, oil 25%, and gas 10%.

Carbon dioxide (CO₂) is the main greenhouse gas resulting from human activities. It accounts for more than half of warming. Methane (CH₄) emissions have almost the same short-term impact. Nitrous oxide (N₂O) and fluorinated gases (F-gases) play a lesser role in comparison. Emissions of carbon dioxide, methane and nitrous oxide in 2023 were all higher than ever before.

Electricity generation, heat and transport are major emitters; overall energy is responsible for around 73% of emissions. Deforestation and other changes in land use also emit carbon dioxide and methane. The largest source of anthropogenic methane emissions is agriculture, closely followed by gas venting and fugitive emissions from the fossil-fuel industry. The largest agricultural methane source is livestock. Agricultural soils emit nitrous oxide partly due to fertilizers. Similarly, fluorinated gases from refrigerants play an outsized role in total human emissions.

Needed emissions cuts

If emissions remain on the current level of 42 GtCO₂, the carbon budget for 1.5 °C could be exhausted in 2028.

In 2022, the Intergovernmental Panel on Climate Change (IPCC) released its Sixth Assessment Report on climate change, warning that greenhouse gas emissions must peak before 2025 at the latest and decline 43% by 2030, in order to likely limit global warming to 1.5°C (2.7°F). Secretary-general of the United Nations, António Guterres, clarified that for this "Main emitters must drastically cut emissions starting this year".

In 2019, the emissions gap report of the United Nations Environment Programme for limiting warming to 1.5 °C GHG said that emissions should be cut from the level of 2020 by 76% by 2030.

In 2018, the Special Report on Global Warming of 1.5 °C said that limiting warming to 1.5 °C (2.7 °F) would require decreasing net CO₂ emissions by around 45% by 2030 from the level of 2010 and reach net zero by 2050. For limiting global warming to below 2 °C (3.6 °F), CO₂ emissions should decline by 25% by 2030 and by 100% by 2075. Non-CO₂ emissions need to be strongly reduced at similar levels in both scenarios.

Energy systems

Main article: Energy transition

There are specific, individual mitigation options in energy systems. This is complimentary to mitigation options in other sectors that all use energy.

Rapid and deep reductions in the CO2 and GHG emissions from energy system are needed to limit global warming to well below 2°C.

Fossil fuel substitution

Main article: Fossil fuel phase-out

File:IPCC AR6 WG3 SPM-50 Mitigation Options.png

A comparison of various climate change mitigation options by 2030 shows the highest potential at cheapest cost for wind and solar energy.

As most greenhouse gas emissions are due to fossil fuels, rapidly phasing out oil, gas and coal is critical. In a system based on fossil fuels, demand is expected to double until 2050. Switching to renewable energy combined with the electrification of transport and heating can lower the primary energy demand significantly. Currently, less than 20% of energy is used as electricity.

A global transition to sustainable energy across all sectors is feasible well before 2050. With dropping prices for wind and solar energy as well as storage, the transition no longer depends on economic viability but is considered as a question of political will .The sustainable energy system is more efficient and cost effective than the existing system. Investors in fossil fuels face a growing risk of stranded assets.

Renewable energies

Main article: Renewable energy

See also: Low-carbon economy, Renewable energy commercialization, and Renewable energy debate

Wind and sun can be sources for large amounts of low-carbon energy at competitive production costs. But even in combination, generation of variable renewable energy fluctuates a lot. This can be tackled by extending grids over large areas with a sufficient capacity or by using energy storage (see also: forms of grid energy storage) and by other means. Load management of industrial energy consumption can help to balance the production of renewable energy production and its demand. Electricity production by biogas and hydro power can follow the energy demand. Both can be driven by variable energy prices.

The deployment of renewable energy would have to be accelerated six-fold though to stay under the 2 °C target.

Global primary energy demand exceeded 161,000 TWh in 2018. This refers to electricity, transport and heating including all losses. In transport and electricity production, fossil fuel usage has a low efficiency of less than 50%. Large amounts of heat in power plants and in motors of vehicles are wasted. The actual amount of energy consumed is significantly lower at 116,000 TWh.

The competitiveness of renewable energy is a key to a rapid deployment. In 2020, onshore wind and solar photovoltaics were the cheapest source for new bulk electricity generation in many regions. Storage requirements cause additional costs. A carbon price can increase the competitiveness of renewable energy.

	Installed TWp	Growth TW/yr	Production per installed capacity*	Energy TWh/yr*	Growth TWh/yr*	Levelized cost US¢/KWh	Av. auction prices US¢/KWh	Cost development 2010–2019
Solar PV	0.580	0.098	13%	549	123	6.8	3.9	−82%
Solar CSP	0.006	0.0006	13%	6.3	0.5	18.2	7.5	−47%
Wind Offshore	0.028	0.0045	33%	68	11.5	11.5	8.2	−30%
Wind Onshore	0.594	0.05	25%	1194	118	5.3	4.3	−38%
Hydro	1.310	0.013	38%	4267	90	4.7		+27%
Bioenergy	0.12	0.006	51%	522	27	6.6		−13%
Geothermal	0.014	0.00007	74%	13.9	0.7	7.3		+49%

^* = 2018. All other values for 2019.

This section is an excerpt from Renewable energy.[edit]

Examples of renewable energy options: concentrated solar power with molten salt heat storage in Spain; wind energy in South Africa; the Three Gorges Dam on the Yangtze River in China; biomass energy plant in Scotland.

Renewable energy (or green energy, low-carbon energy) is energy from renewable natural resources that are replenished on a human timescale. Using renewable energy technologies helps with climate change mitigation, energy security, and also has some economic benefits. Commonly used renewable energy types include solar energy, wind power, hydropower, bioenergy and geothermal power. Renewable energy installations can be large or small. They are suited for urban as well as rural areas. Renewable energy is often deployed together with further electrification. This has several benefits: electricity can move heat or objects efficiently, and is clean at the point of consumption. Variable renewable energy sources are those that have a fluctuating nature, such as wind power and solar power. In contrast, controllable renewable energy sources include dammed hydroelectricity, bioenergy, or geothermal power.

Other low-carbon energy sources

The 150 MW Andasol solar power station is a commercial parabolic trough solar thermal power plant, located in Spain. The Andasol plant uses tanks of molten salt to store solar energy so that it can continue generating electricity for 7.5 hours after the sun has stopped shining.

The Shepherds Flat Wind Farm is an 845 megawatt (MW) nameplate capacity, wind farm in the US state of Oregon, each turbine is a nameplate 2 or 2.5 MW electricity generator.

The 22,500 MW nameplate capacity Three Gorges Dam in the People's Republic of China, the largest hydroelectric power station in the world

Natural gas for fossil fuel switching

This section is an excerpt from Sustainable energy § Fossil fuel switching and mitigation.[edit]

Switching from coal to natural gas has advantages in terms of sustainability. For a given unit of energy produced, the life-cycle greenhouse-gas emissions of natural gas are around 40 times the emissions of wind or nuclear energy but are much less than coal. Burning natural gas produces around half the emissions of coal when used to generate electricity and around two-thirds the emissions of coal when used to produce heat. Natural gas combustion also produces less air pollution than coal. However, natural gas is a potent greenhouse gas in itself, and leaks during extraction and transportation can negate the advantages of switching away from coal. The technology to curb methane leaks is widely available but it is not always used.

Switching from coal to natural gas reduces emissions in the short term and thus contributes to climate change mitigation. However, in the long term it does not provide a path to net-zero emissions. Developing natural gas infrastructure risks carbon lock-in and stranded assets, where new fossil infrastructure either commits to decades of carbon emissions, or has to be written off before it makes a profit.

Nuclear power

Main article: Nuclear power

A comparison of price changes for energy from nuclear fission and from other sources

In most 1.5 °C pathways of the Intergovernmental Panel on Climate Change's Special Report on Global Warming of 1.5 °C the share of nuclear power is increased. The main advantage of nuclear energy is the ability to deliver large amounts of base load when renewable energy is not available.

On the other hand, environmental and security risks could outweigh the benefits. As of 2019, no country has found a final solution to nuclear waste which can cause future damage and costs over more than one million years. Separated plutonium and enriched uranium could be used for nuclear weapons, which is considered to be a strategical motivation for countries to promote nuclear power. The according risks are comparable to climate change. The Fukushima disaster is estimated to cost taxpayers ~$187 billion and radioactive waste management is estimated to cost the EU ~$250 billion by 2050.

The construction of new nuclear reactors currently takes about 10 years, substantially longer than scaling up the deployment of wind and solar. The largest drawback of nuclear energy is often considered to be the large construction and operating costs when compared to alternatives of sustainable energy sources whose costs are decreasing and which are the fastest-growing source of electricity generation. Nuclear power avoided 2–3% of total global GHG emissions in 2021. China is building a significant number of new power plants, albeit significantly fewer reactors than originally planned. As of 2019 the cost of extending nuclear power plant lifetimes is competitive with other electricity generation technologies, including new solar and wind projects. New projects are reported to be highly dependent on public subsidies.

Nuclear fusion research, in the form of the ITER and other experimental projects, is underway but fusion energy is not likely to be commercially widespread before 2050.

Carbon neutral and negative fuels

Fossil fuel may be phased-out with carbon-neutral and carbon-negative pipeline and transportation fuels created with power-to-gas and gas to liquids technologies.

Energy efficiency and non-fossil fuel storage

Main article: Energy storage

See also: Hydrogen economy

Wind energy and photovoltaics can deliver large amounts of electric energy but not at any time and place. One approach is the conversation into storable forms of energy. This generally leads to losses in efficiency. A study by Imperial College London calculated the lowest levelized cost of different systems for mid-term and seasonal storage. In 2020, pumped hydro (PHES), compressed air (CAES) and Li-on batteries are most cost effective depending on charging rhythm.

For 2040, a more significant role for Li-on and hydrogen is projected. Li-on batteries are widely used in battery storage power stations and, as of 2020, are starting to be used in vehicle-to-grid storage. They provide a sufficient round-trip efficiency of 75–90 %. However their production can cause environmental problems. Levelized costs for battery storage have drastically fallen to 0.15 US$/KWh

Hydrogen may be useful for seasonal energy storage. The low efficiency of 30% of the reconversion to electricity must improve dramatically before hydrogen storage can offer the same overall energy efficiency as batteries. Thermal energy in the conversion process can be used for district heating. For the electricity grid a German study estimated high costs of 0.176 €/KWh for reconversion concluding that substituting the electricity grid expansion entirely with hydrogen reconversion systems does not make sense from an economic standpoint. The concept of solar hydrogen is discussed for remote desert projects where grid connections to demand centers are not available. Because it has more energy per unit volume sometimes it may be better to use hydrogen in ammonia.

Super grids

Main article: Super grid

Sketch of a possible super grid. The red squares represent the total surfaces needed for solar collectors of Concentrating Solar Thermal Power (CSP) plants to provide the present electricity demands.

Long-distance power lines help to minimize storage requirements. A continental transmission network can smoothen local variations of wind energy. With a global grid, even photovoltaics could be available all day and night. The strongest high-voltage direct current (HVDC) connections are quoted with losses of only 1.6% per 1000 km with a clear advantage compared to AC. HVDC is currently only used for point-to-point connections. Meshed HVDC grids may be used to connect offshore wind in future.

China has built many HVDC connections within the country and supports the idea of a global, intercontinental grid as a backbone system for the existing national AC grids. A super grid in the US in combination with renewable energy could reduce GHG emissions by 80%.

Smart grid and load management

Main articles: Smart grid and Load management

Instead of expanding grids and storage for more power, electricity demand can be adjusted on the consumer side. This can flatten demand peaks. Traditionally, the energy system has treated consumer demand as fixed. Instead, data systems can combine with advanced software to pro-actively manage demand and respond to energy market prices.

Time of use tariffs are a common way to motivate electricity users to reduce their peak load consumption. On a household level, charging electric vehicles or running heat pumps combined with hot water storage when wind or sun energy are available reduces electricity costs.

Dynamic demand plans have devices passively shut off when stress is sensed on the electrical grid. This method may work very well with thermostats, when power on the grid sags a small amount, a low power temperature setting is automatically selected reducing the load on the grid. Refrigerators or heat pumps can reduce their consumption when clouds pass over solar installations. Consumers need to have a smart meter in order for the utility to calculate credits. Smart Scheduling of activities and processes can adjust demand to fluctuating supply.

Demand response devices can receive all sorts of messages from the grid. The message could be a request to use a low power mode similar to dynamic demand, to shut off entirely during a sudden failure on the grid, or notifications about the current and expected prices for power. This allows electric cars to recharge at the least expensive rates independent of the time of day. Vehicle-to-grid uses a car's battery to supply the grid temporarily. Smart grids could also monitor/control residential devices that are noncritical during periods of peak power consumption, and return their function during nonpeak hours.

Further flexibility techniques by which smart grids can help manage the variability of renewable energy (VRE) and increase efficiency include VRE forecasting methodologies.

Energy conservation and efficiency

Main articles: Efficient energy use and Energy conservation

In the European Investment Bank Climate Survey EU citizens said that in Europe, energy should be the most prioritised area of action against climate change.

Improved energy efficiency in buildings, industrial processes and transportation could reduce the world's energy needs in 2050 by one third, and help control global emissions of greenhouse gases.

Service labels like Energy Star provide information on the energy consumption of products. A procurement toolkit to assist individuals and businesses buy energy efficient products that use low GWP refrigerants was developed by the Sustainable Purchasing Leadership Council. A trial of estimated financial energy cost of refrigerators alongside EU energy-efficiency class (EEEC) labels online found that the approach of labels involves a trade-off between financial considerations and higher cost requirements in effort or time for the product-selection from the many available options – which are often unlabelled and don't have any EEEC-requirement for being bought, used or sold within the EU. Moreover, in this one trial the labeling was ineffective in shifting purchases towards more sustainable options. Beyond establishing higher efficiency of household appliances such as fridges and washing machines (or smaller ovens and non-use of drying machines), facilitating (less or) greener travel, installation of heat pumps, energy audits, and reducing room heating are also important. Energy efficiency of appliances as well as cooking techniques/choices have a substantial impact on GHGs from foods. In order for consumers to efficiently conserve energy, they – especially tenants – may need to have access to the (up to real-time) data of their electricity use and knowledge about efficient conservation options. Moreover, the most effective energy conservation options may not be in households but the industry or e.g. public venues.

The cogeneration of electric energy and district heat also improves efficiency.

Head of the IEA declared the failure by governments and businesses to accelerate energy efficiency efforts as "inexplicable", with IEA analysis showing that greater efficiency could be achieved with existing technologies and measures.

Carbon dioxide removal

About 58% of CO₂ emissions have been absorbed by carbon sinks, including plant growth, soil uptake, and ocean uptake (2020 Global Carbon Budget).

World protected area map with total percentage of each country under protection, where countries in lighter colors have more protected land

This section is an excerpt from Carbon dioxide removal.[edit]

Planting trees is a nature-based way to temporarily remove carbon dioxide from the atmosphere.

Carbon dioxide removal (CDR) is a process in which carbon dioxide (CO₂) is removed from the atmosphere by deliberate human activities and durably stored in geological, terrestrial, or ocean reservoirs, or in products. This process is also known as carbon removal, greenhouse gas removal or negative emissions. CDR is more and more often integrated into climate policy, as an element of climate change mitigation strategies. Achieving net zero emissions will require first and foremost deep and sustained cuts in emissions, and then—in addition—the use of CDR ("CDR is what puts the net into net zero emissions"). In the future, CDR may be able to counterbalance emissions that are technically difficult to eliminate, such as some agricultural and industrial emissions.

CDR includes methods that are implemented on land or in aquatic systems. Land-based methods include afforestation, reforestation, agricultural practices that sequester carbon in soils (carbon farming), bioenergy with carbon capture and storage (BECCS), and direct air capture combined with storage. There are also CDR methods that use oceans and other water bodies. Those are called ocean fertilization, ocean alkalinity enhancement, wetland restoration and blue carbon approaches. A detailed analysis needs to be performed to assess how much negative emissions a particular process achieves. This analysis includes life cycle analysis and "monitoring, reporting, and verification" (MRV) of the entire process. Carbon capture and storage (CCS) are not regarded as CDR because CCS does not reduce the amount of carbon dioxide already in the atmosphere.

As of 2023, CDR is estimated to remove around 2 gigatons of CO₂ per year. This is equivalent to about 4% of the greenhouse gases emitted per year by human activities. There is potential to remove and sequester up to 10 gigatons of carbon dioxide per year by using those CDR methods which can be safely and economically deployed now. However, quantifying the exact amount of carbon dioxide removed from the atmosphere by CDR is difficult.

Terminology and scope

Carbon dioxide removal (CDR) is defined as "Anthropogenic activities removing carbon dioxide (CO2) from the atmosphere and durably storing it in geological, terrestrial, or ocean reservoirs, or in products. It includes existing and potential anthropogenic enhancement of biological or geochemical CO2 sinks and direct air carbon dioxide capture and storage (DACCS), but excludes natural CO2 uptake not directly caused by human activities."

The terminology in this area is still evolving. The Sixth IPCC Assessment Report stated in 2022 that the term “geoengineering” (or climate engineering) is used in the literature sometimes for both CDR (carbon dioxide removal) or SRM (Solar radiation management or solar geoengineering) when applied at a planetary scale. In their own report, "CDR and SRM are discussed separately reflecting their very different geophysical characteristics". The terms geoengineering or climate engineering are no longer used in IPCC reports.

Land-based options

Further information: Carbon sequestration § Forestry

Globally, protecting healthy soils and restoring the soil carbon sponge could remove 7.6 billion tons of carbon dioxide from the atmosphere annually, which is more than the annual emissions of the US. Trees capture CO₂ while growing above ground and exuding larger amounts of carbon below ground. Trees contribute to the building of a soil carbon sponge. The carbon formed above ground is released as CO₂ immediately when wood is burned. If dead wood remains untouched, only some of the carbon returns to the atmosphere as decomposition proceeds.

Afforestation

Main article: Afforestation

Afforestation is the establishment of trees where there was previously no tree cover. Scenarios for new plantations covering up to 4000 Mha (6300 x 6300 km) calculate with a cumulative physical carbon biosequestration of more than 900 GtC (2300 GtCO₂) until 2100. However, these are not considered a viable alternative to aggressive emissions reduction, such as the Trillion Tree Campaign, as the plantations would need to be so large, they would eliminate most natural ecosystems or reduce food production.

Preventing deforestation and desertification

Main articles: Deforestation § Control, and Desertification § Countermeasures

Transferring land rights to indigenous inhabitants is argued to efficiently conserve forests.

Avoided deforestation reduces CO₂ emissions at a rate of 1 tonne of CO₂ per $1–5 in opportunity costs from lost agriculture. Cutting trees for woodfuel, the main source of energy for the poor, and clearing forests for agriculture are major drivers of desertification and deforestation.

Transferring rights over land from public domain to its indigenous inhabitants, who have had a stake for millennia in preserving the forests that they depend on, is argued to be a cost-effective strategy to conserve forests. This includes the protection of such rights entitled in existing laws, such as the Forest Rights Act in India, where concessions to land continue to go mostly to powerful companies. The transferring of such rights in China, perhaps the largest land reform in modern times, has been argued to have increased forest cover. Granting title of the land has shown to have two or three times less clearing than even state run parks, notably in the Brazilian Amazon. Even while the largest cause of deforestation in the world's second largest rainforest in the Congo is smallholder agriculture and charcoal production, areas with community concessions have significantly less deforestation as communities are incentivized to manage the land sustainably, even reducing poverty. Conservation methods that exclude humans, called "fortress conservation", and even evict inhabitants from protected areas often lead to more exploitation of the land as the native inhabitants then turn to work for extractive companies to survive.

Preventing permafrost leaks

The global warming induced thawing of the permafrost, which stores about two times the amount of the carbon currently released in the atmosphere, releases the potent greenhouse gas, methane, in a positive feedback cycle that is feared to lead to a tipping point called runaway climate change. While the permafrost is about 14 degrees Fahrenheit (−10 °C), a blanket of snow insulates it from the colder air above which could be 40 degrees below zero Fahrenheit (−40 °C). A method proposed to prevent such a scenario is to bring back large herbivores such as seen in Pleistocene Park, where they keep the ground cooler by reducing snow cover height by about half and eliminating shrubs and thus keeping the ground more exposed to the cold air, although these proposals have also been criticized as likely to be ineffective.

Reforestation

Main article: Reforestation

See also: Desertification

Helping existing roots and tree stumps regrow even in long deforested areas is argued to be more efficient than planting trees. Lack of legal ownership to trees by locals is the biggest obstacle preventing regrowth.

Reforestation is the restocking of existing depleted forests or where there was once recently forests. Reforestation could save at least 1 GtCO₂/year, at an estimated cost of $5–15/tCO₂. With increased intensive agriculture and urbanization, there is an increase in the amount of abandoned farmland. By some estimates, for every acre of original old-growth forest cut down, more than 50 acres of new secondary forests are growing. Promoting regrowth on abandoned farmland could offset years of carbon emissions.

Planting new trees can be expensive, especially for the poor who often live in areas of deforestation, and can be a risky investment as, for example, studies in the Sahel have found that 80 percent of planted trees die within two years. Instead, helping native species sprout naturally is much cheaper and more likely to survive, with even long deforested areas still containing an "underground forest" of living roots and tree stumps that are still able to regenerate. This could include pruning and coppicing the tree to accelerate its growth and that also provides woodfuel, a major source of deforestation. Such practices, called farmer-managed natural regeneration, are centuries old but the biggest obstacle towards implementing natural regrowth of trees are legal ownership of the trees by the state, often as a way of selling such timber rights to business people, leading to seedlings being uprooted by locals who saw them as a liability. Legal aid for locals and pressure to change the law such as in Mali and Niger where ownership of trees to residents was allowed has led to what has been called the largest positive environmental transformation in Africa, with it being possible to discern from space the border between Niger and the more barren land in Nigeria, where the law has not changed.

Proforestation

Main articles: Proforestation and Forest restoration

Proforestation is promoting forests to capture their full ecological potential. Restoring all degraded forests all over the world could capture about 205 GtC (750 GtCO₂). Secondary forests that have regrown in abandoned farmland are found to have less biodiversity than the original old-growth forests and original forests store 60% more carbon than these new forests. Allowing proforestation in some secondary forests will increase their accumulated carbon and biodiversity over time. Strategies for proforestation include rewilding, such as reintroducing apex predators and keystone species as, for example, predators keep the population of herbivores in check (which reduce the biomass of vegetation). Another strategy is establishing wildlife corridors connecting isolated protected areas.

Wetlands

Wet areas such as swamps and peatlands have lower oxygen levels dissolved than in the air and so oxygen reliant decomposition of organic matter by microbes into CO₂ is decreased. Peatland globally covers just 3% of the land's surface but stores up to 550 gigatonnes of carbon, representing 42% of all soil carbon and exceeds the carbon stored in all other vegetation types, including the world's forests. The threat to peatlands include draining the areas for agriculture and cutting down trees for lumber as the trees help hold and fix the peatland. Additionally, peat is often sold for compost. Restoration of degraded peatlands can be done by blocking drainage channels in the peatland, and allowing natural vegetation to recover.

Coastal areas

(A) untrawled seamount and (B) a trawled seamount. Bottom trawling has destroyed many coastal habitats, one of the largest sinks of carbon.

Mangroves, salt marshes and seagrasses make up the majority of the ocean's vegetated habitats but only equal 0.05% of the plant biomass on land and stash carbon 40 times faster than tropical forests. Bottom trawling, dredging for coastal development and fertilizer runoff have damaged coastal habitats. Notably, 85% of oyster reefs globally have been removed in the last two centuries. Oyster reefs clean the water and make other species thrive, thus increasing biomass in that area. In addition, oyster reefs mitigate the effects of climate change by reducing the force of waves from hurricanes and reduce the erosion from rising sea levels.

Ocean-based options

Main articles: Blue carbon and Ocean storage of carbon dioxide

Ocean-based mitigation system include ocean alkalinity enhancement, ocean fertilization and blue carbon management (although the latter is also partly a land-based mitigation option). Ocean alkalinity enhancement has also been suggested as a solution to reduce ocean acidification which is a drop in the ocean's pH value caused by increased CO2 concentrations in the atmosphere.

The assessment of potential for ocean-based mitigation options is in 2022: "Despite limited current deployment, moderate to large future mitigation potentials are estimated for Direct Air Carbon Capture and Sequestration (DACCS), enhanced weathering (EW) and ocean-based CDR methods (including ocean alkalinity enhancement and ocean fertilization)."

Other engineering based options

Direct air capture

Main article: Direct air capture

Direct air capture is a process of capturing CO₂ directly from the ambient air (as opposed to capturing from point sources) and generating a concentrated stream of CO₂ for sequestration or utilization or production of carbon-neutral fuel and windgas. Artificial processes vary, and concerns have been expressed about the long-term effects of some of these processes.

Carbon capture and storage

Schematic showing both terrestrial and geological sequestration of carbon dioxide emissions from a large point source, for example burning natural gas

Main article: Carbon capture and storage

Carbon capture and storage (CCS) is a method to mitigate climate change by capturing carbon dioxide (CO₂) from large point sources, such as cement factories or biomass power plants, and subsequently storing it away safely instead of releasing it into the atmosphere. The IPCC estimates that the costs of halting global warming would double without CCS. Norway's Sleipner gas field, beginning in 1996, stores almost a million tons of CO₂ a year to avoid penalties in producing natural gas with unusually high levels of CO₂.

Enhanced weathering

Enhanced weathering is the removal of carbon from the air into the earth, enhancing the natural carbon cycle where carbon is mineralized into rock. The CarbFix project couples with carbon capture and storage in power plants to turn carbon dioxide into stone in a relatively short period of two years, addressing the common concern of leakage in CCS projects which stores carbon as a gas instead. While this project used basalt rocks, olivine has also shown promise.

Taking into account direct and indirect emissions, industry is the sector with the highest share of global emissions.

By sector

Buildings

See also: Electric heating

The buildings sector accounts for 23% of global energy-related CO₂ emissions About half of the energy is used for space and water heating.

A combination of electric heat pumps and building insulation can reduce the primary energy demand significantly. Generally, electrification of heating and cooling would only reduce GHG emissions if the electric power comes from low-carbon sources. A fossil-fuel power station may only deliver 3 units of electrical energy for every 10 units of fuel energy released. Electrifying heating and cooling loads may also provide a flexible resource that can participate in demand response to integrate variable renewable resources into the grid.

Heat pumps

Outside unit of an air source heat pump

A modern heat pump typically produces around two to six times more thermal energy than electrical energy consumed, giving an effective efficiency of 200 to 600%, depending on the coefficient of performance and the outside temperature. It uses an electrically driven compressor to operate a refrigeration cycle that extracts heat energy from outdoor air and moves that heat to the space to be warmed. In the summer months, the cycle can be reversed for air conditioning. In areas with average winter temperatures well below freezing, ground source heat pumps are more efficient than air-source heat pumps. The high purchase price of a heat pump compared to resistance heaters may be offset when air conditioning is also needed.

With a market share of 30% and clean electricity, heat pumps could reduce global CO₂ emissions by 8% annually. Using ground source heat pumps could reduce around 60% of the primary energy demand and 90% of CO₂ emissions of natural gas boilers in Europe in 2050 and make handling high shares of renewable energy easier. Using surplus renewable energy in heat pumps is regarded as the most effective household means to reduce global warming and fossil fuel depletion.

Cooling

See also: Passive cooling and Passive daytime radiative cooling

Refrigeration and air conditioning account for about 10% of global CO₂ emissions caused by fossil fuel-based energy production and the use of fluorinated gases. Slashing HFC consumption by 80% by midcentury could avoid more than 0.4 °C of global warming by the end of the century. About 90% of the emissions occur at the end of the equipment's life. Solutions include investing in proper disposal and refrigerants that are less polluting. Alternative cooling systems, such as passive cooling building design and installing passive daytime radiative cooling surfaces, can reduce air conditioning use. Suburbs and cities in hot and arid climates can significantly reduce energy consumption from cooling with daytime radiative cooling.

The energy consumption for cooling is expected to rise significantly due to increasing heat and availability of devices in poorer countries. Of the 2.8 billion people living in the hottest parts of the world, only 8% currently have air conditioners, compared with 90% of people in the US and Japan. By combining energy efficiency improvements with the transition away from super-polluting refrigerants, the world could avoid cumulative greenhouse gas emissions of up to 210–460 GtCO₂e over the next four decades. A shift to renewable energy in the cooling sector comes with two advantages: Solar energy production with mid-day peaks corresponds with the load required for cooling. Additionally, cooling has a large potential for load management in the electric grid.

Electric resistant heating

Radiant heaters in households are cheap and widespread but less efficient than heat pumps. In areas like Norway, Brazil, and Quebec that have abundant hydroelectricity, electric heat and hot water are common. Large scale hot water tanks can be used for demand-side management and store variable renewable energy over hours or days.

Transport

Main articles: Greenhouse gas emissions, Sustainable transport, and Green transport

Transportation emissions account for 15% of emissions worldwide. Increasing the use of public transport, low-carbon freight transport and cycling are important components of transport decarbonization.

Electric vehicles and environmentally friendly rail help to reduce the consumption of fossil fuels. In most cases, electric trains are more efficient than air transport and truck transport. Other efficiency means include improved public transport, smart mobility, carsharing and electric hybrids. Fossil-fuel powered passenger cars can be converted to electric propulsion. The production of alternative fuel without GHG emissions is only possible with high conversion losses. Furthermore, moving away from a car-dominated transport system towards low-carbon advanced public transport system is important.

Heavyweight, large personal vehicles (such as cars) require a lot of energy to move and take up much urban space. Several alternatives modes of transport are available to replace these. The European Union has made smart mobility part of its European Green Deal and in smart cities, smart mobility is also important.

Electric vehicles

See also: Phase-out of fossil fuel vehicles and Alternative fuel vehicle

Battery electric bus in Montreal

Between a quarter and three-quarters of cars on the road by 2050 are forecast to be electric vehicles. EVs use 38 megajoules per 100 km in comparison to 142 megajoules per 100 km for ICE cars. Hydrogen can be a solution for long-distance transport by trucks and hydrogen-powered ships where batteries alone are too heavy.

GHG emissions depend on the amount of green energy being used for battery or fuel cell production and charging. In a system mainly based on electricity from fossil fuels, emissions of electric vehicles can even exceed those of diesel combustion.

Shipping

Further information: Environmental effects of shipping § Greenhouse gas pollutants

In the shipping industry, the use of liquefied natural gas (LNG) as a marine bunker fuel is driven by emissions regulations. Ship operators have to switch from heavy fuel oil to more expensive oil-based fuels, implement costly flue gas treatment technologies or switch to LNG engines. Methane slip, when gas leaks unburned through the engine, lowers the advantages of LNG. Maersk, the largest container shipping line and vessel operator in the world, warns of stranded assets when investing into transitional fuels like LNG. The company lists green ammonia as one of the preferred fuel types of the future and has announced the first carbon-neutral vessel on the water by 2023, running on carbon-neutral methanol.

Hybrid and all electric ferries are suitable for short distances. Norway's goal is an all electric fleet by 2025. The E-ferry Ellen, which was developed in an EU-backed project, is in operation in Denmark.

Air travel

Further information: environmental impact of aviation

In aviation, current 180 Mt of CO₂ emissions (11% of emissions in transport) are expected to rise in most projections, at least until 2040. Aviation biofuel and hydrogen can only cover a small proportion of flights in the coming years. The market entry for hybrid-driven aircraft on regional scheduled flights is projected after 2030, for battery-powered aircraft after 2035. In October 2016, the 191 nations of the ICAO established the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), requiring operators to purchase carbon offsets to cover their emissions above 2020 levels, starting from 2021. This is voluntary until 2027.

This section is an excerpt from Environmental effects of aviation.[edit]

Aircraft engines produce gases, noise, and particulates from fossil fuel combustion, raising environmental concerns over their global effects and their effects on local air quality. Jet airliners contribute to climate change by emitting carbon dioxide (CO₂), the best understood greenhouse gas, and, with less scientific understanding, nitrogen oxides, contrails and particulates. Their radiative forcing is estimated at 1.3–1.4 that of CO₂ alone, excluding induced cirrus cloud with a very low level of scientific understanding. In 2018, global commercial operations generated 2.4% of all CO₂ emissions.

Jet airliners have become 70% more fuel efficient between 1967 and 2007, and CO₂ emissions per revenue ton-kilometer (RTK) in 2018 were 47% of those in 1990. In 2018, CO₂ emissions averaged 88 grams of CO₂ per revenue passenger per km.

While the aviation industry is more fuel efficient, overall emissions have risen as the volume of air travel has increased. By 2020, aviation emissions were 70% higher than in 2005 and they could grow by 300% by 2050.

Agriculture

See also: Greenhouse gas emissions from agriculture, Environmental impact of meat production, Insects as food, and Sustainable agriculture

As 25% of greenhouse gas emissions (GHGs) are coming from agriculture and land use, it is impossible to limit temperature rise to 1.5 degrees without addressing the emissions from agriculture. During 2021 United Nations Climate Change Conference, 45 countries pledged to give more than 4 billion dollars for transition to sustainable agriculture. The organization "Slow Food" expressed concern about the effectivity of the spendings, as they concentrate on technological solutions and reforestation en place of "a holistic agroecology that transforms food from a mass-produced commodity into part of a sustainable system that works within natural boundaries."

With 21% of the global methane emissions, cattle are a major driver on global warming. When rainforests are cut and the land is converted for grazing, the impact is even higher. This results in up to 335 kg CO_2eq emissions for the production of 1 kg beef in Brazil when using a 30-year time horizon. Other livestock, manure management and rice cultivation also produce relevant GHG emissions, in addition to fossil fuel combustion in agriculture.

Investment in improving and scaling up the production of dairy and meat alternatives leads to big greenhouse gas reductions compared with other investments. Also, photovoltaic-driven microbial protein production could use 10 times less land for an equivalent amount of protein compared to soybean cultivation.

Agricultural changes may require complementary laws and policies to drive and support dietary shifts, including changes in pet food, increases in organic food products, and substantial reductions of meat-intake (food miles usually do not play a large role).

Regenerative agriculture includes conservation tillage, diversity, rotation and cover crops, minimizing physical disturbance, minimizing the usage of chemicals. It has other benefits like improving the state of the soil and consequently yields. A research made by the Rodale institute suggests that a worldwide transition to regenerative agriculture can soak around 100% of the greenhouse gas emissions currently emitted by people. Restoring grasslands stores CO₂ with estimates that increasing the carbon content of the soils in the world's 3.5 billion hectares of agricultural grassland by 1% would offset nearly 12 years of CO₂ emissions. Allan Savory, as part of holistic management, claims that while large herds are often blamed for desertification, prehistoric lands supported large or larger herds and areas where herds were removed in the United States are still desertifying. Grazers, such as livestock that are not left to wander, would eat the grass and would minimize any grass growth. However, carbon sequestration is maximized when only part of the leaf matter is consumed by a moving herd as a corresponding amount of root matter is sloughed off too sequestering part of its carbon into the soil.

In the United States, soils account for about half of agricultural GHGs while agriculture, forestry and other land use emits 24%. The US EPA says soil management practices that can reduce the emissions of nitrous oxide (N
₂O) from soils include fertilizer usage, irrigation, and tillage.

Important mitigation options for reducing the greenhouse gas emissions from livestock include genetic selection, introduction of methanotrophic bacteria into the rumen, vaccines, feeds, toilet-training, diet modification and grazing management. Other options include just using ruminant-free alternatives instead, such as milk substitutes and meat analogues. Non-ruminant livestock (e.g. poultry) generates far fewer emissions.

A matrix of the progress in the adoption of management practices and approaches

Methods that enhance carbon sequestration in soil include no-till farming, residue mulching and crop rotation, all of which are more widely used in organic farming than in conventional farming. Because only 5% of US farmland currently uses no-till and residue mulching, there is a large potential for carbon sequestration.

Farming can deplete soil carbon and render soil incapable of supporting life. However, conservation farming can protect carbon in soils, and repair damage over time. The farming practice of cover crops has been recognized as climate-smart agriculture. Best management practices for European soils were described to increase soil organic carbon: conversion of arable land to grassland, straw incorporation, reduced tillage, straw incorporation combined with reduced tillage, ley cropping system and cover crops.

Agroforestry is one way to achieve sustainable intensification, which is farming method that can both boosts yield to supply the growing population and reduce greenhouse gas emissions. Agroforestry is the practice of integrating trees and shrubs into crop and animal farming systems, creating environmental benefits. Trees can absorb carbon dioxide from the air, leaves from the trees can enrich the soil, manure from livestock can nutrient crops and trees. Nitrogen can also be fixed by trees, which benefits crops. This method intensifies agriculture productivity while prevents deforestation, which all largely contribute to rising of CO₂.

Methane emissions in rice cultivation can be cut by implementing an improved water management, combining dry seeding and one drawdown, or a perfect execution of a sequence of wetting and drying. This results in emission reductions of up to 90% compared to full flooding and even increased yields.

Demand management and social aspects

The IPCC Sixth Assessment Report pointed out in 2022: "To enhance well-being, people demand services and not primary energy and physical resources per se. Focusing on demand for services and the different social and political roles people play broadens the participation in climate action." The report explains that behavior, lifestyle, and cultural change have a high mitigation potential in some sectors, particularly when complementing technological and structural change.

Aspects to consider include:

• Potential of demand-side actions and service provisioning systems (for example: "Rapid and deep changes in demand make it easier for every sector to reduce GHG emissions in the short and medium term.")
• Social aspects of demand-side mitigation actions
• Preconditions and instruments to enable demand-side transformation (for example: Social equity plays a key motivating role for mitigating climate change)

It has been estimated that only 0.12% of all funding for climate-related research is spent on the social science of climate change mitigation. Vastly more funding is spent on natural science studies of climate change and considerable sums are also spent on studies of impact of and adaptation to climate change.

Lifestyle and behavior

The emissions of the richest 1% of the global population account for more than twice the combined share of the poorest 50%.

This section is an excerpt from Individual action on climate change.[edit]

Individual action on climate change can include personal choices with regards to diet, travel, lifestyle, consumption of goods and services, family size and so on. Individuals can also get active in local and political advocacy work around climate action. People who wish to reduce their carbon footprint (particularly those in high income countries with high consumption lifestyles), can for example reduce air travel and driving cars, they can eat mainly a plant-based diet, use consumer products for longer, or have fewer children. Avoiding meat and dairy foods has been called "the single biggest way" how an individual can reduce their environmental impact. Scholars find that excessive consumption is more to blame for climate change than population increase. High consumption lifestyles have a greater environmental impact, with the richest 10% of people emitting about half the total lifestyle emissions.

Some commentators say that actions taken by individual consumers, such as adopting a sustainable lifestyle, are insignificant compared to actions on the political level. Others say that individual action does lead to collective action because "lifestyle change can build momentum for systemic change."

Personal carbon trading

Since 1950, world population has tripled.

Some forms of personal carbon trading (carbon rationing) could be an effective component of climate change mitigation, with the economic recovery of COVID-19 and new technical capacity having opened a favorable window of opportunity for initial test runs of such in appropriate regions, while many questions remain largely unaddressed. However, carbon rationing could have a larger effect on poorer households as "people in the low-income groups may have an above-average energy use, because they live in inefficient homes".

Dietary change

Main article: Low-carbon diet

The widespread adoption of a vegetarian diet could cut food-related greenhouse gas emissions by 63% by 2050. Addressing the high methane emissions by cattle, a 2016 study analyzed surcharges of 40% on beef and 20% on milk and suggests that an optimum plan would reduce emissions by 1 billion tonnes per year. China introduced new dietary guidelines in 2016 which aim to cut meat consumption by 50% and thereby reduce greenhouse gas emissions by 1 billion tonnes by 2030. Overall, food accounts for the largest share of consumption-based GHG emissions with nearly 20% of the global carbon footprint. Almost 15% of all anthropogenic GHG emissions has been attributed to the livestock sector alone.

A shift towards plant-based diets would help to mitigate climate change. In particular, reducing meat consumption would help to reduce methane emissions. If high-income nations switched to a plant-based diet, vast amounts of land used for animal agriculture could be allowed to return to their natural state, which in turn has the potential to sequester 100 billion tons of CO₂ by the end of the century.

Urban systems and other settlements

Main article: Urban planning

Further information: Smart mobility and Carfree city

Co-benefits of climate change mitigation;
active lifestyle, benefits to wildlife and the natural environment, economic development and employment, air quality, energy access, urban resilience and decarbonisation

Bicycles have almost no carbon footprint compared to cars, and canal transport may represent a positive option for certain types of freight in the 21st century.

Effective urban planning to reduce sprawl aims to decrease the distance travelled by vehicles, lowering emissions from transportation. Personal cars are extremely inefficient at moving passengers, while public transport and bicycles are many times more efficient (as is the simplest form of human transportation, walking). All of these are encouraged by urban/community planning and are an effective way to reduce greenhouse gas emissions. Inefficient land use development practices have increased infrastructure costs as well as the amount of energy needed for transportation, community services, and buildings. Switching from cars by improving walkability and cycling infrastructure is either free or beneficial to a country's economy as a whole.

"Urban mitigation options can be categorized into three broad strategies: (1) reducing urban energy 3 consumption across all sectors, including through spatial planning and infrastructure; (2) electrification 4 and switching to net zero emissions resources; and (3) enhancing carbon stocks and uptake through 5 urban green and blue infrastructure, which can also offer multiple co-benefits."

Cities have big potential for reducing greenhouse gas emissions. They emitted 28 GtCO2-eq in the year 2020. Without any action cities supposed to emit 65 GtCO2-eq by the year 2050. With full scale mitigation action the emissions will be near zero, in the worst case they will be only 3 GtCO2-eq. City planning, supporting mixed use of space, transit, walking, cycling, sharing vehicles can reduce urban emissions by 23% – 26%. Urban forests, lakes and other blue and green infrastructure can reduce emissions directly and indirectly (trough reduce in energy demand for cooling for example).

At the same time, a growing number of citizens and government officials have begun advocating a smarter approach to land use planning. These smart growth practices include compact community development, multiple transportation choices, mixed land uses, and practices to conserve green space. These programs offer environmental, economic, and quality-of-life benefits; and they also serve to reduce energy usage and greenhouse gas emissions.

Reducing the number of cars on the road, for example through proof-of-parking requirements, corporate car sharing, road reallocation (from only car use to cycling road, ...), circulation plans, bans on on-street parking or by increasing the costs of car ownership can help in reducing traffic congestion in cities.

Approaches such as New Urbanism and transit-oriented development seek to reduce distances travelled, especially by private vehicles, encourage public transit and make walking and cycling more attractive options. This is achieved through "medium-density", mixed-use planning and the concentration of housing within walking distance of town centers and transport nodes.

Smarter growth land use policies have both a direct and indirect effect on energy consuming behavior. For example, transportation energy usage, the number one user of petroleum fuels, could be significantly reduced through more compact and mixed use land development patterns (urban agriculture, urban trees), which in turn could be served by a greater variety of non-automotive based transportation choices.

Changes in urban form, behavior programs, the circular economy, the shared economy, and digitalization trends can support systemic changes that lead to reductions in demand for transport services or expands the use of more efficient transport modes. Cities can reduce their transport-related fuel consumption by around 25% through combinations of more compact land use and the provision of less car-dependent transport infrastructure. Appropriate infrastructure, including protected pedestrian and bike pathways, can also support much greater localized active travel. Transport demand management incentives are expected to be necessary to support these systemic changes. There is mixed evidence of the effect of circular economy initiatives, shared economy initiatives, and digitalization on demand for transport services. For example, while dematerialization can reduce the amount of material that need to be transported to manufacturing facilities, an increase in online shopping with priority delivery can increase demand for freight transport. Similarly, while teleworking could reduce travel demand, increased ridesharing could increase vehicle-km travelled.

Building design

Main articles: Sustainable architecture and Green building

According to the IPCC Sixth Assessment Report buildings emitted 21% of global GHG emissions in the year 2019. The report introduces a new scheme for reducing GHG emissions in buildings: SER = Sufficiency, Efficiency, Renewable. Sufficiency measures do not need very complex technology, energy supply, maintenance or replacement during the life of the building. Those include, natural ventilation, green roofs, white walls, mixed use of spaces, collective use of devices etc. There are multiple links between emissions from buildings and emissions from other sectors. Reducing GHG emissions from buildings is linked to Sharing economy and Circular economy.

With strong action to reduce energy consumption of buildings "average energy intensity of the global building stock would decrease by more than 80% by 2050."

New buildings can be constructed using passive solar building design, low-energy building, or zero-energy building techniques, using renewable heat sources. Existing buildings can be made more efficient through the use of insulation, high-efficiency appliances (particularly hot water heaters and furnaces), double- or triple-glazed gas-filled windows, external window shades, and building orientation and siting. Renewable heat sources such as shallow geothermal and passive solar energy reduce the amount of greenhouse gasses emitted. In addition to designing buildings which are more energy-efficient to heat, it is possible to design buildings that are more energy-efficient to cool by using lighter-coloured, more reflective materials in the development of urban areas (e.g. by painting roofs white) and planting trees. This saves energy because it cools buildings and reduces the urban heat island effect thus reducing the use of air conditioning.

Population growth

Further information: Individual action on climate change § Family size

Population growth results in higher greenhouse gas emissions in most regions, particularly Africa. However, economic growth has a bigger effect than population growth. It is the rising incomes, changes in consumption and dietary patterns, together with population growth, which causes pressure on land and other natural resources, and leads to more greenhouse gas emissions and less carbon sinks. Scholars have pointed out that "In concert with policies that end fossil fuel use and incentivize sustainable consumption, humane policies that slow population growth should be part of a multifaceted climate response." It is known that "advances in female education and reproductive health, especially voluntary family planning, can contribute greatly to reducing world population growth".

Investment and finance

Investment

Main article: Business action on climate change

The European Investment Bank's Investment Survey also found that Western and Northern European firms are more likely to invest in climate mitigation.

More firms plan to invest in climate change mitigation, specifically focusing on low-carbon sectors.

The European Investment Bank's Investment Survey 2020 found that firms with active climate policies invest more in energy efficiency.

More than 1000 organizations with a worth of US$8 trillion have made commitments to fossil fuel divestment. Socially responsible investing funds allow investors to invest in funds that meet high environmental, social and corporate governance (ESG) standards. Proxy firms can be used to draft guidelines for investment managers that take these concerns into account.

As well as a policy risk, Ernst and Young identify physical, secondary, liability, transitional and reputation-based risks. Therefore, it is increasingly seen to be in the interest of investors to accept climate change as a real threat which they must proactively and independently address.

The European Investment Bank's investment survey 2021 found that during the COVID-19 pandemic, climate change was addressed by 43% of EU enterprises. Despite the pandemic's effect on businesses, the percentage of firms planning climate-related investment rose to 47%. This was a rise from 2020, when the percentage of climate related investment was at 41%.

In 2021, firms' investments in climate change mitigation were being hampered by uncertainty about the regulatory environment and taxation.

As of 2021, one current approach under development is binary "labelling" of investments as "green" according to an EU governmental body-created "taxonomy" for voluntarily financial investment redirection based on this categorization.

Funding

Main article: Climate finance

Funding, such as the Green Climate Fund, is often provided by nations, groups of nations and increasingly NGO and private sources. These funds are often channelled through the Global Environmental Facility (GEF). This is an environmental funding mechanism in the World Bank which is designed to deal with global environmental issues. The GEF was originally designed to tackle four main areas: biological diversity, climate change, international waters and ozone layer depletion, to which land degradation and persistent organic pollutant were added. The GEF funds projects that are agreed to achieve global environmental benefits that are endorsed by governments and screened by one of the GEF's implementing agencies.

Economics

Main article: Economics of climate change mitigation

See also: Green industrial policy

There is a debate about a potentially critical need for new ways of economic accounting, including directly monitoring and quantifying positive real-world environmental effects such as air quality improvements and related unprofitable work like forest protection, alongside far-reaching structural changes of lifestyles as well as acknowledging and moving beyond the limits of current economics such as GDP. Some argue that for effective climate change mitigation degrowth has to occur, while some argue that eco-economic decoupling could limit climate change enough while continuing high rates of traditional GDP growth. There is also research and debate about requirements of how economic systems could be transformed for sustainability – such as how their jobs could transition harmonously into green jobs – a just transition – and how relevant sectors of the economy – like the renewable energy industry and the bioeconomy – could be adequately supported.

While degrowth is often believed to be associated with decreased living standards and austerity measures, many of

Physical risks of climate change top the list of business concerns for US and EU firms.

its proponents seek to expand universal public goods (such as public transport), increase health (fitness, wellbeing and freedom from diseases) and increase various forms of, often unconventional commons-oriented, labor.

Investments to tackle climate change

To this end, the application of both advanced technologies and reductions in various demands, including via overall reduced labor time or sufficiency-oriented strategies, are considered to be important by some.

On the level of international trade, domestic trade, production and product designs, policies such as for "digital product passports" have been proposed to link products with environment-related information which could be a requirement for both further measures as well as unfacilitated bottom-up consumer- and business-adaptations.

Companies, investors and politicians

Sometimes, top contributors to greenhouse gas emissions are identified as the companies emitting most GHGs. Similarly, investing asset management firms are often identified as controllers of large amounts of contemporary financial value with insufficient dedication to climate change targets, with the largest four asset managers controlling around 20% of the world's listed market values – an aggregate assets under management of $20 trillion as of 2021.

However, it may not necessarily be the structural interest of these companies to help mitigate climate change sufficiently instead of striving to generate near-maximum profit in the contemporary socioeconomic system, a globalized competitive consumption-demanding environment, and use all legal means to delay climate change action if such is beneficial (see below) – their products are being bought by consumers (for various reasons), the stock market likely underestimates (or cannot value) e.g. social benefits of climate mitigation, they are regulatable by governments, and don't have as much power as many large states (or groups of such) which e.g. have capacities of law enforcement and military, customs, legal frameworks and for business-, media-, education-, global-, trade- and industrial policies. A fraction of such policies or measures are invariably initially at least partly unpopular, and in the contemporary decision-making environment of (campaign-marketing-, party-, media-, and electoral/referendum plain votes-based) politics, unpopular decisions may be difficult for politicians to enact directly or help facilitate indirectly. The question of the largest responsibility or driver may be about who is holding (or withholding) the power (and capacity) to create and change the systems that cause climate change, such as the transportation system. While it has been pointed out that blaming drivers may not be constructive in terms of climate change mitigation, understanding these links of the supply chain may allow better understanding of the complex system or untangling the structures of power and decision-making that inhibit climate action.

Costs

Globally, the benefits of keeping warming under 2 °C exceed the costs. However, some consider cost–benefit analysis unsuitable for analysing climate change mitigation as a whole but still useful for analysing the difference between a 1.5 °C target and 2 °C. The OECD has been applying economic models and qualitative assessments to inform on climate change benefits and tradeoffs.One way of estimating the cost of reducing emissions is by considering the likely costs of potential technological and output changes. Policy makers can compare the marginal abatement costs of different methods to assess the cost and amount of possible abatement over time. The marginal abatement costs of the various measures will differ by country, by sector, and over time. Mitigation costs will vary according to how and when emissions are cut: early, well-planned action will minimise the costs.

Many economists estimate the cost of climate change mitigation at between 1% and 2% of GDP. In 2019, scientists from Australia and Germany presented the "One Earth Climate Model" showing how temperature increase can be limited to 1.5 °C for 1.7 trillion dollars a year. According to this study, a global investment of approximately $1.7 trillion per year would be needed to keep global warming below 1.5°C. The method used by the One Earth Climate Model does not resort to dangerous geo-engineering methods. Whereas this is a large sum, it is still far less than the subsidies governments currently provided to the ailing fossil fuel industry, estimated at more than $5 trillion per year by the International Monetary Fund. Abolishing fossil fuel subsidies is very important but must be done carefully to avoid making poor people poorer. Ian Parry, lead author of the 2021 IMF report "Still Not Getting Energy Prices Right: A Global and Country Update of Fossil Fuel Subsidies", said: "Some countries are reluctant to raise energy prices because they think it will harm the poor. But holding down fossil fuel prices is a highly inefficient way to help the poor, because most of the benefits accrue to wealthier households. It would be better to target resources towards helping poor and vulnerable people directly."

Benefits

By limiting climate change, some of the costs of the effects of climate change can be avoided.

According to the Stern Review, inaction can be as high as the equivalent of losing at least 5% of global gross domestic product (GDP) each year, now and forever (up to 20% of the GDP or more when including a wider range of risks and impacts), whereas mitigating climate change will only cost about 2% of the GDP. Also, delaying to take significant reductions in greenhouse gas emissions may not be a good idea, when seen from a financial perspective. Mitigation solutions are often evaluated in terms of costs and greenhouse gas reduction potentials, missing out on the consideration of direct effects on human well-being.

Mitigation measures may have many health co-benefits – potential measures can not only mitigate future health impacts from climate change but also improve health directly.

Climate change mitigation is also an issue of intergenerational justice with nonintervention thought by some to violate future people's freedom – conversely, mitigation may preserve societal freedoms and range of viable basic choices.

The research organization Project Drawdown identified global climate solutions and ranked them according to their benefits. Early deaths due to fossil fuel air pollution with a temperature rise to 2 °C cost more globally than mitigation would: and in India cost 4 to 5 times more. Air quality improvement is a near-term benefit among the many societal benefits from climate change mitigation, including substantial health benefits. Studies suggest that demand-side climate change mitigation solutions have largely beneficial effects on 18 constituents of well-being.

Sharing

One of the aspects of mitigation is how to share the costs and benefits of mitigation policies. Rich people tend to emit more GHG than poor people. Activities of the poor that involve emissions of GHGs are often associated with basic needs, such as cooking. For richer people, emissions tend to be associated with things such as eating beef, cars, frequent flying, and home heating. The impacts of cutting emissions could therefore have different impacts on human welfare according to wealth.

Distributing emissions abatement costs

There have been different proposals on how to allocate responsibility for cutting emissions (Banuri et al., 1996, pp. 103–105):

• Egalitarianism: this system interprets the problem as one where each person has equal rights to a global resource, i.e., polluting the atmosphere.
• Basic needs: this system would have emissions allocated according to basic needs, as defined according to a minimum level of consumption. Consumption above basic needs would require countries to buy more emission rights. From this viewpoint, developing countries would need to be at least as well off under an emissions control regime as they would be outside the regime.
• Proportionality and polluter-pays principle: Proportionality reflects the ancient Aristotelian principle that people should receive in proportion to what they put in, and pay in proportion to the damages they cause. This has a potential relationship with the "polluter-pays principle", which can be interpreted in a number of ways:
  • Historical responsibilities: this asserts that allocation of emission rights should be based on patterns of past emissions. Two-thirds of the stock of GHGs in the atmosphere at present is due to the past actions of developed countries (Goldemberg et al., 1996, p. 29).
  • Comparable burdens and ability to pay: with this approach, countries would reduce emissions based on comparable burdens and their ability to take on the costs of reduction. Ways to assess burdens include monetary costs per head of population, as well as other, more complex measures, like the UNDP's Human Development Index.
  • Willingness to pay: with this approach, countries take on emission reductions based on their ability to pay along with how much they benefitfrom reducing their emissions.

Specific proposals

• Equal per capita entitlements: this is the most widely cited method of distributing abatement costs, and is derived from egalitarianism (Banuri et al., 1996, pp. 106–107). This approach can be divided into two categories. In the first category, emissions are allocated according to national population. In the second category, emissions are allocated in a way that attempts to account for historical (cumulative) emissions.
• Status quo: with this approach, historical emissions are ignored, and current emission levels are taken as a status quo right to emit (Banuri et al., 1996, p. 107). An analogy for this approach can be made with fisheries, which is a common, limited resource. The analogy would be with the atmosphere, which can be viewed as an exhaustible natural resource (Goldemberg et al., 1996, p. 27). In international law, one state recognized the long-established use of another state's use of the fisheries resource. It was also recognized by the state that part of the other state's economy was dependent on that resource.

Barriers to implementation

See also: Climate justice § Debate on complications

A typology of discourses aimed at delaying climate change mitigation

It has been suggested that the main barriers to implementation are uncertainty, institutional void, short time horizon of policies and politicians and missing motives and willingness to start adapting as well as the negative impacts of COVID-19 pandemic When information on climate change is held between the large numbers of actors involved it can be highly dispersed, context specific or difficult to access causing fragmentation to be a barrier. The short time horizon of policies and politicians often means that climate change policies are not implemented in favour of socially favoured societal issues. Statements are often posed to keep the illusion of political action to prevent or postpone decisions being made. There may be cause for concern about metal requirement for relevant technologies such as photovoltaics. Many developing nations have made national adaptation programs which are frameworks to prioritize adaption needs.

Carbon budgets by country

An international policy to allocate carbon budgets to individual countries has not been implemented. This question raises fairness issues. With a linear reduction starting from the status quo, industrial countries would have a greater share of the remaining global budget. Using an equal share per capita globally, emission cuts in industrial countries would have to be extremely sharp.

Geopoliticial impacts

Further information: Renewable energy § Geopolitics of renewable energy

In 2019, oil and gas companies were listed by Forbes with sales of US$4.8 trillion, about 5% of the global GDP. Net importers such as China and the EU would gain advantages from a transition to low-carbon technologies driven by technological development, energy efficiency or climate change policy, while Russia, the USA or Canada could see their fossil fuel industries nearly shut down. On the other hand, countries with large areas such as Australia, Russia, China, the US, Canada and Brazil and also Africa and the Middle East have a potential for huge installations of renewable energy. The production of renewable energy technologies requires rare-earth elements with new supply chains.

Economic interests of fossil fuel companies

Potential CO₂ emissions from large fossil fuel projects 'carbon bombs' per country

Distribution of committed CO₂ emissions from developed fossil fuel reserves

For a 50% probability of limiting global warming by 2050 to 1.5 °C large amounts of fossil fuels would need to be left underground. In various nations oil and gas companies such as Qatar Energy, Gazprom and Saudi Aramco are planning new large fossil fuel projects, called "carbon bombs", that would defeat the 1.5 °C climate goal if not "defused" and produce greenhouse gases equivalent to a decade of CO₂ emissions from China. Researchers have identified the 425 biggest fossil fuel extraction projects globally, of which 40% as of 2020 are new projects that haven't yet started extraction. As of 2022, countries like China and India are planning to boost production of coal and other fossil fuels.

According to a study, "staying within a 1.5 °C carbon budget (50% probability) implies leaving almost 40% of 'developed reserves' of fossil fuels unextracted". Climate policies-induced future lost financial profits from global stranded fossil-fuel assets would lead to major losses for freely managed wealth of investors in advanced economies in current economics.

Regional differences

Regional barriers to mitigation include:

• Developing countries:
  • In many developing countries, importing mitigation technologies might lead to an increase in their external debt and balance-of-payments deficit.
  • Technology transfer to these countries can be hindered by the possibility of non-enforcement of intellectual property rights. This leaves little incentive for private firms to participate. On the other hand, enforcement of property rights can lead to developing countries facing high costs associated with patents and licensing fees.
  • A lack of available capital and finance is common in developing countries.. Together with the absence of regulatory standards, this barrier supports the proliferation of inefficient equipment.
• Economies in transition: In the New Independent States, a lack of liquidity and a weak environmental policy framework are barriers to investment in mitigation.

Government policies and action

Main article: Politics of climate change

See also: Climate change § Policies and politics, and Climate change mitigation framework

Climate Action Tracker described the situation on 9 November 2021 as follows: the global temperature will rise by 2.7 °C by the end of the century with current policies and by 2.9 °C with nationally adopted policies. The temperature will rise by 2.4 °C if only the pledges for 2030 are implemented, by 2.1 °C if the long-term targets are also achieved. If all the announced targets are fully achieved the rise in global temperature will peak at 1.9 °C and go down to 1.8 °C by the year 2100. All the information about all climate pledges is sent to the Global Climate Action Portal - Nazca. The scientific community is checking their fulfillment.

Studies have explored how countries could transform for decarbonization.

Paris Agreement

Main article: Paris Agreement

The Paris Agreement has become the main current international agreement on combating climate change. Each country must determine, plan, and regularly report on the contribution that it undertakes to mitigate global warming. Climate change mitigation measures can be written down in national environmental policy documents like the nationally determined contributions (NDC). The Paris agreement succeeds the 1997 Kyoto Protocol which expired in 2020. Countries that ratified the Kyoto protocol committed to reduce their emissions of carbon dioxide and five other greenhouse gases, or engage in emissions trading if they maintain or increase emissions of these gases.

In 2015, two official UNFCCC scientific expert bodies came to the conclusion that, "in some regions and vulnerable ecosystems, high risks are projected even for warming above 1.5 °C". This expert position was, together with the strong diplomatic voice of the poorest countries and the island nations in the Pacific, the driving force leading to the decision of the Paris Conference 2015, to lay down this 1.5 °C long-term target on top of the existing 2 °C goal.

How well each individual country is on track to achieving its Paris agreement commitments can be followed on-line. The negative impact of COVID-19 pandemic has placed a challenge to achieve the Paris Agreement, with less significant support from the respondents from less developed countries.

Additional commitments

In addition to the main agreements, there are many additional pledges made by international coalitions, countries, cities, regions and businesses. According to a report published in September 2019 before the 2019 UN Climate Action Summit, full implementation of all pledges, including those in the Paris Agreement, will be sufficient to limit temperature rise to 2 degrees but not to 1.5 degrees. After the report was published, additional pledges were made in the September climate summit and in December of that year.

In December 2020 another climate action summit was held and important commitments were made. The organizers stated that, including the commitments expected in the beginning of the following year, countries representing 70% of the global economy will be committed to reach zero emissions by 2050.

In September 2021 the US and EU launched the Global Methane Pledge to cut methane emissions by 30% by 2030. UK, Argentina, Indonesia, Italy and Mexico joined the initiative, "while Ghana and Iraq signaled interest in joining, according to a White House summary of the meeting, which noted those countries represent six of the top 15 methane emitters globally". Israel also joined the initiative

Some information about the pledges is collected and analyzed in the Global Climate Action portal, which enables the scientific community to check their fulfilment.

Montreal protocol

Although not designed for this purpose, the Montreal Protocol has benefited climate change mitigation efforts. The Montreal Protocol is an international treaty that has successfully reduced emissions of ozone-depleting substances (for example, CFCs), which are also greenhouse gases.

Carbon pricing

Main article: Carbon price

Carbon emission trade – allowance prices from 2008

Additional costs on GHG emissions can lower competitiveness of fossil fuels and accelerate investments into low-carbon sources of energy. A growing number of countries raise a fixed carbon tax or participate in dynamic carbon emission trading (ETS) systems. In 2021, more than 21% of global GHG emissions were covered by a carbon price, a major increase due to the introduction of the Chinese national carbon trading scheme.

Trading schemes offer the possibility to limit emission allowances to certain reduction targets. However, an oversupply of allowances keeps most ETS at low price levels around $10 with a low impact. This includes the Chinese ETS which started with $7/tCO₂ in 2021. One exception is the European Union Emission Trading Scheme where prices began to rise in 2018, exceeding €63/tCO₂ (75 $) in 2021. This results in additional costs of about €0.04/KWh for coal and €0.02/KWh for gas combustion for electricity, depending on the emission intensity.

Latest models of the social cost of carbon calculate a damage of more than $3000 per ton CO₂ as a result of economy feedbacks and falling global GDP growth rates, while policy recommendations for a carbon price range from about $50 to $200.

Most energy taxes are still levied on energy products and motor vehicles, rather than on CO₂ emissions directly. Non-transport sectors as the agricultural sector, which produces large amounts of methane, are typically left untaxed by current policies.

The revenue of carbon pricing can used to support policies that promote carbon neutrality. Another approach the concept of a carbon fee and dividend which includes the redistribution on a per-capita basis. As a result, households with a low consumption can even benefit from carbon pricing.

Policies by country

See also: Climate change and cities and Climate change scenario § National climate (change) projections

Many countries are aiming for net zero emissions, and many have either carbon taxes or carbon emission trading. As of the year 2021, three countries became carbon negative, meaning they remove from the atmosphere more Greenhouse gas emissions then they emit. The countries are: Bhutan, Suriname, Panama. The countries formed a small coalition at 2021 United Nations Climate Change Conference and asked for help so that other countries will join it.

Climate change mitigation policies can have a large and complex impact, both positive and negative, on the socio-economic status of individuals and countries. Without “well-designed and inclusive policies, climate change mitigation measures can place a higher financial burden on poor households.”

Emission trading and carbon taxes around the world (2019)

  Carbon emission trading implemented or scheduled

  Carbon tax implemented or scheduled

  Carbon emission trading or carbon tax under consideration

United States

Main article: Greenhouse gas emissions by the United States

Efforts to reduce greenhouse gas emissions by the United States include energy policies which encourage efficiency through programs like Energy Star, Commercial Building Integration, and the Industrial Technologies Program.

In the absence of substantial federal action, state governments have adopted emissions-control laws such as the Regional Greenhouse Gas Initiative in the Northeast and the Global Warming Solutions Act of 2006 in California. In 2019 a new climate change bill was introduced in Minnesota. One of the targets, is making all the energy of the state carbon free, by 2030.

China

Main article: Greenhouse gas emissions by China

In 2020, China committed to peak emissions by 2030 and reach net zero by 2060; following the 2021 blackouts, officials indicated the 2030 target was something "to strive to" and not necessarily to be met. In order to limit warming to 1.5 °C coal plants in China without carbon capture must be phased out by 2045. The Chinese national carbon trading scheme started in 2021.

With more than 12 GtCO₂, China is the largest GHG emitter worldwide, still investing into new coal plants. On the other hand, China is also installing the largest capacities of renewable energy worldwide. In recent years, Chinese companies have flooded the world market with high-performance photovoltaic modules, resulting in competitive prices. China is also building a HVDC grid.

Chinas export-embodied emissions are estimated at a level of 1.7 GtCO₂ per year.

European Union

Further information: Climate change in Europe, European Commissioner for the Environment, European Climate Change Programme, and European Green Deal

The climate commitments of the European Union are divided into three main categories: targets for the year 2020, 2030 and 2050. The European Union claim that their policies are in line with the goal of the Paris Agreement.

• Targets for 2020: Reduce GHG emissions by 20% from the level in 1990, produce 20% of energy from renewable sources, increase Energy Efficiency by 20%.
• Targets for 2030: Reduce GHG emission by 40% from the level of 1990. In 2019 The European Parliament adopted a resolution upgrading the target to 55%, produce 32% of energy from renewables, increase energy efficiency by 32.5%.
• Targets for 2050: become climate neutral.

The European Union claims that they have already achieved the 2020 target for emission reduction and have the legislation needed to achieve the 2030 targets. Already in 2018, its GHG emissions were 23% lower that in 1990.

Low and middle income countries

In order to reconcile economic development with mitigating carbon emissions, developing countries need particular support, both financial and technical. One of the means of achieving this is the Kyoto Protocol's Clean Development Mechanism (CDM). The World Bank's Prototype Carbon Fund is a public private partnership that operates within the CDM.

An important point of contention, however, is how overseas development assistance not directly related to climate change mitigation is affected by funds provided to climate change mitigation. One of the outcomes of the UNFCC Copenhagen Climate Conference was the Copenhagen Accord, in which developed countries promised to provide US$30 million between 2010 and 2012 of new and additional resources. Yet it remains unclear what exactly the definition of additional is and the European Commission has requested its member states to define what they understand to be additional, and researchers at the Overseas Development Institute have found four main understandings:

1. Climate finance classified as aid, but additional to (over and above) the '0.7%' ODA target;
2. Increase on previous year's Official Development Assistance (ODA) spent on climate change mitigation;
3. Rising ODA levels that include climate change finance but where it is limited to a specified percentage; and
4. Increase in climate finance not connected to ODA.

The main point being that there is a conflict between the OECD states budget deficit cuts, the need to help developing countries adapt to develop sustainably and the need to ensure that funding does not come from cutting aid to other important Millennium Development Goals.

However, none of these initiatives suggest a quantitative cap on the emissions from developing countries. This is considered as a particularly difficult policy proposal as the economic growth of developing countries are proportionally reflected in the growth of greenhouse emissions.

In an attempt to provide more opportunities for developing countries to adapt clean technologies, UNEP and WTO urged the international community to reduce trade barriers and to conclude the Doha trade round "which includes opening trade in environmental goods and services".

In 2019 week of climate action in Latin America and the Caribbean result in a declaration in which leaders says that they will act to reduce emissions in the sectors of transportation, energy, urbanism, industry, forest conservation and land use and "sent a message of solidarity with all the people of Brazil suffering the consequences of the rainforest fires in the Amazon region, underscoring that protecting the world's forests is a collective responsibility, that forests are vital for life and that they are a critical part of the solution to climate change".

Monitoring

Satellites are increasingly being used for locating and measuring greenhouse gas emissions and deforestation. Earlier, scientists largely relied on or calculated estimates of greenhouse gas emissions and governments' self-reported data. They can also evaluate the environmental impact of policies and events such as the impact of the COVID-19 pandemic on the environment. Various other technologies are also being used for environmental monitoring.

It has been proposed that if politicians and business leaders know their actions (or inaction) are being recorded for future use, this could have immediate impacts.

While the status of most goals set for 2020 have not been evaluated in a definitive and detailed way or reported on by the media, the world failed to meet most or all international goals set for that year.

As the 2021 United Nations Climate Change Conference occurred in Glasgow, the group of researchers running the Climate Action Tracker reported that of countries responsible for 85% of GHG emissions, only four polities (responsible for 6% of global GHG emissions) – EU, UK, Chile and Costa Rica – have published a detailed official policy‑plan that describes the steps and ways by which 2030 mitigation targets could be realized. There are organizations that aim to transparently, neutrally and credibly monitor progress of climate change mitigation such as of pledges, goals, initiatives and other developments.

See also

• Climate movement
• Climate change denial

Sources

IPCC reports

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IRENA

By the International Renewable Energy Agency

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