Climate change adaptation

Adapting to climate change involves structural, physical, social and institutional approaches. Clockwise from top left: reforestation and other habitat conservation; seawalls to protect against storm surge worsened by sea level rise; green roofs to moderate urban heat islands; selective breeding for drought-resistant crops.

Climate change adaptation is the process of adjusting to current or expected effects of climate change. For humans, adaptation aims to moderate or avoid harm, and exploit opportunities; for natural systems, humans may intervene to help adjustment. Adaptation actions can be either incremental (actions where the central aim is to maintain the essence and integrity of a system) or transformative (actions that change the fundamental attributes of a system in response to climate change and its impacts). The need for adaptation varies from place to place, depending on the risk to human or ecological systems.

Adaptation actions can be grouped into three categories: Structural and physical adaptation (this can be grouped into engineering and built environment, technological, ecosystem-based, services); Social adaptation (educational, informational, behavioral); and Institutional adaptation (economic organizations, laws and regulation, government policies and programs).

Adaptation is especially important in developing countries since those countries are most vulnerable to climate change and are bearing the brunt of the effects of climate change. Human adaptive capacity is unevenly distributed across different regions and populations, and developing countries generally have less capacity to adapt. Adaptive capacity is closely linked to social and economic development.

In general higher levels of development mean higher adaptive capacity, but some development locks people in to certain patterns or behaviors. And the most developed areas may have low adaptation capacity to new types of natural hazards, not previously experienced, relative to more familiar natural hazards. The economic costs of adaptation to climate change are likely to cost billions of dollars annually for the next several decades.

Definition

Climate change adaptation is defined as:

• "In human systems, as the process of adjustment to actual or expected climate and its effects in order to moderate harm or take advantage of beneficial opportunities."
• "In natural systems, adaptation is the process of adjustment to actual climate and its effects; human intervention may facilitate this."

Related activities

Disaster risks, response and preparedness

Further information: Disaster response § Disaster response technologies, and Disaster risk reduction

Because climate change is one contributor to disaster risk, climate change adaptation is sometimes seen as one of many processes within disaster risk reduction. In turn, disaster risk reduction should sit within sustainable development to avoid isolation from topics wider than disaster risk.

Disasters are often triggered by natural hazards but are always linked to human action (or inaction) or rooted in anthropogenic processes. Disasters, economic loss and the underlying vulnerabilities that drive risk are increasing, and global risks like climate change are having major impacts in every locality. As climate change is projected to increase the frequency and severity of extreme weather events and disasters, adaptation may also include measures towards increased preparedness and relevant disaster response capacities.

Climate change mitigation

Further information: Climate change mitigation and Effects of climate change on human health § Health co-benefits from mitigation and adaptation

Many expert bodies agree that while climate change mitigation is important, adaptation to the effects of global warming will still be necessary. These expert bodies include for example the IPCC Working Group II ("Impacts, Adaptation and Vulnerability,") the United States National Academy of Sciences, the United Nations Disaster Risk Reduction Office, and other science policy experts.

There are some synergies and trade-offs between adaptation and mitigation. Adaptation measures often offer short-term benefits, whereas mitigation has longer-term benefits. Sometimes climate-relevant actions may point in different directions. For instance, compact urban development may lead to reduced transport and building greenhouse gas emissions. On the other hand, it may increase the urban heat island effect, leading to higher temperatures and increasing exposure, making adaptation more challenging.

Synergies include the benefits of public transport for both mitigation and adaptation. Public transport has lower greenhouse gas emissions per kilometer travelled than cars. A good public transport network also increases resilience in case of disasters: evacuation and emergency access becomes easier. Reduced air pollution from public transport improves health, which in turn may lead to improved economic resilience, as healthy workers perform better.

Purposes

Diagram explaining the relationships between risk, hazard mitigation, resilience, and adaptation

Respond to effects of climate change

Main article: Effects of climate change

The Paris Agreement of 2015 requires countries to keep global temperature rise this century to less than 2 °C above pre-industrial levels, and to pursue efforts to limit the temperature increase to 1.5 °C. Even if greenhouse gas emissions are stopped relatively soon, global warming and its effects will last many years due to the inertia of the climate system, so both carbon neutrality ("net zero") and adaptation are necessary.

The current level of warming is 1.2 °C (2.2 °F) as of 2022, and is on track to increase to 2.5 to 2.9 °C (4.5 to 5.2 °F) by the end of the century. This is causing a variety of secondary effects.

This section is an excerpt from Effects of climate change.[edit]

Effects of climate change are well documented and growing for Earth's natural environment and human societies. Changes to the climate system include an overall warming trend, changes to precipitation patterns, and more extreme weather. As the climate changes it impacts the natural environment with effects such as more intense forest fires, thawing permafrost, and desertification. These changes impact ecosystems and societies, and can become irreversible once tipping points are crossed. Climate activists are engaged in a range of activities around the world that seek to ameliorate these issues or prevent them from happening.

The effects of climate change vary in timing and location. Up until now the Arctic has warmed faster than most other regions due to climate change feedbacks. Surface air temperatures over land have also increased at about twice the rate they do over the ocean, causing intense heat waves. These temperatures would stabilize if greenhouse gas emissions were brought under control. Ice sheets and oceans absorb the vast majority of excess heat in the atmosphere, delaying effects there but causing them to accelerate and then continue after surface temperatures stabilize. Sea level rise is a particular long term concern as a result. The effects of ocean warming also include marine heatwaves, ocean stratification, deoxygenation, and changes to ocean currents. The ocean is also acidifying as it absorbs carbon dioxide from the atmosphere.

The ecosystems most immediately threatened by climate change are in the mountains, coral reefs, and the Arctic. Excess heat is causing environmental changes in those locations that exceed the ability of animals to adapt. Species are escaping heat by migrating towards the poles and to higher ground when they can. Sea level rise threatens coastal wetlands with flooding. Decreases in soil moisture in certain locations can cause desertification and damage ecosystems like the Amazon Rainforest. At 2 °C (3.6 °F) of warming, around 10% of species on land would become critically endangered.

Many adverse effects of climate change are not changes in the average conditions, but changes in the variation or the extremes of conditions. For example, the average sea level in a port might not be as important as the height of water during a storm surge (which causes flooding); the average rainfall in an area might not be as important as how frequent and severe droughts and extreme precipitation events become.

Reduce risk factors

See also: Climate risk

Adaptation can help decrease climate risk via the three interacting risk factors: hazards, vulnerability and exposure. It is not possible to directly reduce hazard risk (hazards are affected by current and future changes in climate). Instead, adaptation addresses risks of climate impacts from the interactions among climate-related hazards, and the exposure and vulnerability of affected human and ecological systems. Exposure refers to the presence of people, livelihoods, ecosystems, other assets etc. in places that could be negatively affected. Exposure can be decreased by retreating from areas with high climate risks, such as floodplains and by improving systems for early warnings and evacuations. Vulnerability is 'the propensity or predisposition to be adversely affected'. Vulnerability includes the ideas of sensitivity or susceptibility to harm and lack of capacity to cope and adapt. Vulnerability can be decreased in urban settings through using green garden spaces to reduce heat stress and food insecurity for low-income neighbourhoods.

The adverse impacts of climate hazards (typically natural hazards) may be reduced with the help of ecosystem-based adaptation. For instance, flooding may be prevented if mangroves have the ability to dampen storm energy. As such, protection of the mangrove ecosystem can be a form of adaptation. Insurance and livelihood diversification increase resilience and decrease vulnerability. Further actions to decrease vulnerability include strengthening social protection and building infrastructure more resistant to hazards.

Adaptive capacity

Adaptive capacity is the ability of a system (human, natural or managed) to adjust to climate change (including climate variability and extremes) to moderate potential damages, to take advantage of opportunities, or to cope with consequences. As a property, adaptive capacity is distinct from adaptation itself. Those societies that can respond to change quickly and successfully have a high adaptive capacity. High adaptive capacity does not necessarily translate into successful adaptation. For example, adaptive capacity in Western Europe is generally considered to be high, and the risks of warmer winters increasing the range of livestock diseases is well documented, but many parts of Europe were still badly affected by outbreaks of the Bluetongue virus in livestock in 2007. Adaptive capacity may include the capacity to produce, widely deploy and develop efficient and sustainable cooling technologies to protect populations against elevated temperatures.

The determinants of adaptive capacity include:

• Economic resources: Wealthier nations are better able to bear the costs of adaptation to climate change than poorer ones.
• Technology: Lack of technology can impede adaptation.
• Information and skills: Information and trained personnel are required to assess and implement successful adaptation options.
• Social infrastructure
• Institutions: Nations with well-developed social institutions are believed to have greater adaptive capacity than those with less effective institutions, typically developing nations and economies in transition.
• Equity: Some believe that adaptive capacity is greater where there are government institutions and arrangements in place that allow equitable access to resources.

Unmitigated climate change (i.e., future climate change without efforts to limit greenhouse gas emissions) would, in the long term, be likely to exceed the capacity of natural, managed and human systems to adapt.

It has been found that efforts to enhance adaptive capacity can help to reduce vulnerability to climate change. In many instances, activities to promote sustainable development can also act to enhance people's adaptive capacity to climate change. These activities can include: Improving access to resources, reducing poverty, lowering inequities of resources and wealth among groups, improving education and information, improving infrastructure, improving institutional capacity and efficiency, promoting local indigenous practices, knowledge, and experiences.

Others have suggested that certain forms of gender inequity should be addressed at the same time; for example women may have participation in decision-making, or be constrained by lower levels of education. Promoting free trade – e.g., through the removal of international trade barriers – could enhance adaptive capacity and contribute to economic growth.

Development interventions to increase adaptive capacity have tended not to result in increased agency for local people. This should play a more prominent part in future intervention planning because agency is a central factor in all other aspects of adaptive capacity. Asset holdings and the ability to convert these resources through institutional and market processes are central to agency.

Countries with limited economic resources, low levels of technology, poor information and skills, poor infrastructure, unstable or weak institutions, and inequitable empowerment and access to resources have little adaptive capacity and are highly vulnerable to climate change Developed nations, broadly speaking, have greater adaptive capacity than developing regions or countries in economic transition.

Adaptation responses by type of option

Many adaptation responses (also known as adaptation measures, strategies or solutions) exist and are used to help manage impacts and risks to people and nature.

Current adaptation tends to focus on near-term climate risks and is focused on particular sectors, such as water and agriculture, and regions, such as Africa and Asia. It is important to close existing gaps between actually implemented adaptation and the current needs (relative to today's climate) for reducing risks to a tolerable level. However, future adaptation also has to anticipate future risks of climate change. The effectiveness of some options may decrease with increasing global warming or they may become entirely unfeasible.

Adaptation responses can be grouped into four categories that all directly aim at reducing risks and exploiting opportunities:

1. Infrastructural and technological adaptation (including engineering, built environment, and high tech solutions);
2. Institutional adaptation (economic organizations, laws and regulation, government policies and programs).
3. Behavioural and cultural (individual and household strategies as well as social and community approaches);
4. Nature-based solutions (including ecosystem-based adaptation options)

Social adaptation processes (educational, informational and behavioural) that do not directly reduce risks are also sometimes considered as types of options.

Infrastructural and technological options

Wetland restoration in Australia

Checking contours in Monterey County strawberry fields, United States

Terraces, conservation tillage and conservation buffers save soil and improve water quality on this farm in Woodbury County in northwest Iowa, United States.

Built environment and technological options

Options that fall into the group of "built environment" include for example installing or upgrading infrastructure to protect against flooding, sea level rise, heatwaves and extreme heat, as well as infrastructure to respond to changed rainfall patterns in agriculture (e.g. irrigation infrastructure). These are explained further in the section below "by type of climate change impact".

Early warning system technologies

This section is an excerpt from Early warning system.[edit]

An early warning system is a warning system that can be implemented as a chain of information communication systems and comprises sensors, event detection and decision subsystems for early identification of hazards. They work together to forecast and signal disturbances that adversely affect the stability of the physical world, providing time for the response system to prepare for the adverse event and to minimize its impact.

To be effective, early warning systems need to actively involve the communities at risk, facilitate public education and awareness of risks, effectively disseminate alerts, and warnings and ensure there is constant state of preparedness. A complete and effective early warning system supports four main functions: risk analysis, monitoring and warning; dissemination and communication; and a response capability.

This section is an excerpt from Early warning system § For climate adaptation.[edit]

Because of changes in extreme weather and sea level rise, due to climate change, the UN has recommended early warning systems as key elements of climate change adaptation and climate risk management. Flooding, cyclones and other rapidly changing weather events can make communities in coastal areas, along floodzones and reliant on agriculture very vulnerable to extreme events. To this end the UN is running a partnership titled "Climate Risk and Early Warning Systems" to aid high risk countries with neglected warning systems in developing them.

Climate services

Climate services are systems for the delivery of the best available climate information to end-users in the most usable and accessible formats. Their objective is to support adaptation, mitigation and risk management decisions. A vast diversity of practices and products have been developed for the interpretation, analysis, and communication of climate data. They often combine different sources and different types of knowledge. Their aim is to fulfill a well-specified need. These climate services mark a shift from supply-driven (i.e. science-driven) information products to a demand-driven (i.e. decision-driven) production system that takes greater account of users’ needs. To do so they require different types of user–producer engagement, or co-design, depending on what the service aims to deliver.

Climate services are varied in their structure and objectives. They are set up to help users cope with current climate variability and limit the damage caused by climate-related disasters or be an important measure to reduce risks in a particular sector. Examples include: Copernicus Climate Change Service (C3S) which provides free and open access to climate data, tools and information which are used for a variety of purposes. Participatory Integrated Climate Services for Agriculture (PICSA) which is a participatory approach which combines historical climate data and forecasts with farmers’ local contextual knowledge.

Institutional options

Launching the Coastal City Adaptation Project in Quelimane, Mozambique

Coastal City Adaptation Project, in Quelimane city, Mozambique. It will improve Quelimane's preparation for events like floods, erosion, sea level rise and other weather and climate related events.

Institutional responses include zoning regulations, new building codes, new insurance schemes, and coordination mechanisms.

Policies have been identified as important tools for integrating issues of climate change adaptation. At national levels, adaptation strategies may be found in National Action Plans (NAPS ) and National Adaptation Programme of Action (NAPA, in developing countries), and/or in national policies and strategies on climate change. These are at different levels of development in different countries and in cities (progress is discussed in the section below "implementation").

Cities, states, and provinces often have considerable responsibility in land use planning, public health, and disaster management. Some have begun to take steps to adapt to threats intensified by climate change, such as flooding, bushfires, heatwaves, and rising sea levels.

Zoning regulations and building codes

Managing the codes or regulations that buildings must conform to is important for keeping people healthy and comfortable during extremes of hot and cold as well as protecting them from floods. There are many examples for achieving this, such as increasing the insulation values, adding solar shading, increasing natural ventilation or passive cooling, codes for green roofs to reduce urban heat island effects or requiring waterfront properties to have higher foundations. Land use zoning controls are also central to investment in urban development and reducing risks related to the areas threatened by floods and landslides.

Insurance

See also: Climate risk insurance

Insurance spreads the financial impact of flooding and other extreme weather events. There is an increasing availability of such options. For example, index-based insurance is a relatively new product which triggers payment when weather indices, such as precipitation or temperature, cross a threshold. It aims to help customers such as farmers deal with production risks. Access to reinsurance may be a form of increasing the resiliency of cities. Where there are failures in the private insurance market, the public sector can subsidize premiums. A study identified key equity issues for policy considerations:

• Transferring risk to the public purse does not reduce overall risk
• Governments can spread the cost of losses across time rather than space
• Governments can force home-owners in low risk areas to cross-subsidize the insurance premiums of those in high risk areas
• Cross-subsidization is increasingly difficult for private sector insurers operating in a competitive market
• Governments can tax people to pay for tomorrow's disaster.

Government-subsidized insurance, such as the U.S. National Flood Insurance Program, is criticized for providing a perverse incentive to develop properties in hazardous areas, thereby increasing overall risk. It is also suggested that insurance can undermine other efforts to increase adaptation, for instance through property level protection and resilience. This behavioral effect may be countered with appropriate land-use policies that limit new construction where current or future climate risks are perceived and/or encourage the adoption of resilient building codes to mitigate potential damages.

Behavioural and cultural options

Individuals and households play a central role in adaptation globally, with many examples documented particularly in the global south. Behavioural adaptation is change in the strategies, practices and actions that help to reduce risk, such as protecting homes from flooding, protecting crops from drought, and adopting different income earning activities.

Change in diets and food waste

Food waste spoilage is increased from exposure to higher temperatures and humidity, or from extreme events such as flooding and contamination. This can happen at different points in the food supply chain and can be a risk to food security and nutrition. Adaptation measures can review the production, processing and other handling practices of suppliers. Examples include further sorting to separate damaged products, drying the product for better storage or improved packaging. Other behaviour change options for retailers and consumers include acceptance of less-than-perfect fruit and vegetable appearance, redistribution of food surplus and lowered prices on nearly expired food.

Dietary change options (in regions with excess consumption of calories) include replacing meat and dairy foods with a higher share of plant-based foods. These have both mitigation and adaptation benefits. Plant-based options have much lower energy and water requirements. Adaptation options can investigate those dietary patterns that are better adjusted to the regional, socioeconomic and cultural context. People's preferences for foods are strongly shaped by social–cultural norms. Supporting policies such as subsidies, taxes, and marketing can also be important for dietary choice.

Change in livelihood strategies and their diversification

See also: Climate change adaptation § Changed rainfall patterns in agriculture

There is increasing understanding of agricultural adaptation options including changing planting time, or changing to crops and livestock that are more adapted to climate conditions and presence of pests, breeding more resilient crops and selecting genetically modified crops (given new technological options). These aim at improving food security and nutrition.

Nature-based solutions

Main articles: Ecosystem-based adaptation and Nature-based solutions

Ecosystems adapt to global warming depending on their resilience to climatic changes. Humans can help adaptation in ecosystems for biodiversity. Possible responses include increasing connectivity between ecosystems so that species can migrate on their own to more favorable climate conditions and assisting their migration through human transport of plants or animals. Protection and restoration of natural and semi-natural areas also helps build resilience, making it easier for ecosystems to adapt.

Many of the actions that promote adaptation in ecosystems, also help humans adapt via ecosystem-based adaptation and nature-based solutions. For instance, restoration of natural fire regimes makes catastrophic fires less likely, and reduces the human exposure to this hazard. Giving rivers more space allows for storage of more water in the natural system, making floods in inhabited areas less likely. The provision of green spaces and tree planting creates shade for livestock. There is a trade-off between agricultural production and the restoration of ecosystems in some areas.

Furthermore, humans can help ecosystems adapt to and become more resilient against climate change and its impacts. For instance, scientific research and development could be used to help coral reefs survive climate change.

Adaptation responses by type of climate change impact

Flooding and sea level rise

Flood protection for town of Ybbs along the river Donau

Further information: Flood control

Flooding can be in the form of urban flooding or coastal flooding which is exacerbated by sea level rise. In some areas there are also risks of glacial lake outburst floods.

There are a wide variety of adaptation options for flooding:

• Installing better flood defenses such as flood barriers, sea walls and increased pumping capacity
• Installing devices to prevent seawater from backflowing into storm drains
• Rainwater storage to deal with increased run-off from rainfall causing flooding – reducing paved areas or changing to water-permeable pavements, adding water-buffering vegetation, adding underground storage tanks, subsidizing household rain barrels t
• Raising pumps at wastewater treatment plants
• Buying out homeowners in flood-prone areas
• Raising street level to prevent flooding
• Flooding could be prevented by using and protecting mangroves
• Glacial lakes in danger of outburst flooding can have their moraines replaced with concrete dams to provide protection (which may also provide hydroelectric power).

Dealing with more frequent drenching rains may required increasing the capacity of stormwater systems, and separating stormwater from blackwater, so that overflows in peak periods do not contaminate rivers. One example is the SMART Tunnel in Kuala Lumpur.

New York City produced a comprehensive report for its Rebuilding and Resiliency initiative after Hurricane Sandy. Its efforts include not only making buildings less prone to flooding, but taking steps to reduce the recurrence of specific problems encountered during and after the storm: weeks-long fuel shortages even in unaffected areas due to legal and transportation problems, flooded health care facilities, insurance premium increases, damage to electricity and steam generation in addition to distribution networks, and flooding of subway and roadway tunnels.

Responding to sea level rise

This section is an excerpt from Sea level rise § Adaptation.[edit]

Cutting greenhouse gas emissions can slow and stabilize the rate of sea level rise after 2050. This would greatly reduce its costs and damages, but cannot stop it outright. So climate change adaptation to sea level rise is inevitable. The simplest approach is to stop development in vulnerable areas and ultimately move people and infrastructure away from them. Such retreat from sea level rise often results in the loss of livelihoods. The displacement of newly impoverished people could burden their new homes and accelerate social tensions.

It is possible to avoid or at least delay the retreat from sea level rise with enhanced protections. These include dams, levees or improved natural defenses. Other options include updating building standards to reduce damage from floods, addition of storm water valves to address more frequent and severe flooding at high tide, or cultivating crops more tolerant of saltwater in the soil, even at an increased cost. These options divide into hard and soft adaptation. Hard adaptation generally involves large-scale changes to human societies and ecological systems. It often includes the construction of capital-intensive infrastructure. Soft adaptation involves strengthening natural defenses and local community adaptation. This usually involves simple, modular and locally owned technology. The two types of adaptation may be complementary or mutually exclusive. Adaptation options often require significant investment. But the costs of doing nothing are far greater. One example would involve adaptation against flooding. Effective adaptation measures could reduce future annual costs of flooding in 136 of the world's largest coastal cities from $1 trillion by 2050 without adaptation to a little over $60 billion annually. The cost would be $50 billion per year. Some experts argue that retreat from the coast would have a lower impact on the GDP of India and Southeast Asia then attempting to protect every coastline, in the case of very high sea level rise.

To be successful, adaptation must anticipate sea level rise well ahead of time. As of 2023, the global state of adaptation planning is mixed. A survey of 253 planners from 49 countries found that 98% are aware of sea level rise projections, but 26% have not yet formally integrated them into their policy documents. Only around a third of respondents from Asian and South American countries have done so. This compares with 50% in Africa, and over 75% in Europe, Australasia and North America. Some 56% of all surveyed planners have plans which account for 2050 and 2100 sea level rise. But 53% use only a single projection rather than a range of two or three projections. Just 14% use four projections, including the one for "extreme" or "high-end" sea level rise. Another study found that over 75% of regional sea level rise assessments from the West and Northeastern United States included at least three estimates. These are usually RCP2.6, RCP4.5 and RCP8.5, and sometimes include extreme scenarios. But 88% of projections from the American South had only a single estimate. Similarly, no assessment from the South went beyond 2100. By contrast 14 assessments from the West went up to 2150, and three from the Northeast went to 2200. 56% of all localities were also found to underestimate the upper end of sea level rise relative to IPCC Sixth Assessment Report.

Heatwaves and extreme heat

Green roof

A 2020 study projects that regions inhabited by a third of the human population could become as hot as the hottest parts of the Sahara within 50 years without a change in patterns of population growth and without migration, unless greenhouse gas emissions are substantially reduced to a limit of 1.5 °C of warming. The most affected regions have little adaptive capacity as of 2020.

Projects to adapt to or to reduce heat include:

• Incentivizing lighter-colored roofs and paint of houses to reduce the heat island effect and use radiative cooling
  • Specific paint formulations for daytime radiative cooling that reflect up to 98.1% of sunlight could be used
• Changing to heat tolerant tree varieties
• Adding green roofs to deal with rainwater and heat
• The use and development of air conditioning and cooling systems
  • Adding air conditioning in public schools provides a cooler work place but can result in higher energy demand and greenhouse gas emissions unless solar energy is used.
• Solar-energy passive cooling systems for houses and/or refrigeration
  • In some cases designs that are relatively low-cost, do not use electrical components, are off-grid and chemically store solar energy for on-demand use

Changed rainfall patterns in agriculture

See also: Effects of climate change on agriculture § Adaptation

A significant effect of global climate change is the altering of global rainfall patterns, with certain effects on agriculture. Rainfed agriculture constitutes 80% of global agriculture. Many of the 852 million poor people in the world live in parts of Asia and Africa that depend on rainfall to cultivate food crops. Climate change will modify rainfall, evaporation, runoff, and soil moisture storage. Extended drought can cause the failure of small and marginal farms with resultant economic, political and social disruption, more so than this currently occurs.

Agriculture of any kind is strongly influenced by the availability of water. Changes in total seasonal precipitation or in its pattern of variability are both important. The occurrence of moisture stress during flowering, pollination, and grain-filling is harmful to most crops and particularly so to corn, soybeans, and wheat. Increased evaporation from the soil and accelerated transpiration in the plants themselves will cause moisture stress.

Adaptive ideas include:

• Taking advantage of global transportation systems to delivering surplus food to where it is needed (though this does not help subsistence farmers unless aid is given).
• Developing crop varieties with greater drought tolerance.
• Rainwater storage. For example, using small planting basins to 'harvest' water in Zimbabwe has been shown to boost maize yields, whether rainfall is abundant or scarce. And in Niger, they have led to three or fourfold increases in millet yields.
• Falling back from crops to wild edible fruits, roots and leaves. Promoting the growth of forests can provide these backup food supplies, and also provide watershed conservation, carbon sequestration, and aesthetic value.

Climate change can threaten food security and water security. Food systems can be adapted to enhance food security and to prevent future negative impacts from climate change.

More spending on irrigation

The demand for water for irrigation is projected to rise in a warmer climate, bringing increased competition between agriculture—already the largest consumer of water resources in semi-arid regions—and urban as well as industrial users. Falling water tables and the resulting increase in the energy needed to pump water will make the practice of irrigation more expensive, particularly when with drier conditions more water will be required per acre. Other strategies will be needed to make the most efficient use of water resources. For example, the International Water Management Institute has suggested five strategies that could help Asia feed its growing population in light of climate change. These are: Modernizing existing irrigation schemes to suit modern methods of farming; supporting farmers' efforts to find their own water supplies, by tapping into groundwater in a sustainable way; Looking beyond conventional "Participatory Irrigation Management" schemes, by engaging the private sector; Expanding capacity and knowledge; Investing outside the irrigation sector.

Drought and desertification

Reforestation activities in Praslin, Seychelles

Reforestation is one of the ways to stop desertification fueled by anthropogenic climate change and non sustainable land use. One of the most important projects is the Great Green Wall that should stop the expansion of Sahara desert to the south. By 2018 only 15% of it is accomplished, but there are already many positive effects, which include: "Over 12 million acres (5 million hectares) of degraded land has been restored in Nigeria; roughly 30 million acres of drought-resistant trees have been planted across Senegal; and a whopping 37 million acres of land has been restored in Ethiopia – just to name a few of the states involved." "Many groundwater wells [were] refilled with drinking water, rural towns with additional food supplies, and new sources of work and income for villagers, thanks to the need for tree maintenance."

Changed living conditions leading to migration pressures

Of humans

See also: Climate migrant and Effects of climate change § Displacement and migration

The Government of Kiribati is addressing the threats of climate change to Kiribati, under the Kiribati Adaptation Program. Island nations in the Pacific are particularly vulnerable to sea level rise.

Migration can be seen as adaptation: people may be able to generate more income, diversify livelihoods, and spread climate risk. This contrasts with two other frames around migration and environmental change: migration as a human rights issue and migration as a security issue. In the human right's frame, normative implications include developing protection frameworks for migrants, whereas increased border security may be an implication of framing migration as a national security issue. Sometimes these approaches are combined for the development of solutions (laws and policies) that aim to be both viable, taking national concerns into account, and in accordance with human rights. Furthermore, there may also be economic aspects of migration – high levels of migration and emigration of skilled workers – that decision-makers in both the – distant or nearby – host country and the country of origin may consider. Vice versa, climate change could also exacerbate economic insecurity or political instability as causes for migration beyond temperatures and extreme weather events.

Would-be migrants often need access to social and financial capital, such as support networks in the chosen destination and the funds or physical resources to be able to move. Migration is frequently the last adaptive response households will take when confronted with environmental factors that threaten their livelihoods, and mostly resorted to when other mechanisms to cope have proven unsuccessful.

Migration events are multi-causal, with the environment being just a factor amongst many. Many discussions around migration are based on projections, while relatively few use current migration data. Migration related to sudden events like hurricanes, heavy rains, floods, and landslides is often short-distance, involuntary, and temporary. Slow-impact events, such as droughts and slowly rising temperatures, have more mixed effects. People may lose the means to migrate, leading to a net decrease in migration. The migration that does take place is seen as voluntary and economically motivated.

Focusing on climate change as the issue may frame the debate around migration in terms of projections, causing the research to be speculative. Migration as tool for climate change adaptation is projected to be a more pressing issue in the decade to come. In Africa, specifically, migrant social networks can help to build social capital to increase the social resilience in the communities of origin and trigger innovations across regions by the transfer of knowledge, technology, remittances and other resources.

In Africa, Mozambique and Zimbabwe are clear examples of adaptation strategies because they have implemented relocation policies that have reduced the exposure of populations and migrants to disaster. Tools can be put in place that limit forced displacement after a disaster; promote employment programs, even if only temporary, for internally displaced people or establish funding plans to ensure their security; to minimize the vulnerability of populations from risk areas. This can limit the displacement caused by environmental shocks and better channel the positive spillovers (money transfers, experiences, etc.) from the migration to the origin countries/communities.

Relocation from the effects of climate change has been brought to light more and more over the years from the constant increasing effects of climate change in the world. Coastal homes in the U.S. are in danger from climate change, this is leading residents to relocate to areas that are less affected. Flooding in coastal areas and drought have been the main reasons for relocation.

This section is an excerpt from Climate migration.[edit]

Climate migration is a subset of climate-related mobility that refers to movement driven by the impact of sudden or gradual climate-exacerbated disasters, such as "abnormally heavy rainfalls, prolonged droughts, desertification, environmental degradation, or sea-level rise and cyclones". Gradual shifts in the environment tend to impact more people than sudden disasters. The majority of climate migrants move internally within their own countries, though a smaller number of climate-displaced people also move across national borders.

Of ecosystems

Assisted migration is the act of moving plants or animals to a different habitat. The destination habitat may or may not have once previously held the species; the only requirement is the destination habitat must provide the bioclimatic requirements to support the species. The goal of assisted migration is to remove the species from a threatening environment and give them a chance to survive and reproduce in an environment that does not pose an existential threat to the species.

In recent years, assisted migration has been presented as a potential solution to the climate change crisis that has changed environments faster than natural selection can adapt to. While assisted migration has the potential to allow species that have poor natural dispersal abilities to avoid extinction, it has also sparked intense debate over the possibility of the introduction of invasive species and diseases into previously healthy ecosystems. Despite these debates, scientists and land managers have already begun the process of assisted migration for certain species.

In the North American context, assisted migration is most often discussed in the context of the relocalization of the continent's forests. In the late 2000s and early 2010s, the Canadian provinces of Alberta and British Columbia modified their tree reseeding guidelines to account for the northward movement of forest's optimal ranges. British Columbia even gave the green light for the relocation of a single species, the Western Larch, 1000 km northward.

Costs

Economic costs

The economic costs of adaptation to climate change will depend in large part on how much the climate changes: higher levels of warming lead to considerably higher costs. Globally, adaptation is likely to cost billions of dollars annually for the next several decades. Adaptation costs are estimated at "15 to 411 billion USD yr−1 for climate change impacts out to 2030, with the majority of estimates being well above 100 billion." Because these costs are considerably higher than the finance available, there is an 'adaptation gap', which is especially pressing in developing countries. This gap is widening and forms a major barrier to adaptation.

An extensive research literature assesses options for responses to global warming. Much of this literature addresses the potential economic costs associated with different strategies, and studies generally focus on adaptation in developing countries or within a sector. This means that for many specific adaptation options in specific contexts, it is clear that the investment will be lower than the avoided damages, but global estimates have considerable uncertainty. The Asian Development Bank has a series of studies on the Economics of Climate Change in the Asia-Pacific region. These studies provide cost analysis of both adaptation and mitigation measures. The WEAP (Water Evaluation And Planning system) assists water resources researchers and planners in assessing impacts of and adaptations to climate change. The United Nations Development Programme's Climate Change Adaptation Portal includes studies on climate change adaptation in Africa, Europe and Central Asia, and Asia and the Pacific.

In addition to the direct costs associated with spending on adaptation and mitigation there is also research indicating the cost associated with diverting resources away from productive sources towards these adaptation purposes. Such a diversion is termed the adaptive investment effect (AIE) and evidence suggests that the impact of investment on economic growth is reduced by around 30% in areas which invest heavily in adaptive technologies.

Cost benefit analysis

As of 2007 there was still a lack of comprehensive, global cost and benefit estimates for adaptation. Studies were noted that provided cost estimates of adaptation at regional level, e.g., for sea-level rise. A number of adaptation measures were identified as having high benefit-cost ratios.

International finance

Main articles: Climate finance and The Adaptation Fund

The United Nations Framework Convention on Climate Change, under Article 11, incorporates a financial mechanism to developing country parties to support them with adaptation. Until 2009, three funds existed under the UNFCCC financial mechanism. The Special Climate Change Fund (SCCF) and the Least Developed Countries Fund (LDCF) are administered by the Global Environmental Facility. The Adaptation Fund was established a result of negotiations during COP15 and COP16 and is administered by its own Secretariat. Initially, when the Kyoto Protocol was in operation, the Adaptation Fund was financed by a 2% levy on the Clean Development Mechanism (CDM).

At the 2009 Copenhagen Summit, nations committed to the goal of sending $100 billion per year to developing countries for climate change mitigation and adaptation by 2020. The Green Climate Fund was created in 2010 as one of the channels for mobilizing this climate finance. At the 2015 Paris conference, it was clarified that the $100 billion per year should involve a balanced split between mitigation and adaptation. As of December 2020, the promised $100 billion per year had not been fully delivered, and most developing country finance was still targeted towards mitigation, with adaptation only receiving a 21% share of the public finance provided in 2020.

Additionality

A key and defining feature of international adaptation finance is its premise on the concept of additionality. This reflects the linkages between adaptation finance and other levels of development aid. Many developed countries already provide international aid assistance to developing countries to address challenges such as poverty, malnutrition, food insecurity, availability of drinking water, indebtedness, illiteracy, unemployment, local resource conflicts, and lower technological development. Climate change threatens to exacerbate or stall progress on fixing some of these pre-existing problems, and creates new problems. To avoid existing aid being redirected, additionality refers to the extra costs of adaptation.

The four main definitions of additionality are:

1. Climate finance classified as aid, but additional to (over and above) the Millennium Development Goals;
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.

A criticism of additionality is that it encourages business as usual that does not account for the future risks of climate change. Some advocates have thus proposed integrating climate change adaptation into poverty reduction programs.

From 2010 to 2020, Denmark increased its global warming adaptation aid 33%, from 0.09% of GDP to 0.12% of GDP, but not by additionality. Instead, the aid was subtracted from other foreign assistance funds. Politiken wrote: "Climate assistance is taken from the poorest."

Economic aspects and vulnerability

Climate change vulnerability is defined as the "propensity or predisposition to be adversely affected" by climate change. It can apply to humans but also to natural systems (ecosystems). Human and ecosystem vulnerability are interdependent. Climate change vulnerability encompasses "a variety of concepts and elements, including sensitivity or susceptibility to harm and lack of capacity to cope and adapt". Vulnerability is a component of climate risk.

Autonomous and planned adaptation

Autonomous adaptation are adaptations that are reactive to climatic stimuli, and are done as a matter of course without the intervention of a public agency. Planned adaptation can be reactive or anticipatory, i.e., undertaken before impacts are apparent. Some studies suggest that human systems have considerable capacity to adapt autonomously. Others point to constraints on autonomous adaptation, such as limited information and access to resources Relying on autonomous adaptation to climate change can result in substantial ecological, social, and economic costs. In their view, these costs could largely be avoided with planned adaptation.

Regions

Developing countries tend to be more vulnerable to climate change than developed countries. Based on then-current development trends (in 2001), it was predicted that few developing countries would have the capacity to efficiently adapt to climate change.

• Africa: Africa's major economic sectors have been vulnerable to observed climate variability. This vulnerability was judged to have contributed to Africa's weak adaptive capacity, resulting in Africa having high vulnerability to future climate change. It was thought likely that projected sea-level rise would increase the socio-economic vulnerability of African coastal cities.
• Asia: Climate change can result in the degradation of permafrost in boreal Asia, worsening the vulnerability of climate-dependent sectors, and affecting the region's economy.
• Australia and New Zealand: In Australia and New Zealand, most human systems have considerable adaptive capacity. With medium confidence, some Indigenous communities were judged to have low adaptive capacity.
• Europe: The adaptation potential of socioeconomic systems in Europe was judged to be relatively high in 2001. This was attributed to Europe's high GNP, stable growth, stable population, and well-developed political, institutional, and technological support systems.

• Latin America: The adaptive capacity of socioeconomic systems in Latin America was very low, particularly in regard to extreme weather events, and that the region's vulnerability was high.
• Polar regions: Anisimov et al. (2001) concluded that:
  • within the Antarctic and Arctic, at localities where water was close to melting point, socioeconomic systems were particularly vulnerable to climate change.
  • the Arctic would be extremely vulnerable to climate change. Anisimov et al. (2001) predicted that there would be major ecological, sociological, and economic impacts in the region.
• Small islands: Mimura et al. (2007) concluded, with very high confidence, that small islands were particularly vulnerable to climate change.

Partly this was attributed to their low adaptive capacity and the high costs of adaptation in proportion to their GDP.

Systems and sectors

• Coasts and low-lying areas: Societal vulnerability to climate change is largely dependent on development status. Developing countries lack the necessary financial resources to relocate those living in low-lying coastal zones, making them more vulnerable to climate change than developed countries. On vulnerable coasts, the costs of adapting to climate change are lower than the potential damage costs.
• Industry, settlements and society:
  • At the scale of a large nation or region, at least in most industrialized economies, the economic value of sectors with low vulnerability to climate change greatly exceeds that of sectors with high vulnerability. Additionally, the capacity of a large, complex economy to absorb climate-related impacts, is often considerable. Consequently, estimates of the aggregate damages of climate change – ignoring possible abrupt climate change – are often rather small as a percentage of economic production. On the other hand, at smaller scales, e.g., for a small country, sectors and societies might be highly vulnerable to climate change. Potential climate change impacts might therefore amount to very severe damages.
  • Vulnerability to climate change depends considerably on specific geographic, sectoral and social contexts. In their view, these vulnerabilities are not reliably estimated by large-scale aggregate modelling.

Challenges

Differing time scales

Adaptation can occur in anticipation of change (anticipatory adaptation), or be a response to those changes (reactive adaptation). For example, artificial snow-making in the European Alps responds to current climate trends, whereas construction of the Confederation Bridge in Canada at a higher elevation takes into account the effect of future sea-level rise on ship clearance under the bridge.

Additionally, effective adaptive policy can be difficult to implement because policymakers are rewarded more for enacting short-term change, rather than long-term planning. Since the impacts of climate change are generally not seen in the short term, policymakers have less incentive to act. Furthermore, climate change is occurring on a global scale, which requires a global framework for adapting to and combating climate change. The vast majority of climate change adaptation and mitigation policies are being implemented on a more local scale because different regions must adapt differently and because national and global policies are often more challenging to enact.

Maladaptation

Much adaptation takes place in relation to short-term climate variability, however this may cause maladaptation to longer-term climatic trends. For example, the expansion of irrigation in Egypt into the Western Sinai desert after a period of higher river flows is a maladaptation when viewed in relation to the longer term projections of drying in the region. Adaptations at one scale can also create externalities at another by reducing the adaptive capacity of other actors. This is often the case when broad assessments of the costs and benefits of adaptation are examined at smaller scales and it is possible to see that whilst the adaptation may benefit some actors, it has a negative effect on others.

Limits to adaptation including traditional strategies

People have always adapted to climatic changes and some community coping strategies already exist, for example changing sowing times or adopting new water-saving techniques. Traditional knowledge and coping strategies must be maintained and strengthened, otherwise adaptive capacity may be weakened as local knowledge of the environment is lost. Strengthening these local techniques and building upon them also makes it more likely that adaptation strategies will be adopted, as it creates more community ownership and involvement in the process. In many cases this will not be enough to adapt to new conditions which are outside the range of those previously experienced, and new techniques will be needed. The incremental adaptations which have been implemented become insufficient as the vulnerabilities and risks of climate change increase, this causes a need for transformational adaptations which are much larger and costlier. Current development efforts are increasingly focusing on community-based climate change adaptation, seeking to enhance local knowledge, participation and ownership of adaptation strategies.

Incentivising private investment in adaptation

Climate change adaptation is a much more complex investment area than mitigation, mainly because of the lack of a well-defined income stream or business case with an attractive return on investment on projects. There are several rather specific challenges for private investment:

• adaptation is often needed in non-market sectors or is focused on public goods that benefit many (therefore there is a shortage of projects that are attractive to the private sector);
• there is a mismatch between the timing of the investment where it is needed in the short-term and the benefits, which for adaptation are generally in the medium- or long-term (future returns are less attractive to investors than short-term returns);
• there is a lack of information about investment opportunities, especially regarding uncertainties associated with future impacts and benefits (which are key considerations when returns may accrue over longer timeframes);
• there are also gaps in human resources and capacities to design adaptation projects and understand financial implications of legal, economic and regulatory frameworks (which are often less developed).

However, there is considerable innovation in this area, increasing the potential for private sector finance to play a larger role in closing the adaptation finance gap. Economists state that climate adaptation initiatives should be an urgent priority for business investment.

Implementation

By country and city

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

A 2020 United Nations report found that while 72% of countries had a high level adaptation instrument – such as a plan, policy or strategy – relatively few had progressed to the tangible implementation of projects. At least not to the point where the climate risk their populations are exposed to had been significantly reduced.

A survey of 812 global cities found that while 93% reported they are at risk from climate change, 43% did not have an adaptation plan in 2021, and 41% of cities had not carried out a climate risk and vulnerability assessment.

Global goals

Sustainable Development Goal 13, which was set in 2015, aims to strengthen countries' resilience and adaptive capacities to climate-related issues. This adjustment includes many areas such as infrastructure, agriculture and education. The Paris Agreement includes several provisions for adaptation. It seeks to promote the idea of global responsibility, improve communication via the adaptation component of the Nationally Determined Contributions, and includes an agreement that developed countries should provide some financial support and technology transfer to promote adaptation in more vulnerable countries.

The United Nations estimates for Africa, considering population growth, yearly funding of $1.3 trillion would be needed to achieve the Sustainable Development Goals in Africa. The International Monetary Fund also estimates that $50 billion may be needed only to cover the expenses of climate adaptation.

See also

• Adaptation in Africa
• Climate bond
• Climate finance
• Climate justice
• Climate Vulnerability Monitor
• Effects of climate change

External links

• The Intergovernmental Panel on Climate Change (IPCC) Working Group II assesses the scientific literature on adaptation: https://www.ipcc.ch/working-group/wg2/
• The weADAPT platform encourages the sharing of experiences from adaptation projects to accelerate learning and climate action.
• The UN-CECAR research and development of courses on climate change and adaptation
• The UNFCCC has a database on local adaptation measures and information on the international climate negotiations
• UNDP climate adaptation projects
• Adaptation (PBS series) Climate researcher Alizé Carrère explores how communities around the world are adapting to change