Many climate change impacts have been felt in recent years, with 2023 the warmest on record at +1.48 °C (2.66 °F) since regular tracking began in 1850. Additional warming will increase these impacts and can trigger tipping points, such as melting all of the Greenland ice sheet. Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2 °C". However, with pledges made under the Agreement, global warming would still reach about 2.7 °C (4.9 °F) by the end of the century. Limiting warming to 1.5 °C will require halving emissions by 2030 and achieving net-zero emissions by 2050.
Smog and a sunny day within a 10-day interval in Fanhe, China
Smog, or smoke fog, is a type of intense air pollution. The word "smog" was coined in the early 20th century, and is a portmanteau of the words smoke and fog to refer to smoky fog due to its opacity, and odor. The word was then intended to refer to what was sometimes known as pea soup fog, a familiar and serious problem in London from the 19th century to the mid-20th century, where it was commonly known as a London particular or London fog. This kind of visible air pollution is composed of nitrogen oxides, sulfur oxide, ozone, smoke and other particulates. Man-made smog is derived from coal combustion emissions, vehicular emissions, industrial emissions, forest and agricultural fires and photochemical reactions of these emissions.
Smog is often categorized as being either summer smog or winter smog. Summer smog is primarily associated with the photochemical formation of ozone. During the summer season when the temperatures are warmer and there is more sunlight present, photochemical smog is the dominant type of smog formation. During the winter months when the temperatures are colder, and atmospheric inversions are common, there is an increase in coal and other fossil fuel usage to heat homes and buildings. These combustion emissions, together with the lack of pollutant dispersion under inversions, characterize winter smog formation. Smog formation in general relies on both primary and secondary pollutants. Primary pollutants are emitted directly from a source, such as emissions of sulfur dioxide from coal combustion. Secondary pollutants, such as ozone, are formed when primary pollutants undergo chemical reactions in the atmosphere.
Photochemical smog, as found for example in Los Angeles, is a type of air pollution derived from vehicular emission from internal combustion engines and industrial fumes. These pollutants react in the atmosphere with sunlight to form secondary pollutants that also combine with the primary emissions to form photochemical smog. In certain other cities, such as Delhi, smog severity is often aggravated by stubble burning in neighboring agricultural areas since the 1980s. The atmospheric pollution levels of Los Angeles, Beijing, Delhi, Lahore, Mexico City, Tehran and other cities are often increased by an inversion that traps pollution close to the ground. The developing smog is usually toxic to humans and can cause severe sickness, a shortened life span, or premature death. (Full article...)
The Ocean Circulation Conveyor Belt. The ocean plays a major role in the distribution of the planet's heat through deep sea circulation. This simplified illustration shows this "conveyor belt" circulation.
She was the longest-serving administrator in the history of the EPA, staying through both terms of the Clinton presidency. During her tenure, she reorganized the agency's enforcement structure and oversaw two new programs designed to create flexible partnerships with industry as an alternative to traditional regulation. She started a successful program to deal with contaminated lands in urban areas. She took the lead within the administration in defending existing environmental laws and budgets and was the driving force behind a stringent tightening of air quality standards that led to a prolonged political and legal battle. (Full article...)
The following are images from various climate-related articles on Wikipedia.
Image 1Scientific consensus on causation:Academic studies of scientific agreement on human-caused global warming among climate experts (2010–2015) reflect that the level of consensus correlates with expertise in climate science. A 2019 study found scientific consensus to be at 100%, and a 2021 study concluded that consensus exceeded 99%. Another 2021 study found that 98.7% of climate experts indicated that the Earth is getting warmer mostly because of human activity. (from History of climate change science)
Image 4Between 1850 and 2019 the Global Carbon Project estimates that about 2/3rds of excess carbon dioxide emissions have been caused by burning fossil fuels, and a little less than half of that has stayed in the atmosphere. (from Carbon dioxide in Earth's atmosphere)
Image 6Warming influence of atmospheric greenhouse gases has nearly doubled since 1979, with carbon dioxide and methane being the dominant drivers. (from Causes of climate change)
Image 7Sea ice reflects 50% to 70% of incoming sunlight, while the ocean, being darker, reflects only 6%. As an area of sea ice melts and exposes more ocean, more heat is absorbed by the ocean, raising temperatures that melt still more ice. This is a positive feedback process. (from Causes of climate change)
Image 10The rate of global tree cover loss has approximately doubled since 2001, to an annual loss approaching an area the size of Italy. (from Causes of climate change)
Image 11CO2 sources and sinks since 1880. While there is little debate that excess carbon dioxide in the industrial era has mostly come from burning fossil fuels, the future strength of land and ocean carbon sinks is an area of study. (from Causes of climate change)
Image 14Air pollution has substantially increased the presence of aerosols in the atmosphere when compared to the preindustrial background levels. Different types of particles have different effects, but overall, cooling from aerosols formed by sulfur dioxide emissions has the overwhelming impact. However, the complexity of aerosol interactions in atmospheric layers makes the exact strength of cooling very difficult to estimate. (from Causes of climate change)
Image 15Since the 1980s, global average surface temperatures during a given decade have almost always been higher than the average temperature in the preceding decade. (from History of climate change science)
Image 16Drivers of climate change from 1850–1900 to 2010–2019. There was no significant contribution from internal variability or solar and volcanic drivers. (from Causes of climate change)
Image 18Modeled simulation of the effect of various factors (including GHGs, Solar irradiance) singly and in combination, showing in particular that solar activity produces a small and nearly uniform warming, unlike what is observed. (from History of climate change science)
Image 20The growth in Earth's energy imbalance from satellite and in situ measurements (2005–2019). A rate of +1.0 W/m2 summed over the planet's surface equates to a continuous heat uptake of about 500 terawatts (~0.3% of the incident solar radiation). (from Earth's energy budget)
Image 27Greenhouse gases allow sunlight to pass through the atmosphere, heating the planet, but then absorb and redirect the infrared radiation (heat) the planet emits (from Carbon dioxide in Earth's atmosphere)
Image 28A diagram which shows where the extra heat retained on Earth due to the energy imbalance is going. (from Causes of climate change)
Image 29Energy flows between space, the atmosphere, and Earth's surface. Rising greenhouse gas levels are contributing to an energy imbalance. (from Causes of climate change)
Image 30Earth's energy balance and imbalance, showing where the excess energy goes: Outgoing radiation is decreasing owing to increasing greenhouse gases in the atmosphere, leading to Earth's energy imbalance of about 460 TW. The percentage going into each domain of the climate system is also indicated. (from Earth's energy budget)
Image 33Schematic drawing of Earth's excess heat inventory and energy imbalance for two recent time periods. (from Earth's energy budget)
Image 34Earth's energy budget (in W/m2) determines the climate. It is the balance of incoming and outgoing radiation and can be measured by satellites. The Earth's energy imbalance is the "net absorbed" energy amount and grew from +0.6 W/m2 (2009 est.) to above +1.0 W/m2 in 2019. (from Earth's energy budget)
Image 35CO2 concentrations over the last 800,000 years as measured from ice cores (blue/green) and directly (black) (from Causes of climate change)
Image 36This diagram of the fast carbon cycle shows the movement of carbon between land, atmosphere, and oceans in billions of metric tons of carbon per year. Yellow numbers are natural fluxes, red are human contributions, white are stored carbon. (from Carbon dioxide in Earth's atmosphere)
Image 37The rising accumulation of energy in the oceanic, land, ice, and atmospheric components of Earth's climate system since 1960. (from Earth's energy budget)
Image 39Over 400,000 years of ice core data: Graph of CO2 (green), reconstructed temperature (blue) and dust (red) from the Vostok ice core (from Carbon dioxide in Earth's atmosphere)
Image 40Photosynthesis changes sunlight into chemical energy, splits water to liberate O2, and fixes CO2 into sugar. (from Carbon dioxide in Earth's atmosphere)
Image 44CO2 reduces the flux of thermal radiation emitted to space (causing the large dip near 667 cm−1), thereby contributing to the greenhouse effect. (from Carbon dioxide in Earth's atmosphere)
Image 45Terms like "climate emergency" and climate crisis" have often been used by activists, and are increasingly found in academic papers. (from History of climate change science)
Image 46Cumulative land-use change contributions to CO2 emissions, by region. (from Causes of climate change)
Image 47Annual CO2 flows from anthropogenic sources (left) into Earth's atmosphere, land, and ocean sinks (right) since year 1960. Units in equivalent gigatonnes carbon per year. (from Carbon dioxide in Earth's atmosphere)
Image 49Erratics, boulders deposited by glaciers far from any existing glaciers, led geologists to the conclusion that climate had changed in the past. (from History of climate change science)
Image 50Observed temperature from NASA vs the 1850–1900 average used by the IPCC as a pre-industrial baseline. The primary driver for increased global temperatures in the industrial era is human activity, with natural forces adding variability. (from Causes of climate change)
Image 51A Sankey diagram illustrating a balanced example of Earth's energy budget. Line thickness is linearly proportional to relative amount of energy. (from Earth's energy budget)
Image 52The impact of the greenhouse effect on climate was presented to the public early in the 20th century, as succinctly described in this 1912 Popular Mechanics article. (from History of climate change science)
Image 55Carbon dioxide observations from 2008 to 2017 showing the seasonal variations and the difference between northern and southern hemispheres (from Carbon dioxide in Earth's atmosphere)
Image 56Global average temperatures show that the Medieval Warm Period was not a planet-wide phenomenon, and that the Little Ice Age was not a distinct planet-wide time period but rather the end of a long temperature decline that preceded recent global warming. (from Temperature record of the last 2,000 years)
Image 57Mean temperature anomalies during the period 1965 to 1975 with respect to the average temperatures from 1937 to 1946. This dataset was not available at the time. (from History of climate change science)
... that global warming millions of years ago put seas in a spin? The circulation of the deep oceans reversed abruptly some 55 million years ago, according to a study of fossilized sea creatures. This rings alarm bells about today's climate change, because the reversal coincided with a period of global warming driven by greenhouse gases." Article on Nature News
Plant Productivity in a Warming World: The past decade is the warmest on record since instrumental measurements began in the 1880s. Previous research suggested that in the '80s and '90s, warmer global temperatures and higher levels of precipitation—factors associated with climate change—were generally good for plant productivity. An updated analysis published this week in Science indicates that as temperatures have continued to rise, the benefits to plants are now overwhelmed by longer and more frequent droughts. High-resolution data from the Moderate-Resolution Imaging Spectroradiometer, or MODIS, indicate a net decrease in net primary production (NPP) from 2000-2009, as compared to the previous two decades. This narrated video gives an overview of NPP and the carbon cycle.
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