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.
Sea surface temperature since 1979 in the extrapolar region (between 60 degrees south and 60 degrees north latitude)
Sea surface temperature (SST), or ocean surface temperature, is the
ocean temperature close to the surface. The exact meaning of surface varies in the literature and in practice. It is usually between 1 millimetre (0.04 in) and 20 metres (70 ft) below the
sea surface. Sea surface temperatures greatly modify
air masses in the
Earth's atmosphere within a short distance of the shore. Local areas of heavy
snow can form in
bands downwind of warm water bodies within an otherwise cold air mass. Warm sea surface temperatures can develop and
strengthen cyclones over the ocean. Tropical cyclones can also cause a cool wake. This is due to turbulent mixing of the upper 30 metres (100 ft) of the ocean. Sea surface temperature changes during the day. This is like the air above it, but to a lesser degree. There is less variation in sea surface temperature on breezy days than on calm days. The
thermohaline circulation has a major impact on average sea surface temperature throughout most of the world's oceans.
Coastal SSTs can cause offshore winds to generate
upwelling, which can significantly cool or warm nearby landmasses, but shallower waters over a
continental shelf are often warmer. Onshore winds can cause a considerable warm-up even in areas where upwelling is fairly constant, such as the northwest coast of
South America. Its values are important within
numerical weather prediction as the SST influences the atmosphere above, such as in the formation of
sea breezes and
sea fog.
It is very likely that global mean sea surface temperature increased by 0.88°C between 1850–1900 and 2011–2020 due to
global warming, with most of that warming (0.60°C) occurring between 1980 and 2020. The temperatures over land are rising faster than
ocean temperatures. This is because the
ocean absorbs about 90% of
excess heat generated by
climate change. (Full article...)
An image of the Earth's cloud cover, which is the amount of sky obscured by
clouds, based largely on observations from
NASA's
Moderate Resolution Imaging Spectroradiometer (MODIS) on board the
Terra satellite. Clouds play multiple critical roles in the
climate system. In particular, being bright objects in the visible part of
sunlight, they efficiently reflect light to space and thus contribute to the cooling of the planet.
Image 5CO2 concentrations over the last 800,000 years as measured from ice cores (blue/green) and directly (black) (from Causes of climate change)
Image 6Energy 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 7A diagram which shows where the extra heat retained on Earth due to the energy imbalance is going. (from Causes of climate change)
Image 8CO2 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 9This 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 12Earth'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 14The 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 15Photosynthesis changes sunlight into chemical energy, splits water to liberate O2, and fixes CO2 into sugar. (from Carbon dioxide in Earth's atmosphere)
Image 16The 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 17Erratics, 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 18Over 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 19Earth'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 21Global 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 23Between 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 26CO2 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 27Terms 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 28Since 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 31The 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 33Scientific 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 35Carbon 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 36Annual 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 39Warming 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 40Sea 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 41Mean 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)
Image 42The US, China and Russia have cumulatively contributed the greatest amounts of CO2 since 1850. (from Carbon dioxide in Earth's atmosphere)
Image 44Atmospheric CO2 concentration measured at
Mauna Loa Observatory in Hawaii from 1958 to 2023 (also called the
Keeling Curve). The rise in CO2 over that time period is clearly visible. The concentration is expressed as μmole per mole, or
ppm. (from Carbon dioxide in Earth's atmosphere)
Image 47Modeled 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 48Greenhouse 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 49A
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 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 53Schematic drawing of Earth's excess heat inventory and energy imbalance for two recent time periods. (from Earth's energy budget)
Image 54The 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 55Drivers 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 56Cumulative land-use change contributions to CO2 emissions, by region. (from Causes of climate change)
Image 57Air 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)
Animation of Modeled Climate-Induced
Glacier Change in
Glacier National Park, 1850- 2100. The simulation reflects the predicted exponential rise in atmospheric
carbon dioxide (CO2) concentrations, a 2xCO2 "global warming" scenario, with a concurrent warming of 2-3 degrees centigrade (4-5 degrees Fahrenheit) by the year 2050. In addition it assumes that
precipitation, primarily in the form of
rain, will increase over the same time period about 10 percent (based on the research of Dr. Steven Running, University of Montana).
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