Global surface temperature

Global surface temperature (GST) is the average temperature of <a href="/facts/Earth/HLLmDfj0">Earth</a>'s surface. More precisely, it is the <a href="/facts/Weighted_average/VHyJfPxb">weighted average</a> of the temperatures over the <a href="/facts/Ocean/8W8lYgjD">ocean</a> and land. The former is also called <a href="/facts/Sea_surface_temperature/D9bNcRxX">sea surface temperature</a> and the latter is called <a href="/facts/Surface_air_temperature/p44AF78I">surface air temperature</a>. Temperature data comes mainly from <a href="/facts/Weather_station/JMCQtA74">weather stations</a> and <a href="/facts/Satellite/PTX8c68t">satellites</a>. To estimate data in the distant past, <a href="/facts/Proxy_data/kuCVBpBL">proxy data</a> can be used for example from <a href="/facts/Tree_rings/bXK8Km2M">tree rings</a>, <a href="/facts/Coral/j7fBLrpw">corals</a>, and <a href="/facts/Ice_core/QnzraAoN">ice cores</a>. Observing the rising GST over time is one of the many lines of evidence supporting the <a href="/facts/Scientific_consensus_on_climate_change/HUQURQGn">scientific consensus on climate change</a>, which is that <a href="/facts/Climate_change/rEN4BDE7">human activities are causing climate change</a>. Alternative terms for the same thing are global mean surface temperature (GMST) or global average surface temperature. 
Series of reliable temperature measurements in some regions began in the 1850—1880 time frame (this is called the instrumental temperature record). The longest-running temperature record is the <a href="/facts/Central_England_temperature/w2ppUzn9">Central England temperature</a> data series, which starts in 1659. The longest-running quasi-global records start in 1850. For temperature measurements in the <a href="/facts/Upper_atmosphere/5yH29VP8">upper atmosphere</a> a variety of methods can be used. This includes radiosondes launched using weather balloons, a variety of satellites, and aircraft. Satellites can monitor temperatures in the upper atmosphere but are not commonly used to measure temperature change at the surface. Ocean temperatures at different depths are measured to add to global surface temperature datasets. This data is also used to calculate the <a href="/facts/Ocean_heat_content/RDwuuFnm">ocean heat content</a>.
Through 1940, the average annual temperature increased, but was relatively stable between 1940 and 1975. Since 1975, it has increased by roughly 0.15 °C to 0.20 °C per decade, to at least 1.1 °C (1.9 °F) above 1880 levels. The current annual GMST is about 15 °C (59 °F), though monthly temperatures can vary almost 2 °C (4 °F) above or below this figure.
The global average and combined land and <a href="/facts/Sea_surface_temperature/D9bNcRxX">ocean surface temperature</a> show a warming of 1.09 °C (range: 0.95 to 1.20 °C) from 1850–1900 to 2011–2020, based on multiple independently produced datasets.: 5  The trend is faster since the 1970s than in any other 50-year period over at least the last 2000 years.: 8  Within that upward trend, some variability in temperatures happens because of <a href="/facts/Climate_variability_and_change/D3X6Ulbu">natural internal variability</a> (for example due to <a href="/facts/El_Ni%C3%B1o%E2%80%93Southern_Oscillation/FVgabDRn">El Niño–Southern Oscillation</a>).
The global temperature record shows the changes of the <a href="/facts/Temperature/QyGe4gmj">temperature</a> of the atmosphere and the oceans through various spans of time. There are numerous estimates of temperatures since the end of the <a href="/facts/Pleistocene/0ya9eUp5">Pleistocene</a> <a href="/facts/Glaciation/alIAm38r">glaciation</a>, particularly during the current <a href="/facts/Holocene/sppPgwW5">Holocene</a> epoch. Some temperature information is available through geologic evidence, going back millions of years. More recently, information from <a href="/facts/Ice_core/QnzraAoN">ice cores</a> covers the period from 800,000 years ago until now. <a href="/facts/Tree_Rings/bXK8Km2M">Tree rings</a> and measurements from ice cores can give evidence about the global temperature from 1,000-2,000 years before the present until now.

Global surface temperature open-in-new

Global surface temperature