Is the climate warming?
Yes. Earth’s average surface air temperature has increased by about 1.3°C since 1900. A wide range of other observations (such as reduced Arctic sea ice extent and increased ocean heat content) and indications from the natural world (such as poleward shifts of temperature-sensitive species of fish, mammals, insects, etc.) together provide conclusive evidence of planetary-scale warming.
The clearest evidence for surface warming comes from widespread thermometer records that, in some places, extend back to the late 19th century. Today, temperatures are monitored at many thousands of locations, over both the land and ocean surface. Indirect estimates of temperature change from such sources as tree rings and ice cores help to place recent temperature changes in the context of the past. In terms of the average surface temperature of Earth, these indirect estimates show that the most recent decade, 2015 – 2024, is the warmest decade in the instrumental record so far (since 1850). Over the last 50 years, global temperature has increased at a rate unprecedented in at least the last 2000 years.
Figure 1a: Annual and global mean surface temperature expressed as a difference from pre-industrial levels (defined as the period 1850 – 1900). Results are shown from six different analyses and combine near-surface air temperatures over land and sea surface temperatures over oceans.
A wide range of other observations provides a more comprehensive picture of warming throughout the climate system. For example, the lower atmosphere and the upper layers of the ocean have also warmed, snow and ice cover are decreasing in the Northern Hemisphere, the Greenland ice sheet is shrinking, and sea level is rising [Figure 1b]. These measurements are made with a variety of land-, ocean-, and space-based monitoring systems, which gives added confidence in the reality of global-scale warming of Earth’s climate.
Figure 1b. A large amount of observational evidence besides surface temperature records shows that Earth’s climate is changing. For example, additional evidence of a warming trend can be found in the loss of glacier mass, the increase in global sea level and the increases in ocean heat content. Source: IPCC AR6
Page last updated: July 2026
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