‘Is the climate warming?’ is the first question the Royal Society’s answers in its short guide to climate science. The series aims to create well informed conversations around the issues of climate change and its impacts.
Is the climate warming?
Yes. Earth’s average surface air temperature has increased by about 0.8C since 1900, with much of this increase taking place since the mid-1970s. 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 incontrovertible evidence of planetary-scale warming.
The clearest evidence for surface warming comes from widespread thermometer records. In some places, these records 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 1983 to 2012 was probably the warmest 30-year period in more than 800 years.
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. These measurements are made with a variety of monitoring systems, which gives added confidence in the reality that Earth’s climate is warming.
For more information from the Royal Society’s guide click here.
Photo: Liam Quinn via Flickr