Chapter 7 of 10All chapters
Chapter 7 of 10
A changing climate
What is measured.
The observations
Global average surface temperature has risen by roughly 1.2 degrees Celsius since the late nineteenth century. Ocean heat content, sea level and ice loss all point the same way.
- Multiple independent datasets and methods agree on the trend.
- Carbon dioxide has risen from about 280 to over 420 parts per million.
Attribution
The isotopic signature of the added carbon matches fossil sources, and the pattern of warming, with a cooling upper atmosphere, matches greenhouse forcing rather than a brighter Sun.