Globally Averaged Temperature Anomaly
A monthly measure of how much the earth is warming or cooling that is calculated using:
(1) GHCN for land surface temperatures.
(2) the ERSST analysis for sea surface temperatures.
1. The monthly analysis begins January 1854, but due to very sparse data, no global averages are computed before 1880. With more observations after 1880, the signal is stronger and more consistent over time.
2. For a complete explanation of how it is calculated, go to NOAA National Climatic Data Center. For the actual monthly climate info, click here.
3. Usage Example (from Richard Lindzen): "Given that the evidence … suggests that anthropogenic warming has been greatly exaggerated, so too is the basis for alarm. However, the case for alarm would still be weak even if anthropogenic global warming were significant. Polar bears, arctic summer sea ice, regional droughts and floods, coral bleaching, hurricanes, alpine glaciers, malaria, etc., all depend not on GATA but on a huge number of regional variables including temperature, humidity, cloud cover, precipitation, and direction and magnitude of wind and the state of the ocean."