Every month University of Alabama in Huntsville climatologists John Christy and Roy Spencer report the latest global temperature trends from satellite data. Below are the newest data updated through April, 2012.
Global climate trend since Nov. 16, 1978: +0.13 C per decade
April temperatures (preliminary)
Global composite temp.: +0.30 C (about 0.54 degrees Fahrenheit) above 30-year average for April.
Northern Hemisphere: +0.41 C (about 0.74 degrees Fahrenheit) above 30-year average for April.
Southern Hemisphere: +0.18 C (about 0.32 degrees Fahrenheit) above 30-year average for April.
Tropics: -0.12 C (about 0.22 degrees Fahrenheit) below 30-year average for April.
Notes on data release:
Spring brought somewhat more seasonal temperatures to the continental U.S., although it was still warmer than seasonal norms in April, according to Dr. John Christy, a professor of atmospheric science and director of the Earth System Science Center at The University of Alabama in Huntsville. Temperatures over the contiguous 48 states averaged 1.49 C (about 2.7 degrees Fahrenheit) warmer than seasonal norms in April, making it the fifth warmest April in the 33-year satellite climate record. That was cooler than the record-setting 2.82 C (almost 5.1 degrees Fahrenheit) anomaly in March.
April 2012 was the fourth warmest April in the temperature record both globally and in the Northern Hemisphere. It was the warmest April in 33 years for the Northern Extra Tropics — everything from 20 degrees North all the way to the North Pole. Average temperatures there for the month were 0.73 C (1.3 degrees F) warmer than seasonal norms.
Go here to see the full satellite dataset.