Last Updated:
February 28, 2007

GCRIO Program Overview

Library 
Our extensive collection of documents.

Privacy Policy

Archives of the
Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999

FROM VOLUME 10, NUMBER 4, APRIL 1997

NEWS...
SATELLITE TEMPERATURE TREND

Item #d97apr44

Satellite measurements of global temperature available since 1979 show a slight cooling trend, while the record based on thermometers at ground level indicate warming over the same period. This apparent discrepancy has fueled debate over the existence of global warming in recent decades. In the September 1996 issue of the Journal of Climate, James Hurrell and Kevin Trenberth discussed how the two records measure related but different physical properties, yielding different perspectives on the same events. (See PROF. PUBS./OF GEN. INTEREST, Feb. 1997.)

A new study by the same authors suggests that the satellite record contains downward jumps that are artifacts of the instruments used, resulting from the need to merge data collected by different satellites into a single record. The corrected record would show a slight warming, as do surface measurements. (See PROF. PUBS./OF GEN. INTEREST, this Global Climate Change Digest issue--Apr. 1997.)

This argument is rejected by John Christy, the scientist who maintains the satellite record. He says the satellite temperatures compare well with those measured by balloons in the middle atmosphere, and that the jumps in the data found by Hurrell and Trenberth reflect real changes in the atmosphere. His comments and those of other scientists are discussed in Science News (p. 156, Mar. 15, 1997). See also New Scientist (p. 18, Mar. 15), and Global Environ. Change Rep. (p. 4, Mar. 14).