Global Temperature Report – July 2009

“Part of that is an artificial artifact of where we put the calendar boundaries,” Christy said. “Warmth from the new El Nino was not felt at all in June but really got going almost from the first day of July.”

At 0.41 C warmer than seasonal norms, July 2009 was second only to July 1998 (+0.51 C). July 1998 was on the back end of the most powerful El Nino Pacific Ocean warming event of the 20th century. That El Nino also caused the warmest monthly average temperature in the climate record: +0.77 in April 1998.

At 0.61 C warmer than seasonal norms, temperatures in the Southern Hemisphere in July tied May 1998 (during that big El Nino) as the second warmest month south of the equator. It was also the second warmest month on record in the Antarctic, where the average temperature was 3.11 C (about 5.60 degrees Fahrenheit) warmer than seasonal norms for the Antarctic winter. The warmest (compared to seasonal norms) was May 2002, when the continent's average temperature was 3.30 C warmer than normal.

Largest One-Month Change

Monthly Average Temperature

June “˜09 to July “˜09: +0.41 C

Dec. “˜06 to Jan. “˜07: +0.29 C

Dec. “˜04 to Jan. “˜05: +0.29 C

Sep. “˜84 to Oct. “˜84: +0.29 C

Feb. “˜99 to Mar. “˜99: – 0.28 C

Nov. “˜95 to Dec. “˜95: – 0.28 C

Aug. “˜84 to Sep. “˜84: – 0.28 C

As part of an ongoing joint project between The University of Alabama in Huntsville, NOAA and NASA, Christy and Dr. Roy Spencer, a principal research scientist in the ESSC, use data gathered by microwave sounding units on NOAA and NASA satellites to get accurate temperature readings for almost all regions of the Earth. This includes remote desert, ocean and rain forest areas for which reliable climate data are not otherwise available.

The satellite-based instruments measure the temperature of the atmosphere from the surface up to an altitude of about eight kilometers above sea level. Once the monthly temperature data is collected and processed, it is placed in a “public” computer file for immediate access by atmospheric scientists in the U.S. and abroad.

Neither Spencer nor Christy receives any research support or funding from oil, coal or industrial companies or organizations, or from any private or special interest groups. All of their climate research funding comes from state and federal grants or contracts.