Global Temperature Report — October 2009

The only October in the past 31 that was warmer in the tropics than last month was October 1987, when the average temperature in the tropics was 0.53 C (about 0.95 degrees Fahrenheit) warmer than seasonal norms. The October 2009 average temperature in the tropics was 0.33 C (about 0.6 degree Fahrenheit) warmer than seasonal norms.

At the same time, the average temperature over the 48 contiguous states was 1.45 C (about 2.61 degrees Fahrenheit) cooler than seasonal norms for October. The coldest October in the past 31 was in 2002, when average temperatures dropped 1.48 C (about 2.66 degrees Fahrenheit) below normal. By comparison, the next coldest October was in 2006, when temperatures in the continental U.S. were only 0.8 C cooler than normal.

Global climate trend since Nov. 16, 1978: +0.13 C per decade

October temperatures (preliminary)

Global composite temp.: +0.28 C (about 0.50 degrees Fahrenheit) above 20-year average for October.

Northern Hemisphere: +0.27 C (about 0.49 degrees Fahrenheit) above 20-year average for October.

Southern Hemisphere: +0.30 C (about 0.54 degrees Fahrenheit) above 20-year average for September.

September temperatures (revised):

Global Composite: +0.42 C above 20-year average

Northern Hemisphere: +0.55 C above 20-year average

Southern Hemisphere: +0.29 C above 20-year average

(All temperature variations are based on a 20-year average (1979-1998) for the month reported.)

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.

Dr. John Christy, UAH, (256) 961-7763
john.christy@nsstc.uah.edu
Dr. Roy Spencer, UAH, (256) 961-7960
roy.spencer@nsstc.uah.edu