4 sources say: “globally cooler” in the past 12 months

January 2008 was an exceptional month for our planet, with a significant cooling, especially since January 2007 started out well above normal.

January 2008 capped a 12 month period of global temperature drops on all of the major well respected indicators. I have reported in the past two weeks that HadCRUT, RSS, UAH, and GISS global temperature sets all show sharp drops in the last year.

Also see the recent post on what the last 10 years looks like with the same four metrics – 3 of four show a flat trendline.

Here are the 4 major temperature metrics compared top to bottom, with the most recently released at the top:

UK’s Hadley Climate Research Unit Temperature anomaly (HadCRUT) Dr. Phil Jones:

Reference: above data is HadCRUT3 column 2 which can be found here
description of the HadCRUT3 data file columns is here

NASA Goddard Institute for Space Studies (GISS) Dr. James Hansen:

Reference: GISS dataset temperature index data

University of Alabama, Huntsville (UAH) Dr. John Christy:
Reference: UAH lower troposphere data

Remote Sensing Systems of Santa Rosa, CA (RSS):

Reference: RSS data here (RSS Data Version 3.1)

The purpose of this summary is to make it easy for everyone to compare the last 4 postings I’ve made on this subject.

I realize that not all the graphs are of the same scale, so my next task will be to run a combined graphic of all the data-sets on identical amplitude and time scales to show the agreements or differences such a graph would illustrate.

UPDATE: that comparison has been done here

Here is a quick comparison and average of ∆T for all metrics shown above:

For all four metrics the global average ∆T for January 2007 to January 2008 is: – 0.6405°C

This represents an average between the two lower troposphere satellite metrics (RSS and UAH) and the two land-ocean metrics (GISS and HadCRUT). While some may argue that they are not compatible data-sets, since they are derived by different methods (Satellite -Microwave Sounder Unit and direct surface temperature measurements) I would argue that the average of these four metrics is a measure of temperature, nearest where we live, the surface and near surface atmosphere.

UPDATE AND CAVEAT:

The website DailyTech has an article citing this blog entry as a reference, and their story got picked up by the Drudge report, resulting in a wide distribution. In the DailyTech article there is a paragraph:

“Anthony Watts compiled the results of all the sources. The total amount of cooling ranges from 0.65C up to 0.75C — a value large enough to erase nearly all the global warming recorded over the past 100 years. All in one year time. For all sources, it’s the single fastest temperature change ever recorded, either up or down.”

I wish to state for the record, that this statement is not mine: “–a value large enough to erase nearly all the global warming recorded over the past 100 years”

There has been no “erasure”. This is an anomaly with a large magnitude, and it coincides with other anecdotal weather evidence. It is curious, it is unusual, it is large, it is unexpected, but it does not “erase” anything. I suggested a correction to DailyTech and they have graciously complied.

UPDATE #2 see this post from Dr. John R. Christy on the issue.

UPDATE #3 see the post on what the last 10 years looks like with the same four metrics – 3 of four show a flat trendline.