Updated IPCC Forecasts vs. Observations

January 26th, 2008

Posted by: Roger Pielke, Jr.

IPCC Verification w-RSS correction.png

Carl Mears from Remote Sensing Systems, Inc. was kind enough to email me to point out that the RSS data that I had shared with our readers a few weeks ago contained an error that RSS has since corrected. The summary figure above is re-plotted with the corrected data (RSS is the red curve). At the time I wrote:

Something fishy is going on. The IPCC and CCSP recently argued that the surface and satellite records are reconciled. This might be the case from the standpoint of long-term linear trends. But the data here suggest that there is some work left to do. The UAH and NASA curves are remarkably consistent. But RSS dramatically contradicts both. UKMET shows 2007 as the coolest year since 2001, whereas NASA has 2007 as the second warmest. In particular estimates for 2007 seem to diverge in unique ways. It’d be nice to see the scientific community explain all of this.

For those interested in the specifics, Carl explained in his email:

The error was simple — I made a small change in the code ~ 1 year ago that resulted in a ~0.1K decrease in the absolute value of AMSU TLTs, but neglected to reprocess data from 1998-2006, instead only using it for the new (Jan 2007 onward) data. Since the AMSU TLTs
are forced to match the MSU TLTs (on average) during the overlap period, this resulted in an apparent drop in TLT for 2007. Reprocessing the earlier AMSU data, thus lowering AMSU TLT by 0.1
from 1998-2006, resulted in small changes in the parameters that are added to the AMSU temperatures to make them match MSU temperatures, and thus the 2007 data is increased by ~0.1K. My colleagues at UAH (Christy and Spencer) were both very helpful in diagnosing the problem.

It is important to note that the RSS correction does not alter my earlier analysis of the IPCC predictions (made in 1990, 1995, 2001, 2007) and various observations. Thanks again to Carl for alerting me to the error and giving me a chance to update the figures with the new information!

One Response to “Updated IPCC Forecasts vs. Observations”

  1. Harry Haymuss Says:

    Did you get the HADCRUT3 update? December 2007 had the coldest anomaly this century…