Alan K. Henderson's Weblog


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Friday, August 10, 2007

NASA Revises US Warming Data

Coyote Blog has the story, and implores the reader to remember these issues (emphasis in original):

  • This is not the end but the beginning of the total reexamination that needs to occur of the USHCN and GISS data bases.  The poor correction for site location and urbanization are still huge issues that bias recent numbers upwards.  The GISS also has issues with how it aggregates multiple stations, apparently averaging known good stations with bad stations a process that by no means eliminates biases.  As a first step, we must demand that NOAA and GISS release their methodology and computer algorithms to the general public for detailed scrutiny by other scientists.

  • The GISS today makes it clear that these adjustments only affect US data and do not change any of their conclusions about worldwide data.  But consider this:  For all of its faults, the US has the most robust historical climate network in the world.  If we have these problems, what would we find in the data from, say, China?  And the US and parts of Europe are the only major parts of the world that actually have 100 years of data at rural locations.  No one was measuring temperature reliably in rural China or Paraguay or the Congo in 1900.  That means much of the world is relying on urban temperature measurement points that have substantial biases from urban heat.

  • All of these necessary revisions to surface temperatures will likely not make warming trends go away completely.  What it may do is bring the warming down to match the much lower satellite measured warming numbers we have, and will make current warming look more like past natural warming trends (e.g. early in this century) rather than a catastrophe created by man.  In my global warming book, I argue that future man-made warming probably will exist, but will be more like a half to one degree over the coming decades than the media-hyped numbers that are ten times higher.
I am curious about one thing: assuming the data are correct (a claim which Coyote Blog's second point challenges), why are the warming trends far less acute in the US than in the world at large? Contrast the global and contiguous 48 US states temperature anomaly graphs.

Whoa, hold on a sec. NASA's global chart says the global temperature anomaly peaked in 2004. But the Hadley Centre of the UK Meteorological Office (the source for Wikipedia's chart) says the global anomaly peaked in 1998, the same year it peaked in North America. Who's right?

Update: I was looking through some old global warming posts and I discovered that Wikipedia is now using the GISS data. American Thinker has a chart based on the Hadley data - the global anomaly clearly peaks in 1998.


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