My Bookmarks on Science & Technology, Climate Change, Astrobiology, Genetics, Evolution

September 12, 2010 – Original Source: Climate Progress, by Dr. Joseph Romm

August tied for hottest in UAH satellite record*

NASA reported it was the hottest January-July on record, along with a terrific analysis, “July 2010 — What Global Warming Looks Like,” which noted that 2010 is “likely” to be warmest year on record.

This month continues the trend of 2010 outpacing previous years, according to NASA:

It seems all but certain we will outpace 1998, which currently ties for fourth hottest year in the NASA dataset (though it is technically described by NASA folks as tied for the second hottest year with 2005 and 2007).

Outpacing 2005, the hottest year on record, will be closer.  In NASA’s surface-based dataset, we are unlikely to set the record monthly temperatures for the rest of this year; last month wasn’t close to the hottest August for NASA.  We  have entered a moderate La Niña, which NOAA saysis “expected to last at least through the Northern Hemisphere winter 2010-11.”

Interestingly, while the disinformers have been breathlessly touting the La Niña as sure to cool things down rapidly, global temperatures have held up quite well, even in the satellite datasets, which are typically sensitive to the El Niño Southern oscillation (ENSO).  The more trustworthyRSS data for August is not yet up, but even the UAH data for the lower troposphere shows August 2010 having almost an identical temperature to 1998, which was the hottest August on record.

And here is Roy Spencer’s much rejiggered UAH satellite data showing how warm it has been in early September — comparing 2010 lower trososphere temperatures (green) with average temps (blue) and record highs since 1979 (purple):

John Christy’s email caveat to me remains worth repeating — see After the hottest decade on record, it’s the hottest year on record, hottest week of all time in satellite record* and we may be at record low Arctic sea ice volume: “Please be aware that the values displayed have not been completely calibrated for the entire period (this has to do with some matching between the two different channel weighting functions through the annual cycle that is done in our normal processing at the end of the month but which is not done on the day-to-day chart you show.)  Improving the daily chart is work that is on-going.”  Well, until they fix it or take it down, people are still going to use it.  But as I said before, I no longer think that the UAH satellite dataset should be relied on for monthly comparisons.  Roy Spencer et al. are simply rejiggering and adjusting the data too much.  This might all be legit, but if NASA or NOAA tried something like this, Watts and McIntyre and Spencer would be trashing them daily.  And Spencer and Christy simply have not earned anybody’s trust about this sort of thing (see “Should you believe anything John Christy and Roy Spencer say?“).  So I await the RSS data.

NASA’s surface-based temperature record is most likely the most accurate, as I’ve noted many times (see Finally, the truth about the Hadley/CRU data: “The global temperature rise calculated by the Met Office’s HadCRUT record is at the lower end of likely warming”).

Finally, the record warmth that we are seeing this year is all the more powerful evidence of human-caused warming “because it occurs when the recent minimum of solar irradiance is having its maximum cooling effect,” as a recent must-read NASA paper notes:

It is just hard to stop the march of human caused global warming — other than by sharply reducing greenhouse gas emissions.

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