Tuesday, August 21, 2007

Today's editorial: Cool it, hotheads
Some alarming global-warming data reconsidered.

An Orange County Register Editorial

While Americans were being stampeded at great cost and inconvenience into combating the presumed horrors of manmade global warming – be it in Newsweek or by the California Attorney General's Office – some news largely went unnoticed last week.

Instead of 1998 being the "hottest year" since 1880 in the continental United States, as some global warming alarmists claimed, it turns out that 1934 was. Instead of nine of the 10 hottest years since 1880 occurring after 1995, it turns out that four of the hottest years were in the 1930s, and the third-hottest was 1921. Only three have been in the past decade.

This is significant not merely because it means things aren't necessarily getting warmer. It also means manmade CO2, presumably global warming's cause, may not be. That's because the 15 hottest years now are spread over seven decades, more than half occurring before CO2's sharp rise in the atmosphere. Of course, drawing connections between climate change and temperatures, whether daily or annual, always has been problematic. Weather and climate are different things, but they often have been commingled in the heat of the debate.

This shamefully underreported temperature development came to light when a private blogger and mathematician, Canadian Stephen McIntyre, discovered a serious math error made by NASA, which monitors U.S. temperatures. NASA's sheepish response was to quietly acknowledge the error, briefly note the correction on a Web site and thank McIntyre for his trouble.

Prominent global warming zealot James Hansen of NASA's Goddard Institute for Space Studies feebly tried to downplay the corrected numbers, saying U.S. temperature readings account for only 2 percent of the Earth's land surface. But as McIntyre noted, the significance of what he calls the "Hansen error" extends beyond U.S. temperature readings. While U.S. temperature measuring stations are of questionable reliability, nevertheless they are far more sophisticated and therefore likelier to be more accurate gauges than foreign stations.

The assumptions of global warming theorists increasingly seem built on sand, not bedrock. You may say, "Doesn't an overwhelming majority of scientists believe man is behind global warming?" Not quite.

"It's like an urban legend," former NASA scientist Roy Spencer of the University of Alabama recently told columnist Debra J. Saunders. In 2003 two German environmental scientists asked 530 climate scientists from 27 countries if global warming was manmade. Fifty-six percent said yes; 30 percent said no, Saunders reported.

Some scientists flatly say there's been no global temperature increase since that supposedly so-hot year of 1998. Others say solar activity causes warming. Still others predict the Earth is on the brink of worldwide cooling. We don't presume to have the answers. But we're highly suspicious of those who unequivocally claim global warming is dangerously escalating, man is its principal cause and it's necessarily devastating.

Some things are certain. Global warming alarmists won't be discouraged easily. Neither will those seizing on the dire warming projections to expand their control or reap profits from Draconian economic schemes like greenhouse gas cap-and-trade plans, essentially licenses to buy and sell make-believe "rights" to pollute.

Contrary to alarmists' claims, global warming science is far from settled. As politicians and opportunists try to stampede us, we must ask, "What's the rush?"

Instead of nine of the 10 hottest years since 1880 occurring after 1995, it turns out that four of the hottest years were in the 1930s, and the third-hottest was 1921. Only three have been in the past decade.

What I can't wait for is when one of the AGW freaks calls James Hansen a Global Warming Denier.

1934 and all that
Filed under: Instrumental Record Climate Science — gavin @ 5:33 PM

Another week, another ado over nothing.

Last Saturday, Steve McIntyre wrote an email to NASA GISS pointing out that for some North American stations in the GISTEMP analysis, there was an odd jump in going from 1999 to 2000. On Monday, the people who work on the temperature analysis (not me), looked into it and found that this coincided with the switch between two sources of US temperature data. There had been a faulty assumption that these two sources matched, but that turned out not to be the case. There were in fact a number of small offsets (of both sign) between the same stations in the two different data sets. The obvious fix was to make an adjustment based on a period of overlap so that these offsets disappear.

This was duly done by Tuesday, an email thanking McIntyre was sent and the data analysis (which had been due in any case for the processing of the July numbers) was updated accordingly along with an acknowledgment to McIntyre and update of the methodology.

There were some very minor knock on effects in earlier years due to the GISTEMP adjustments for rural vs. urban trends. In the global or hemispheric mean, the differences were imperceptible (since the US is only a small fraction of the global area).

There were however some very minor re-arrangements in the various rankings (see data). Specifically, where 1998 (1.24 ºC anomaly compared to 1951-1980) had previously just beaten out 1934 (1.23 ºC) for the top US year, it now just misses: 1934 1.25ºC vs. 1998 1.23ºC. None of these differences are statistically significant. Indeed in the 2001 paper describing the GISTEMP methodology (which was prior to this particularly error being introduced), it says:

The U.S. annual (January-December) mean temperature is slightly warmer in 1934 than in 1998 in the GISS analysis (Plate 6). This contrasts with the USHCN data, which has 1998 as the warmest year in the century. In both cases the difference between 1934 and 1998 mean temperatures is a few hundredths of a degree. The main reason that 1998 is relatively cooler in the GISS analysis is its larger adjustment for urban warming. In comparing temperatures of years separated by 60 or 70 years the uncertainties in various adjustments (urban warming, station history adjustments, etc.) lead to an uncertainty of at least 0.1°C. Thus it is not possible to declare a record U.S. temperature with confidence until a result is obtained that exceeds the temperature of 1934 by more than 0.1°C.

More importantly for climate purposes, the longer term US averages have not changed rank. 2002-2006 (at 0.66 ºC) is still warmer than 1930-1934 (0.63 ºC - the largest value in the early part of the century) (though both are below 1998-2002 at 0.79 ºC). (The previous version - up to 2005 - can be seen here).

In the global mean, 2005 remains the warmest (as in the NCDC analysis). CRU has 1998 as the warmest year but there are differences in methodology, particularly concerning the Arctic (extrapolated in GISTEMP, not included in CRU) which is a big part of recent global warmth. No recent IPCC statements or conclusions are affected in the slightest.

Sum total of this change? A couple of hundredths of degrees in the US rankings and no change in anything that could be considered climatically important (specifically long term trends).

However, there is clearly a latent and deeply felt wish in some sectors for the whole problem of global warming to be reduced to a statistical quirk or a mistake. This led to some truly death-defying leaping to conclusions when this issue hit the blogosphere. One of the worst examples (but there are others) was the 'Opinionator' at the New York Times (oh dear). He managed to confuse the global means with the continental US numbers, he made up a story about McIntyre having 'always puzzled about some gaps' (what?) , declared the the error had 'played havoc' with the numbers, and quoted another blogger saying that the 'astounding' numbers had been 'silently released'. None of these statements are true. Among other incorrect stories going around are that the mistake was due to a Y2K bug or that this had something to do with photographing weather stations. Again, simply false.

But hey, maybe the Arctic will get the memo.

So it turns out that the denialists are screeching about nothing...again.

So it turns out that the denialists are screeching about nothing...again.