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Politics : The Environmentalist Thread -- Ignore unavailable to you. Want to Upgrade?

To: maceng2 who wrote (19758)	1/22/2008 1:59:34 PM
From: Alastair McIntosh	Read Replies (1) \| Respond to of 36921

Perhaps you would be interested in the actual peer reviewed paper by McKitrick and Michaels. You seem to have completely missed the point of their paper. uoguelph.ca Here is the abstract: Local land surface modification and variations in data quality affect temperature trends in surface-measured data. Such effects are considered extraneous for the purpose of measuring climate change, and providers of climate data must develop adjustments to filter them out. If done correctly, temperature trends in climate data should be uncorrelated with socioeconomic variables that determine these extraneous factors. This hypothesis can be tested, which is the main aim of this paper. Using a new data base for all available land-based grid cells around the world we test the null hypothesis that the spatial pattern of temperature trends in a widely-used gridded climate data set is independent of socioeconomic determinants of surface processes and data inhomogeneities. The hypothesis is strongly rejected (P=7.1E-14), indicating that extraneous (nonclimatic) signals contaminate gridded climate data. The patterns of contamination are detectable in both rich and poor countries, and are relatively stronger in countries where real income is growing. We apply a battery of model specification tests to rule out spurious correlations and endogeneity bias. We conclude that the data contamination likely leads to an overstatement of actual trends over land. Using the regression model to filter the extraneous, nonclimatic effects reduces the estimated 1980-2002 global average temperature trend over land by about half. The conclusion states: “These results are also consistent with previous findings showing that nonclimatic factors, such as those related to land use change and variations in data quality, likely add up to a net warming bias in climate data, suggesting an overstatement of the rate of global warming over land. They also provide support for attribution of some observed climate changes in recent decades to land surface modifications, rather than greenhouse gas emissions, a factor not typically evaluated in studies that attempt to attribute the causes of recent global warming.” What McKitrick and Michaels did not do: 1. Exclude data based on socioeconomic variables 2. Suggest that socioeconomic variables reflected on the skill of staff handling meteorological data 3. Assign a higher weighting to more developed countries. You state: So guess what, you diminish the effect on averages of the hottest countries, and global warming average change goes down. How surprising. This was not the conclusion of the paper. In fact, the paper shows that the overstatement of temperature trends is greater in areas of higher GDP, population density, income and other local factors. The IPCC state that their adjustment models remove any artificial warm bias in the climate records. However this paper shows as much as one half of the observed temperature trend since 1980 is the result of factors other than greenhouse gases. To date, there has been no peer reviewed rebuttal of this paper.

To: maceng2 who wrote (19758)	1/22/2008 4:09:25 PM
From: TimF	Respond to of 36921

Its far from certain that "American and other "advanced nations" data is as good or as bad as any other data." And even if it is true than it doesn't necessarily mean the other data is all that good. So guess what, you diminish the effect on averages of the hottest countries, and global warming average change goes down. How surprising. Hotter countries don't necessarily have more warming. Sure they ended up warmer but they also started out warmer. Let the normal process used by scientists be used to check the validity of the measurements taken. That much I can agree with. There is no valid science textbook I know of that requests the investigator to check the bank balance of the person who made a measurement, and to statistically weight it's validity based on an observers bank balance. Your beating up on a straw man. No one here, or quoted here, made any claim that even vaguely resembled that one.