Tuesday, March 02, 2010

Global Warming and Science

The following citation is an interesting breakdown of the issues surrounding global temperatures over the last sixty or so years. It identifies five different issues with the 2007 IPCC claim which attributes most of the rise of 0.7 ° C over that period to human GHG.

This article identifies five different issues with the Hadley ("Climategate") data which is the basis for the IPCC claim. These five issues break down into two different types: those which modify the original 0.7 ° C itself and those which attribute a different cause. Of those which suggest different causes, some are not anthropogenic, but one is (soot).

So let's correct the original number to 0.47 ° C by eliminating the sea surface temperature errors and the non-climatic signal change ("urbanization"). We then identify four possible causes contributing to this change. Two are anthropogenic and two are not. Those causes we are not responsible for are Stratospheric water vapour and the Sun. Stratospheric water vapour contributes about 0.06 ° C. The Sun's contribution is more problematic.

We don't actually know what, if anything, the sun contributes to our climate variations. The seasons themselves seems to indicate a large role--less sunlight equals colder temperatures. But what about longer-term changes in climate? The scientist cited comes up with different hypotheses that range from no contribution to 65% of the observed warming over the last sixty years. He then cited plumps for 33% for no reason cited. Yet the graph only drops 0.1 ° C. So something is being done with these successive graphs that I'm not understanding.

Of the two anthropogenic causes Black Carbon (soot) contributes 0.1 ° C or about twenty percent of the total. The remainder includes GHG and any other causes as yet unidentified. This apparently amounts to about 0.2 ° C or about 40% of the total. In other words, we seem to be contributing more than twenty percent to current warming, but possibly less than sixty percent. That still seems pretty serious to me, so I'm at a loss to explain the articles conclusion which reduces GHG's contribution to less than a third (which it may, in fact, be) by merging all the various issues indiscriminately.

Most of the Observed Warming since the Mid-20th Century Likely Not from Human GHG Emissions?:

A few weeks ago, over at the blog MasterResource.org, WCR’s Chip Knappenberger took a look at just how confident one should be regarding the amount of warming that anthropogenic greenhouse gas (GHG) emissions have caused since the mid-20th century.
The IPCC claims that it is “very likely” that “most” of the warming since then has been [...]

Read the whole thing.

(Via World Climate Report.)

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