Thursday, April 02, 2009

It's Not All About CO2

An important study, published last December, has received little attention. Entitled Reanalysis of Historical Climate Data for Key Atmospheric Features authored by Randall Dole, Martin Hoerling, and Siegfried Schubert and others of the National Oceanic and Atmospheric Administration (NOAA), the report is one of the first from NOAA to break with the alarmist party line and look at a more complex understanding of climate patterns. Its conclusions moderate the claims of Hansen and others with respect to anthropomorphic global warming.

The study, which stresses that we don't understand climate as well as we like to think, because scientists only have good data from about 1948 onward, found:

  • The 56-year trend of annual surface temperature showed a rise of 0.9C, plus or minus one-tenth of a degree.
  • The greatest warming -- up two degrees -- has taken place across Alberta, Saskatchewan, Yukon and Alaska. Quebec and Atlantic Canada stayed cool.
  • That East-West difference "is not what we would expect from the effect of greenhouse gases alone," Mr. Hoerling said. Greenhouses gases should have influenced both. However, NOAA believes Western Canada is receiving more warm air due to shifting patterns of the Pacific Ocean currents.
  • Variations within North America "are very likely influenced by variations in global sea surface temperatures through the effects of the latter on atmospheric circulation, especially during winter." The term "very likely" is defined as a chance of 90% or more.
  • It's "unlikely" that patterns of drought have changed due to global warming caused by human pollution. Rather, natural shifts in ocean currents are probably to blame. For instance, the current drought in Texas and the southwest are due to La Nina, a Pacific Ocean current that starts and stops periodically (such as El Nino), and cuts off the movement of moist air inland. Warmer temperatures from greenhouse gases, however, would worsen the basic drought.
  • Seven of the warmest 10 years since 1951 occurred in the decade from 1997 to 2006. The data in the study cover only to the end of 2007.
  • More than half of the warming averaged over all of North America is likely (more than 66 percent likelihood) the result of human activity.

The key to all of this is the move away from talk of “average global temperature” and the focus on regional differences and understanding their underlying cause. It is important for another reason too: it is the first time that NOAA has fully described ocean current impacts on regional climate.

What they need now to do is to look more critically at the greenhouse gas theory and the role of the sun and we may be getting nearer to an understanding of the dynamics of climate change, at least for North America.

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