Wednesday, February 06, 2008

For those who want to see the science

There are those who will persist in subscribing to the theory of AGW even when the data exist to refute it. Others merely want to see some scientific studies that clearly counter the AGW claims with alternate data and not just analysis that suggests flaws and weaknesses in the argument.

For those who want to see a study that clearly refutes the claims of global warming, this study from Sweden to appear in the refereed journal, Climate Dynamics, will certainly fit the bill. The study finds confirms that:
  • the late-twentieth century is not exceptionally warm
  • the Medieval Warm Period is clearly evidenced: indeed, it was much warmer than previously recognized, and
  • the temperature reconstruction shows a trend of -0.3C over the past 1,500 years.
What the Swedish study shows is that temperatures have a slight cooling trend for the past 1,500 years. As illustrated in the graphs below, despite the recent warming of the last 200 years, present temperatures are neither unprecedented nor alarming, as past temperatures in AD 750, 1000, 1400 and 1750 were all as warm or warmer than today.

So what we have is a study from Scandinavia and another from California both confirming the Medieval Warm Period, evidence that the MWP may have even been warmer than previously supposed, additional support for a natural cycling of temperatures, and no evidence of any elevated carbon dioxide connected to any changes.

O.K., so what else is necessary to refute the theory if it is all about the science?

  • if you have a proxy with no correlation with temperature and do a reconstruction and then add the instrumental record at the end, you get a hockey stick, because the recon will just be white noise (or red noise) with a mean of 0. Craig Loehle