Why The CRU (and GISS and NCDC) Global Surface Temperature Anomalies Are So Important To Policy

Yesterday, I posted on the two questions below and gave the answers for each question

Do The CRU E-mails Change The IPCC Conclusions On The late 19^th, 20th and early 21st Century Surface Temperature Trends?  

NO

Does The CRU Data (and thus the IPCC) Overstate The Magnitude Of Global Warming?

YES

Today at the Copenhagen meeting, the following is one of the news reports
Vulnerable nations at Copenhagen summit reject 2C target – Alliance of Small Island States say any deal that allows temperatures to rise by more than 1.5C is ‘not negotiable’

This news article includes the text

“More than half the world’s countries say they are determined not to sign up to any deal that allows temperatures to rise by more than 1.5C – as opposed to 2C, which the major economies would prefer.

But any agreement to reach that target would require massive and rapid cuts in greenhouse gas emissions combined with removal of CO2 in the atmosphere. An extra 0.5C drop in temperatures would require vastly deeper cuts in carbon dioxide and up to $10.5 trillion (£6.5tr) extra in energy-related investment by 2030, according to the International Energy Agency.”

This is why the second question and its answer is so important. It is clear in the peer reviewed literature (e.g. see and see) that the IPCC (and COP15)  is using a data set (which the CRU, NASA and NCDC analyses use) that has a significant warm bias when used as the metric for global warming (e.g. see), as well as an erroneous attribution of the majority of the warming to human added carbon dioxide (e.g. see and see);

• There are systematic (i.e. non-random) effects introduced into the surface air temperature from non-climatic site exposures, as well as statistical uncertainty associated with the time of observation bias and change of instrumentation, and of the degree of dependence imposed when “homogenizing” nearby observing sites.
• In terms of attribution, there are other effects besides changes in radiative forcing that alters the long-term surface temperature, of which land use change, concurrent trends in surface air water vapor content, and aerosols have been shown exert major influences.

This focus on a global average temperature threshold (of +1.5C or 2C), as reported in the news article, and the assumption that reaching this threshold is primarily a function of the emissions of CO2 is inaccurate. The participants at COP15 have been mislead (and the leaked CRU e-mails illustrate why, as alternative viewpoints such as I have expressed in this e-mail have been squelched) .