"In a new article just published in the Journal of Geophysical Research -- Atmospheres, a co-author and I have concluded that the manipulations for the steep post-1980 period are inadequate, and the above graph is an exaggeration. Along the way, I have also found that the United Nations agency promoting the global temperature graph has made false claims about the quality of its data.
...
Many long-term weather records come from in or near cities, which have gotten warmer as they grow. Many poor countries have sparse weather-station records and few resources to ensure data quality. Fewer than one-third of the weather stations operating in the 1970s remain in operation.
...
Our new paper presents a new, larger data set with a more complete set of socioeconomic indicators. We showed that the spatial pattern of warming trends is so tightly correlated with indicators of economic activity that the probability they are unrelated is less than one in 14 trillion. We applied a string of statistical tests to show that the correlation is not a fluke or the result of biased or inconsistent statistical modelling. We showed that the contamination patterns are largest in regions experiencing real economic growth. And we showed that the contamination patterns account for about half the surface warming measured over land since 1980.

In other words, we have confirmed, on new and stronger grounds, that the IPCC's global surface-temperature data is exaggerated, with a large warming bias. Claims about the amount of surface warming since 1980, and its attribution to anthropogenic greenhouse-gas emissions, should be reassessed using uncontaminated data. And governments that rely on the IPCC for advice should begin asking why it was allowed to suppress earlier evidence of this problem."
http://www.nationalpost.com/opinion/story.html?id=145245
Linked from http://www.climateaudit.org/

None of this is particularly surprising, but it's important that scientist such as Ross McKitrick do such work to show without any doubt that global warming is a Hoax. It may not make any political difference, because it's likely that global climate is not warming and may cool within a decade- and lack of any warming over next few years will probably do more than any scientific evidence, to convince most of the public who simply don't care enough about looking at the science. Or in other words fads have a certain shelf life, and Global warming already is way beyond it's shelf life. Now the government corruption involved with global warming will continue beyond the point in which it lacks any crediblity- because govt bureaucracy is does that kind of thing.
What important is the science is at least seen to work at some level so that science has enough respect, that future funding continues and that in matter in which the public needs depend on scientific knowledge, it has some credibility.