ThinkProgress: A major new study finds that scientists may have hugely underestimated the extent of global warming because temperature readings from southern hemisphere seas were inaccurate. In short, as New Scientist puts it, its worse than we thought. This study is the umpteenth nail in the coffin to the notion we can weaken or replace the 2°C limit for global warming as a basis for climate change policy, which was the central argument of a Nature Comment last week, titled, Ditch the 2°C warming goal....