McClatchy Newspapers: A new scientific study adds evidence that temperatures in the Northern Hemisphere fluctuated a bit over time, but that the sharp increase during the past few decades is bigger than anything in at least 1,300 years. The report was published Tuesday in the Proceedings of the National Academy of Sciences. Its conclusion is that temperature increased and decreased a little over the centuries, but the fluctuations were small enough that the line was roughly flat, like the shaft of a …