A funny thing happened on the way to determining how hot 2012 has been on a global basis: temperatures changed in 1880. We've been hearing that 2012 has been the "hottest on record." I had written earlier that those claims were based on the contiguous United States only, or 1.5% of the earth's surface. The "global temperature" in 2012 through June was only the 10th hottest on record. In fact, every single month of 1998 was warmer than the corresponding month of 2012. I thought I'd update that analysis to include July's and August's temperatures. To my surprise, NASA's entire temperature record, going back to January 1880, changed between NASA's June update and its August update. I could not just add two more numbers to my spreadsheet. The entire spreadsheet needed to be updated. I knew NASA would occasionally update its estimates, even its historical estimates. I found that unsettling when I first heard about it. But I thought such re-estimates were rare, and transparent. There is...(Read Full Post)