Note: After writing a draft of this entry, I went to the Real Climate website (I should have thought of it first; thanks Fraser for the tip!) and they already have a post up on this topic. It looks like we essentially agree on this issue. I may be an astronomer, but I know data analysis! Anyway see links at Real Climate for more on this story. I have edited my entry a bot, but it's essentially what I drafted up originally.
Via Gia's blog, I have learned that some scientists are claiming that they have found that the warming trend in the last half of the 20th Century is wrong. If so, this is a major revision of climate change science. However, I don't think this is correct. Basically, the claim is that the numbers published by NASA scientist James Hansen had an error in them. When this is corrected, the warming trend in the last part of the 20th century disappears. But let's look closer at the numbers. The table below is from the Watt's Up With That blog, which discusses these claims. The first table lists the 10 hottest years on record, ordered using the new data. The columns are the year, the deviation from average temperature done the old way, and the deviation done the new way. Top 10 GISS U.S. Temperature deviation (deg C) in New Order 8/7/2007
Interestingly, the hottest year on record before was 1998 (1.24 degrees Celsius above average), but with the new data, it's now second to 1934. That's interesting! But hang on a sec. The difference is pretty small. 1998 went down by 0.01 degrees, and 1934 went up by 0.02. I would call that a wash... except that the error bars are not published where I could find them. Is an 0.01 change significant? What if the measurements are only good to 0.1 degrees? Then 1934 and 1998 are in a statistical dead heat (haha). Posting the numbers like this doesn't actually tell you what you need to know. Worse, some misleading claims have been made about them. For example, the Daily Tech site says:
YearOldNew
