Over at WUWT the deniers are taking a deep breath and preparing themselves for a hotter year this year. Werner Brozek (Edited By Just The Facts) has a new article (archived here), warning WUWT-ers that if temperatures keep going along the lines of April, then this year could be up there with 2010 and 2005 as the hottest year on record - and this is before any El Niño has been declared.
It's a bit early to make any predictions. GISTemp for the first four months is trailing 2010 but has crept above 2005, as you can see from the chart below.
|Data Source: NASA GISTemp|
Werner's also observed what I noticed, that there have been a lot of new adjustments to GISTemp recently. Not just for the past twelve months but going back further in time. I haven't seen any explanation on the GISTemp website for the most recent changes yet. I expect it will come as they are usually quite diligent in giving explanations.
Some people are querying the changes as a conspiracy to make earlier records colder so that later records look warmer. However more recent records have been adjusted downwards and older records adjusted upwards. That will puzzle WUWT-ers no end. (If they follow the recursive fury pattern I expect they'll try to amend the conspiracy theory while keeping it to "nefarious intent" but it's hard to see how.)
Below is a chart showing the adjustments over time as the net adjustment for the year. I've compared the latest GISTemp data with that from the end of 2013, subtracting the older anomalies from the newer. That is, a positive value means that the latest GISTemp data has been adjusted up and a negative value means the data has been revised down.
You can see that most of the upward adjustments have been in earlier years, while in later years the anomalies have been adjusted down. All but a few this decade have a net effect of only 0.01 degrees in any year.
|Data Source: NASA GISTemp|
As for this year, April was a hot month and it looks to me that May has been a tad warm in some parts of the world. If El Niño emerges then that will only add to the trend.
From the WUWT comments
Scott Basinger gets it topsy turvy and says:
May 25, 2014 at 6:15 pm
Adjust the past down, adjust the present up. Look, a trend!
May 25, 2014 at 6:26 pm
Latitude says: May 25, 2014 at 6:08 pm
I can understand that there could possibly be good reasons why things could be adjusted from a hundred years ago, but why would 2010 be adjusted in the last 4 months? And why would the all time record month of January 2007 go down from 0.94 to 0.92 over the last 4 months?
Late arrival of data can lead to adjustments. But this looks to be more than that. Either GISTemp has had a big spring clean or the algorithm has been modified. Maybe I'll ask Gavin Schmidt.
Bill H says:
May 25, 2014 at 6:44 pmThe more observations the better the precision can be. That's statistics.
One hundredth of a degree C… What instrument is so carefully calibrated and placed around the world so quickly that we are talking this small a change?