Readers of this blog will be familiar with the many problems of surface temperature measurement – the measurement points are geographically spotty, of uneven quality, and are subject to a number of biases, the greatest of which is probably the encroachment of man-made urban environments on the measurement locations. I have discussed these issues many places, including at the 1:00 minute mark of this video, in my book, and in posts here, here, and here.
I have not posted much of late on this topic, becuase I am not sure there is a lot of new news. Satellites still make more sense than surface measurement, and the GISS still is working to tweak its numbers to show more and more warming, and Anthony Watts still finds a lot of bad measurement points.
In the last week, though, the story seems to be getting out further than just the online skeptic’s community. Steven Goddard has a good article in the UK Register online. I don’t think any of the issues he covers will be new to our readers, but it is a decent summary. He focuses in particular on the GISS restatements of history:
One clue we can see is that NASA has been reworking recent temperatures upwards and older temperatures downwards – which creates a greater slope and the appearance of warming. Canadian statistician Steve McIntyre has been tracking the changes closely on his Climate Audit site, and reports that NASA is Rewriting History, Time and Time Again. The recent changes can be seen by comparing the NASA 1999 and 2007 US temperature graphs. Below is the 1999 version, and below that is the reworked 2007 version.
NASA’s original data: 1999
NASA’s reworked data: 2007
This restatement is particularly hard to justify as direct inspection of the temperature measurement points reveals growing urban heat biases, which should imply, if anything, adjustments up in the past and/or down in the present, exactly opposite of the GISS work. I have written a number of letters and inquiries asking the GISS what systematic bias they are finding/assuming that biased measurements upwards in rural times but downwards in urban times, but I have never gotten a response, nor seen one anywhere online.
HT: Anthony Watts
Update: Similar article here
"Particularly troubling are the years from 1986-1998. In the 2007 version of the graph, the 1986 data was adjusted upwards by 0.4 degrees relative to the 1999 graph. In fact, every year except one from 1986-1998 was adjusted upwards, by an average of 0.2 degrees. If someone wanted to present a case for a lot of recent warming, adjusting data upwards would be an excellent way to do it.