Why are the HadCRU and NASA GISS temperature records slightly different?

Question

A good analysis at my favorite climate blog (Open Mind) analyzes the newly released HadCRU and NCDC surface temperature data, including 2007. Here's how they look:

http://tamino.files.wordpress.com/2008/01/big3.jpg

Using a common base period:

http://tamino.files.wordpress.com/2008/01/big3z.jpg

Since 1975:

http://tamino.files.wordpress.com/2008/01/75-08.jpg

According to the blog

"The GISS/HadCRU difference seems to be because HadCRU omits the arctic while GISS estimates it by interpolation. In that case, the noted result is what we would expect: if it’s true that the arctic is the fastest-warming part of the planet, and HadCRU omits that fastest-warming region, we would expect their estimate to be low."

So I assume from this that there are no temperature stations in the arctic? Can anyone confirm this?

The full blog entry as always is very interesting:

http://tamino.wordpress.com/2008/01/24/giss-ncdc-hadcru/#more-556

Answer 1

i didnt get it

Answer 2

I tried to find temperature readings from the Geographic North pole and the best I could find was North Pole Alaska. So from my web research I would say they don't have any temperature stations in the Arctic. Why? I'm not sure, since they have them in the Antarctic and in the oceans. I can't even think of a good guess of why not, since they have those cool vehicles that they use to travel across Antarctica.

Edit: I also agree with Tamino's conclusion that by if not sooner than 2015 we will know if GW has stopped and we hit a new equilibrium, reversed or continues. But even if I'm right and 2008 does turn out to be colder than 2007 it's still too soon to determine if the trend has changed.

Answer 3

Yes, there are no permanent atmospheric climate monitoring sites in the arctic ocean.  The reasons are it is a very harsh environment, the shifting ice makes it impossible to fix a location for the sensor, and because the ice melts no kind of sensor has any kind of reasonable lifetime.  Imagine trying to deploy a surface buoy system in the arctic like the TAO array.  You would get one season, the buoys would be crushed, and you would have to redeploy them in the spring.  Ice-mounted systems would suffer a reverse fate.  

It is simpler to deal with in the antarctic since the ice doesn't melt or move as much.

Answer 4

Thank you for providing this information. It looks like you answered your own question though. Also, HadCRU and GISS weigh the land surface temperatures vs ocean surface temperatures slightly differently.

Edit, For Mikira:

According to HADCRU, “2008 is set to be cooler globally than recent years (Keep reading) say Met Office and University of East Anglia climate scientists, but is still forecast to be one of the top-ten warmest years.”

"The fact that 2008 is forecast to be cooler than any of the last seven years does not mean that global warming has gone away. What matters is the underlying rate of warming - the period 2001-2007 with an average of 0.44 °C above the 1961-90 average was 0.21 °C warmer than corresponding values for the period 1991-2000."

http://www.metoffice.gov.uk/corporate/pr...