The usual caveats apply: just a single number, more to understanding climate change than surface temp., etc. NASA’s GISS team has posted its global January number, with fodder for everyone to misinterpret. On one side, you could argue it’s cooling. (You’ve got to be careful in picking your starting year to make that case, but that does’t stop people from regularly doing it.) On the other side, you could argue that the five warmest Januaries in history globally have come in the last five years. Cherrypickers, have at it. Or you could just ignore the arguments and lay in a stockpile of salty snack foods in preparation for the winter Olympics.
Wait! Could we make a case that global warming threatens the winter Olympics?
Actually, you can’t get a “single number”. You can pretty much pick what you want. Let’s do that! Here’s the question:
Which temperature trend, with their 2sd error, is right?
a. GHCN: 0.076 +/- 0.010
b. Jones: 0.064 +/- 0.007
c. GISS: 0.048 +/- 0.006
d. None of the above?
Which his not to say the trend isn’t upward, but it shows how much the “experts” differ – Their error bands are obviously much wider than they think (or admit)…
We need more than one “Red Storm” to get a handle on this – if we even can – certainly there’s a lot of entrenched dogma and Hwangingin climate science to overcome.
Thanks to the co2Science.org site for Jones and GHCN – you need to pay though – apparently the “backers” like Exxon don’t have enough money to support them…
It’s reasonable to ask why the three different groups come up with different numbers, but the answer is not mysterious, and is well discussed in the literature.
The bottom line is that there is no “best method”. The appropriate approach is to look at them all, understand where and why they agree and disagree, and consider the importance of the differences. Here they all are, plotted against one another, for the period of record:
( , fig. 2)
GISS, which I’m citing here, is the more conservative of the three, based on its estimations of unsampled southern hemisphere grid boxes.
 IPCC 2001 – Chapter 2, Observed Climate Variability and Change
 Wigley et al., Proc. Natl. Acad. Sci. U. S. A., 94, 8314–8320
 Vose et al., GRL, VOL. 32, L18718, doi:10.1029/2005GL023502, 2005
Interesting graph. Doesn’t appear to match the graph I have. Where’d you get your data? Mine came from GHCN, Jones, and GISS, respectively.
Also, in the see-saw virtually irrelevent game of which year was warmest, 4 orgainizations have now “voted” that 1998 was still hottest – GHCN, NCDC, CRU and UAH.
See the footnote. Vose et al., GRL, etc.
Oops. Missed that.
I am doing research trying to find as many graphs as I can that show a temperature raise or decline in the past years. if you know of any, please e-mail a link to email@example.com