By Paul Homewood
While Obama is imploring us to stop the global warming that is bringing us “the devastating impact of raging fires, and crippling drought, and more powerful storms”, it would seem to be a good idea to see exactly what global temperatures have been doing in the last year.
First, let’s look at the December numbers, as there have been some significant changes.
|Change from last month||-0.09||-0.07||-0.25||-0.24|
|12 month running average||0.19||0.16||0.44||0.56|
[Remember all four sets are based on different base periods, so the absolute numbers are not directly comparable]
Points to note:-
- Although HADCRUT and GISS show larger drops than the satellites, UAH and RSS both showed falls earlier in Oct/Nov, that were not matched by the others.
- All three sets share a remarkable degree of agreement, in that the current 12-month average is running just below the 10 year average.
- This month’s temperatures are remarkably low by historic standards. For instance, in the last ten years, there have only been three months when the HADCRUT figure has been lower.
- ENSO conditions have been neutral for the last three months, and the temperature drops in the last couple of months appear to reflect the ending of a short lived El Nino conditions over the summer. More detail here.
- The retrospective changes made by GISS, see here, are included in the above analysis. They tend to affect comparisons prior to 1998, rather than with recent years.
- Quick analysis of HADCRUT data shows a larger drop of 0.41C in Northern Hemisphere temperatures, though Southern Hemisphere is also down by 0.09C.
Before we look at temperatures, let’s just see what the ENSO index has done this year.
The monthly figures for 2012 are :-
|Dec 2011/Jan 2012||-1.046|
The average for the year is +0.15, so it would be reasonable to classify it, overall, as ENSO neutral. Probably the last time neutral conditions applied for a sustained period was between April 2001 and March 2002. The current running averages for all four sets are close to or below the average seen in 2002.
Understanding this background is important when reviewing temperatures during the year.
The following graphs compare the annual temperatures over the last 10 years. None of them show any evidence of an increasing trend.
Perhaps the President might care to tell us what global warming he is talking about!
Temperature datasets are available below.