Waiting For HADCRUT (Again!)

By Paul Homewood

 

Last month the HADCRUT numbers for March did not come out till after the UAH ones for April did.  They are late again this month, so I am putting out the GISS, UAH and RSS figures without waiting any longer.

 

 

	RSS	UAH	GISS
April 2013	0.22	0.10	0.50
Change from last month	0.01	-0.08	-0.09
12 month running average	0.26	0.24	0.59
Average 2003-12	0.24	0.19	0.58
Change since Sep/Oct Peaks	-0.17	-0.24	-0.22

 

 

Current temperatures are below the 12-Month averages, which are still affected by the small El Nino episode last summer. More significantly, current temperatures are also lower than the 10-Year averages.

 

 

 

It is worth making a closer comparison between the last few months and early 2002. As the MEI index below indicates, ENSO conditions have been essentially neutral since September. The previous occasion, when similar conditions prevailed for more than just a few months, was from April 2001 – May 2002. (Negative numbers = La Nina). Most of the months in between have seesawed from El Nino to La Nina, and back again.

 

http://www.esrl.noaa.gov/psd/enso/mei/

 

http://www.esrl.noaa.gov/psd/enso/mei/table.html

 

According to Trenberth et al, there is a lag of about 6 months for ENSO changes to have an effect on global temperatures, so let’s compare the GISS global temperature record between October 2001 and November 2002, with February to March this year.

 

	Average GISS Anomaly
Oct 2001 – November 2002	0.61C
February 2013 – April 2013	0.53C

 

Similar calculations using RSS, UAH and HADCRUT give much the same results. The conclusion is clear. Under similar ENSO conditions, global temperatures are currently lower than in 2002.

We need more months’ data to make a more robust comparison, but with ENSO still remaining fairly neutral, we may be able to make such a comparison by the end of the year.