WORLD CLIMATE REPORT on: A Sea Surface Story[1]

 22 May 2008

OCEANCLIMATE and related websites (see: Bottom Box) are looking for explanation why global temperatures had run into a significant cooling for three decades, starting in winter 1939/40 and being back to pre-WWII level only in the 1990s. (Details: Here). 

Now WORLD CLIMATE REPORT discusses a recent work by Hobson et al.[2] with the title “Ocean surface warming: The North Atlantic remains within the envelope of previous recorded conditions”, concluding that “the real world is not cooperating with expectations from predictions from numerical climate models”.

According Hobson et al: “The North Atlantic has undergone a net warming since 1976, and this recent warming parallels similar warming from 1910 to 1945. Between these two recent warming eras the North Atlantic cooled by 1°C.”, as indicated in the figure, which shows the mean latitudinal position of the isotherms over varying time intervals based on data availability thresholds.

Figure:  The mean latitudinal position north for the 12°C (black, from 1911 to 2005), 15°C (blue, from 1856 to 2005) and 18°C (red, from 1876 to 2005) isotherms. The length of timescale varies because of variations in data availability.

WORLD CLIMATE REPORT comments this as follows: Guess what year had the most northerly extent of the isotherms – 1932!!! The second highest ranking year was …. 1898! The remaining years ranked third to tenth were 2005, 1952, 1998, 2001, 1939, 1899, 1936, and 2003. These results, along with others, led the team to conclude “We have shown that the current ‘warm era conditions’ do not eclipse prior ‘warm’ conditions during the instrumental record.” Furthermore, they write “In short, our analyses suggest in recent years the position of summer isotherms in the North Atlantic has not moved markedly beyond the window of previous values.”

OCEANCLIMATE welcomes the clear sign that the scientific community is paying more and more attention to the role of the oceans within the climate system. This may pave the way to present also the reasons for the global cooling from 1940- ca. 1980 one day, and to acknowledge that climate is  - properly understood – the blueprint of the oceans and seas.  

[2] Hobson, V.J., C.R. McMahon, A. Richardson, G.C. Hays. 2008. Ocean surface warming: The North Atlantic remains within the envelope of previous recorded conditions. Deep-Sea Research, 55, 155–162.