Climate Letter #1411

For readers who are not up to date, my Climate Letters are now being dedicated more and more to unveiling and interpreting information that can be found on the Weather Maps published by the University of Maine.  I have been studying these maps every day for about four years, and never fail to find something interesting.  The information that’s available is monumental, often hard to find anywhere else.  It should have high value for anyone interested in understanding the many underlying aspects of climate change at the natural level.  The maps are sometimes referred to in websites but otherwise do not get the kind of attention they deserve, and that needs to change.  I am just going to show you things I see, make a few comments, and hope you will find it rewarding.

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Today I want to point out some things about ocean surface temperatures, as found on this chart, which shows current anomalies over a base averaging 34 years:

Ocean surfaces, you may recall, have warmed up much less than land surfaces during the current era of global warming.  They are responsible for a full 70% of the weighting of the average global temperature increase because of their relatively large area.  That’s not all.  This chart shows that the average gain for ocean surfaces in the Northern Hemisphere has been growing quite a bit faster than the Southern in recent decades.  Moreover, as you can see for yourself, the total area of SH oceans is quite a bit larger than that of the NH, and thus the SH oceans have an unduly large influence on the ocean total that so strongly affects the overall global numbers we hear so much about.

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Why is there such a big difference in the warming rates of north and south?  The map provides a good clue, found in all of the blue color that lies around a large majority of the rim of the Antarctic continent.  I believe the well-cooled water is there because it is floating away from a growing amount of ice that has melted from around the edges of the continent.  That water has low salt content along with low temperature, which helps in keeping it at the surface.  (Other charts show a sharp reduction in sea ice extent and volume these days, plus whatever may be coming off the underbellies of glaciers at the coastline.)  The effect even appears to have an influence extending far to the north, approaching the equator.  Greenland is also known for producing a similar effect in the Atlantic, but not as pronounced at this time .

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Some scientists, most notably James Hansen, have written about the possibility that an acceleration of melting of the two major ice sheets could take a large, but temporary, bite out of the global warming trend that is now in place.  We may be observing a small part of that bite already happening, and gaining some benefit from it.  Hansen has also warned that once the melting is done with the sea surface temperatures would come roaring back with a vengeance, and the air above them as well, so there is no room for complacency.

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BuzzFeed News has provided an interactive map (slow-loading) showing how temperatures have changed in locations all over the world, both land and sea, except for the polar regions, plus more information about various sorts of climate change.

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