[Coral-List] La Nina and global warming

Bruno, John F jbruno at unc.edu
Sun Nov 14 06:55:39 EST 2010

Date: Thu, 11 Nov 2010 12:49:48 -0500
From: Eugene Shinn <eshinn at marine.usf.edu<mailto:eshinn at marine.usf.edu>>
Subject: [Coral-List] La Nina and global warming
To: coral-list at coral.aoml.noaa.gov<mailto:coral-list at coral.aoml.noaa.gov>

 By now list readers should know it is difficult to get geologists overly
wound up over climate change.

Most geologists are familiar with the science in support of Anthropogenic Global Warming (AGW).  For example, the Geological Society recently released a position statement on climate change, that you can read here:  http://www.geolsoc.org.uk/gsl/views/policy_statements/climatechange

It is a great tutorial and explains how climate variability of the past, rather than refuting AGW, in fact strongly supports it.  For example, from the report:

"When was CO2 last at today’s level, and what was the world like then?

The most recent estimates35 suggest that at times between 5.2 and 2.6 million years ago (during the Pliocene), the carbon dioxide concentrations in the atmosphere reached between 330 and 400 ppm. During those periods, global temperatures were 2-3°C higher than now, and sea levels were higher than now by 10 – 25 metres, implying that global ice volume was much less than today36. There were large fluctuations in ice cover on Greenland and West Antarctica during the Pliocene, and during the warm intervals those areas were probably largely free of ice37,38,39. Some ice may also have been lost from parts of East Antarctica during the warm intervals40. Coniferous forests replaced tundra in the high latitudes of the Northern Hemisphere41, and the Arctic Ocean may have been seasonally free of sea-ice42."

     Seriously, we all know sea level has been rising for the past
18,000 years and according to tide gauge data sea level at Key West
came up roughly one foot in the past 100 years! Is there any
scientific reason why it should stop short of its last high stand?

Indeed there is.  Due to the earth's inclination and solar output ~110,000 YBP, global temperature was roughly 1.5C higher than during the present interglacial.  This is precisely why we expect the equilibrium sea level to be in this range if we artificially warm the earth by 1.5C.  It will take centuries to get there, but it is almost inevitable thanks to anthropogenic greenhouse gas emissions.

     Many of us older types come from a long-standing culture that
says science should be pure and not influenced by politicians,
kind-of-like separation of religion and government.

Unlike U.S.-style church and state separation (which is meant to induce bidirectional neutrality), surely you'd agree that science should inform policy decisions.

     The winds have changed recently, and we can only hope our
science will weather the new and evolving political climate. Gene

On that we can agree!

Irie, JB

John F. Bruno, Ph.D.
Associate Professor
Department of Biology
The University of North Carolina at Chapel Hill
jbruno at unc.edu<mailto:jbruno at unc.edu>

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