Rapid Climate Change: Ice Age and Drought

Fortune has a good article on the risk of rapid climate change. Many people think of climate change as a gradual process spanning over decades. In this article they discuss the risks of radical changes to the climate happening in the span of a few years.

Climate researchers began getting seriously concerned about it a decade ago, after studying temperature indicators embedded in ancient layers of Arctic ice. The data show that a number of dramatic shifts in average temperature took place in the past with shocking speed—in some cases, just a few years.

One looming concern is not warming, but actually having the ocean thermal conveyor that keeps Europe mild shutting down. This might help explain European's more proactive approach to climate change mitigation. But, I think that the structure of European economies (less CO2 intensive economy per capita) vis-a-vis the US and public attention to the issue are more the drivers.

The eastern U.S. and northern Europe, it seems, are warmed by a huge Atlantic Ocean current that flows north from the tropics—that's why Britain, at Labrador's latitude, is relatively temperate. Pumping out warm, moist air, this "great conveyor" current gets cooler and denser as it moves north. That causes the current to sink in the North Atlantic, where it heads south again in the ocean depths. The sinking process draws more water from the south, keeping the roughly circular current on the go.

But when the climate warms, according to the theory, fresh water from melting Arctic glaciers flows into the North Atlantic, lowering the current's salinity—and its density and tendency to sink. A warmer climate also increases rainfall and runoff into the current, further lowering its saltiness. As a result, the conveyor loses its main motive force and can rapidly collapse, turning off the huge heat pump and altering the climate over much of the Northern Hemisphere.

What I find interesting is that US Government strategic planners are now seriously contemplating the geo-political effects of rapid climate change. What would happen if much of Western Europe froze, and agricultural belts shifted worldwide?

Adam Smith

Comments

[kate]

Another interesting aspect of the 'rapid' change problem is just to consider the timescales in question. A February 6th article in Science looked at the effects of climate change in Peru over the last 50,000 years. They found that South American temperatures rose 5 degrees over about 5 millenia after the last ice age as compaired to North America (changes around 1 degree C per century). This difference in the rate of temperature change between continents strikes me as fairly dramatic. They used this discrepancy to help explain why there's so much more biodiversity in the Andes Mountains compared to similar areas in North America. Where the temperature change was slow, more species could succesfully adapt.

The IPCC is predicting a minimum of one degree Celsius of warming in the Andes by the end of this century. This type of swift (1 degree C per century!) change has not been seen in Peru in the last 50,000 years so the scientists believe that the warming will greatly impact the area. Although deforestation and extintions are expected, the change will help farmers by giving them more land for agricultural development.

[Kate]

I just noticed that the report that Andrew Marshall commissioned is now being metioned in a few other places...with "shocking" headlines and conclusions.

The Drudge Report linked to an article in the Gardian yesterday, Now the Pentagon tells Bush: climate change will destroy us and Yahoo News carried a London AFP article, Leaked Pentagon report warns climate change may bring famine, war. Both articles were written on the 22nd.

[julian]

I would like to refer you to "Antarctic studies throw cold water on global warming" by Bernard Switalski 24 Nov 2004 on 70south.com.news where the figures for Antarctic cooling over the past 4 decades, and glacial ice expansion are given. Julian

[Tom]

In the interest of discussion, here is a link to the story mentioned in the post above:

Antarctic studies throw cold water

Two things jump out, the post is from November 2004 but it is a reprint of a story from March 2002 (not that I have a problem with 2002, it just seems odd) and the article refers to people who believe that climate change is happening as "global warming alarmists" - not exactly subtle.

For the counter argument to the Nature article that spurred Switalski's post (Doran et al, 2002), check out

Antarctic cooling, global warming?

by the folks at Real Climate.

And if you are interested in climate change, add Real Climate to your RSS feed. It is a great site.

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