Climate Change

One of the major issues facing the world is the possible weakening of the Gulf Stream. Just off Greenland, a whirlpool of salty water is being flushed away by arctic melting. This whirlpool is the beginning of the Great Conveyor Belt, an undersea river that helps propel the Gulf Stream as it swings around North America. High salt content in the Greenland Sea causes cold water to sink, providing the thrust that starts the Conveyor.

The current is so deep and dense that when it turns northward, it draws warm Pacific Ocean water over the surface of the Atlantic. This warm stream evaporates when it reaches the North Atlantic, helping keep Europe and the Eastern United States mild. If the Conveyor Belt falters or shuts down, the Gulf Stream would slow and many temperate regions would experience extreme cold.

The Gulf Stream itself can never completely shut down, because it is also pulled by wind and gravitational forces, but even a small decline would be catastrophic. During the height of our most recent Ice Age, 20,000 years ago, the Gulf Stream was operating at two-thirds its current strength. The Conveyor Belt accounts for half of the Streams pull, and there has been a 20% decrease in its outflow since 1950. This corresponds with reduced inflow at the beginning of the loop, further exacerbating the situation.

It was previously thought a transition between Glacial and Interglacial Ages would be gradual, but evidence discovered in the Greenland ice pack shows that it's more like flipping a switch. We're either in an Ice Age or we're not. Once that switch is flipped, there's no turning back; it can begin within 2 or 3 years. In our case it would be more of a "mini" Ice Age, if you will. Conditions could start resembling the Little Ice Age that occurred 1300-1850, during our current Temperate period.

Imagine longer, more severe winters; spring, summer, and fall ever shorter. Eventually winter would prevail over the Northern Hemisphere most of the year, while the rest of the world continues warming. Rain would cease in many areas of the Southern Hemisphere. Under this scenario, massive displacement of people, due to drought and famine, would cause unrest leading to wars. That's why the Pentagon is studying this. It was their report that got the attention of the media.

Most projections indicate these changes could happen in the next couple of decades to half century. The actual turning point is unknown. The world has warmed 0.7 Celsius (1.26 Farenheit) since just before the beginning of the Industrial Revolution. Once 2.0C (3.6 Farenheit) is reached, the damage is considered irreversible. We are heading there fast, with the highest average temperatures occuring since 1990. Scientists world-wide are working together to solve this problem, but unless something is done now to address the underlying causes, it really might be too late.

Sources:

http://www.msnbc.msn.com/id/5052363/

http://www.commondreams.org/views04/0130-11.htm

http://www.commondreams.org/headlines05/0130-02.htm

http://www.ems.org/climate/pentagon_climate_change.html

http://www.ems.org/climate/pentagon_climatechange.pdf

http://www.guardian.co.uk/climatechange/story/0,12374,1083419,00.html

http://www.whoi.edu/institutes/occi/currenttopics/abruptclimate_joyce_keigwin.html

http://www.whoi.edu/institutes/occi/currenttopics/climatechange_wef.html

http://www.whoi.edu/institutes/occi/currenttopics/abruptclimate_15misconceptions.html

http://www.whoi.edu/institutes/occi/currenttopics/abruptclimate_rcurry_pr.html

http://www.whoi.edu/institutes/occi/currenttopics/abruptclimate_currents10no2_riverruns.html