Weakening Ocean Conveyor Will Fundamentally Change Northern Hemisphere Climate

Relationship Between Collapsing Ice Sheets And Gulf Stream Shut Down

Most people know that the Gulf Stream is responsible for keeping Northern Europe and the northern Western Hemisphere temperate. It is the driving component of a planetary current system known as the Great Ocean Conveyor Belt or more obtusely, the Meridional Overturning Circulation (MOC).

The current conveys warm water from the lower latitudes northwards, where it acts as a massive heat exchanger between air and water. The warm water heats the atmosphere west of Europe, which allows the region to enjoy a reasonable climate.* The returning cold current provides atmospheric air conditioning for the United States.

What most people don’t know is that the Gulf Stream has mostly likely been irrevocably compromised by global warming, a condition that may very well lead to what scientists are now calling abrupt climate change.


The North Atlantic Ocean Current is driven by two variables: water temperature and water density. Here is how it works: warm, salty, lower density water flows north along the North American Atlantic Coast and then north and north by east toward Europe. In the northern environs, the heat is released into the atmosphere, while at the same time, winds off of Greenland and Canada cool the water.

The cool salty waters increase in density and sink to the bottom and creates a current that flows back south.

The current threat lies in the massive amount of ice melt taking place on Greenland and northern Canada, a process which which dumps trillions of gallons of fresh water into the ocean, which decreases the water’s salt content and therefore it’s density. If enough fresh water flows into the ocean, the cooling waters will not sink, and the conveyor will slow and eventually stop.

According to a 2003 report prepared for the notoriously liberal US department of defense, the following scenarios would apply to a shut down of the MOC:
• Annual average temperatures would decrease up to 5° F in North America, and up to 6° F in northern Europe. It is estimated that a new Ice Age could be brought on by a 10° F drop.
• Temps in the Southern Hemisphere would increase about 4° F.
• Multi-year droughts –which are already increasing dramatically – would cause even more stress on agriculture and especially water supplies.
• Extreme weather would spike even further than it has in the past decade.

There are signs that this process has begun, but it isn’t possible yet to prove it. The fact that Greenland’s land glaciers are melting at an unprecedented rate is not debatable. Scientists who have been modeling the pace of global warming have revised their projections upward in terms of how fast the pole regions are changing.

Once the Gulf Stream weakens and dies, all bets are off.

* Note that when the English and French sailed straight west, they ended up far north in the Maritimes in terms of latitude.

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