 exploring, preserving and protecting the genetic diversity of the world's oceans
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OGL Newsletter
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Greetings!
Your body's circulatory system is critical to your health and survival, supplying oxygen and nutrients throughout your body while at the same time removing waste. No wonder your pulse and BP are the first things that get checked when you visit the doctor's office! You may be surprised to learn that the world's oceans are also interconnected by a circulatory system, and it plays just as big a role in governing the health of the marine environment. Keep reading to find out what scientists are learning as they take the pulse of thermohaline circulation.
And, as always, follow our expeditions and other news from the marine world on our Facebook and Twitter pages!
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Thermohaline Circulation: The lifeblood of our oceans
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The Great Ocean Conveyor Belt
Image: Smithsonian Institution
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Water of the world's ocean is in constant motion in a closed looped flow known as "thermohaline" circulation (THC) - "thermo" because it transfers heat energy, and "haline" because it transfers salt. But the current is not limited to just salt and heat; migrating animals, plankton, oxygen, carbon dioxide, detritus and pretty much anything not attached to the sea floor come along for the ride. Back in 1991, Wallace Broeker coined the term "great ocean conveyor belt" for this transport mechanism, and the sobriquet stuck.
What keeps the water in motion is differences in temperature and salinity between the icy cold polar caps and the warm, sunny equatorial regions. Warm, less salty surface water is lighter (less dense) than the cold salty (denser) water below and so it floats on top. In the Atlantic, this surface water is channeled up toward the Arctic via the Gulf Stream and the North Atlantic Drift. As the water approaches the pole it gets very cold and freezing starts. Because sea ice is made of fresh water, it leaves its salt behind as it freezes. This makes the remaining water around it saltier and heavier. This cold, salty, dense water then sinks swiftly downward to form the North Atlantic Deep Water (NADW) which flows steadily southward to merge with Antarctic Bottom Water (AABW), even colder saltier water that sinks from the surface in the Antarctic. Like a pumping heart, sinking cold water keeps the circulation moving along the sea floor northward into the Pacific where it slowly warms and rises as it crosses the equator and mixes with warmer, less salty water. Here, warming in the equatorial regions helps propel it on its way back westward through the South China Sea, across the Indian Ocean and back to the Atlantic to complete the circuit.|
Retraction of polar ice in Greenland at the same time of year over recent consecutive summers provides strong evidence for global warming and dilution of North Atlantic waters.
Satellite Images: NOAA
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As long as the earth's climate remains stable, this flow could go on forever. However, scientists have calculated that a rise of as little as 3-4oC in average global temperature (expected by the end of the century) could slow THC flows by 20-50% - or even bring it to a grinding halt! This is because, as the climate warms and polar caps shrink, less ice forms and more ice melts, diluting and warming the surface water, slowing the sinking action, and weakening the pump that powers the THC. When our own arteries clog, illness and death cannot be far behind. The same is true for the THC. A weakened THC would likely accelerate climate change all over the world. Without a vigorous Gulf Stream, North America would be far colder. Equatorial regions would become far hotter. Changes in sea temperature would interrupt food chains that support life in the oceans and provide food to millions of people.
So when you think about global warming, don't think this just means balmy winters. A halt of the THC would be by far the greatest ecological challenge in the history of mankind. Far fetched? Maybe. But maybe just enough impetus to make us start to rethink our ways, reduce our impact on atmosphere, climate and oceans, and find ways to keep our oceans healthy and our marine life thriving.
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| OGL at the NEOSEC Ocean Literacy Summit | |
On November 2, OGL staffers Sandra Dedrick and Chris Reif reached out to grade school educators at the biennial NEOSEC Ocean Literacy Summit, held at the University of Rhode Island's Graduate School of Oceanography in Narragansett. There, approximately 200 attendees learned how to engage student interest in our oceans, exploring a wide range of ocean-related topics from biology to physics and geology to archeology.
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OGL Research Technician Sandra Dedrick explains the role of DNA in environmental conservation to a conference attendee at
NEOSEC 2012.
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Adopt a Marine Mammal Species!
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We're doing something different this year for OGL's Annual Fall Appeal by asking you to Adopt a Marine Mammal Species. See how you can help to save our closest relatives in the ocean. By adopting a marine mammal species, you help to support genomic research that can help prevent the decline of some of the most intelligent and social (not to mention the cutest!) creatures ever to swim the sea.
Not ready to adopt? Please consider helping OGL to continue its good work in preserving and protecting the biodiversity of our world's oceans by contributing any amount today. It's easy! Just visit our Donations page at http://www.oglf.org/Support.htm, where you'll find instructions on how to donate by check or by credit card.
Thanks in advance for your support!
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| Coming Soon... | |
New England groundfishing: an industry in crisis?
In September, the US Department of Commerce officially declared the New England groundfishing industry to be in a state of disaster, enabling Congress to obtain up to $100M in assistance for fishermen for the 2013 fishing season. Find out next time what has happened to our country's oldest industry, and what's being done to keep it alive.
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Since they first settled in America, New Englanders have sustained themselves on the rich supply of cod, halibut, flounder, haddock, perch and striped bass found off their coast.
Image: USA Today
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DONATE TO OGL
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Want to help OGL document and preserve the spectacular genetic diversity of our world's oceans? Visit http://www.oglf.org/Support.htm
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