Sunday, October 18, 2009
It's not simply global warming... IT's CLIMATE CHANGE
Does Earth's climate system have an 'Achilles' heel'?
Here is a simplified description of some basic ocean-atmosphere dynamics that regulate Earth’s climate:
The equatorial sun warms the ocean surface and enhances evaporation in the tropics. This leaves the tropical ocean saltier. The Gulf Stream, a limb of the Ocean Conveyor, carries an enormous volume of heat-laden, salty water up the East Coast of the United States, and then northeast toward Europe.
Two views of the Gulf Stream --------->
The global ocean is not a static pond, but a body in constant motion. Winds blow across its surface, generating waves and currents, while the pull of gravity gently sloshes it back and forth in a lunar rhythm of tides. But beneath these familiar surface motions is a seemingly mysterious process which has major implications for Earth's climate: the Great Ocean Conveyor (also called the thermohaline circulation).
The Conveyor is one of the great unknowns in humanity's unintentional climate change experiment. Surface water, warmed at the equator, moves to high latitudes where it releases heat to the atmosphere. As a result, the water cools - becoming denser - and sinks to the deep ocean. Deep water slowly travels through the oceanic abyss, eventually mixing up to the surface in distant parts the world, as much as 1000 years later.
This oceanic heat pump, is an all important mechanism for reducing equator-to-pole temperature differences. It moderates Earth’s climate, particularly in the North Atlantic region. Conveyor circulation increases the northward transport of warmer waters in the Gulf Stream by about 50 percent. At colder northern latitudes, the ocean releases this heat to the atmosphere—especially in winter when the atmosphere is colder than the ocean. The Conveyor warms North Atlantic regions by as much as 5° Celsius and significantly moderates average winter temperatures.
The transfer of energy, heat, by the great Ocean Conveyor is what lets Norway, which is as far north as Manitoba Canada have annual temperatures 20 degrees warmer. If not for the North Atlantic loop of the Conveyor, European winters would be much colder. London would be like Laborador, Berlin might have the climate of Edmonton Alberta, which lies at the same latitude, while Stockholm might be more like Nome, Alaska.
(CBS/AP) OCT 16, 2009
The North Pole will turn into an open sea during summer within a decade, according to data released by a team of explorers who trekked through the Arctic for three months.
NBC Nightly News Channel - Oct. 15: The Arctic Ocean will be an "open sea" almost entirely free from ice within just ten years. Ice cover during the summer months will have entirely disap... read more Oct. 15, 2009
The Arctic Ocean will be an "open sea" almost entirely free from ice within just ten years. Ice over during the summer months will have entirely disappeared within 20 years, but most of the decrease will happen before 2020.
So Santa needs a new home ... What else?
Unfortunately it may get even more confusing...
Out of the frying pan and in to the freezer ?
In 2005 Nature , published the results of a study showing that the Gulf Stream current (the one that keeps Europe warm despite the fact that the UK is as far north as Hudson Bay) has slowed down by about 30% since 1957. The study noted that the slowing has mostly happened in the years since 1998.
Further studies indicate that during that time due to all the fresh water runoff from melting ice, North Atlantic waters have become steadily less salty in the places where cold, salty water is supposed to sink, starting the Great Conveyor. Fresher water is less dense than ocean water and does not sink as readily. The Great Conveyor is slowing down.
Records and evidence of past climates—from deep-sea sediments and ice-sheet cores—show that the Conveyor has slowed and shut down several times in the distant past. This shutdown stopped the heat transfer to the North Atlantic and brought about colder climates and mini -Ice Ages. One earth scientist has called the Conveyor “the Achilles’ heel of our climate system.” (Gagosian, Robert B. Woods Hole Oceanographic Institution updated)
Something is throwing the climate out of balance. Computer models and scientists agree that it appears to be human activity and increased greenhouse gasses. The warming and freshening (i.e. reduced saltiness) in the northern North Atlantic ocean predicts a slowing or even a complete stop of the North Atlantic currents - just like the sudden cooling in the past, thousands of years ago.
This could be disastrous for eastern North America and western Europe. Average temperatures could plunge by 5 degrees C - for comparison, this is about the same difference as between the global average temperature today and during the last Ice Age, when Canada lay beneath 3000m thick glaciers. (David Suzuki Foundation, 2009)
The Comments Box is open..
What do you think?
How can people help change what could happen?
What more would you like to learn?
at 3:48 PM