Answer to What Ended the Last Ice Age May Be Blowing in the Winds, Paper Says

[OKIsItJustMe]

http://www.earth.columbia.edu/articles/view/2707

Answer to What Ended the Last Ice Age May Be Blowing in the Winds, Paper Says

A Chain of Past Natural Events May Hold Lessons for the Future

posted: 2010-06-25

Scientists still puzzle over how Earth emerged from its last ice age, an event that ushered in a warmer climate and the birth of human civilization. In the geological blink of an eye, ice sheets in the northern hemisphere began to collapse and warming spread quickly to the south. Most scientists say that the trigger, at least initially, was an orbital shift that caused more sunlight to fall across Earth’s northern half. But how did the south catch up so fast?

In a review paper published this week in the journal Science, a team of researchers look to a global shift in winds for the answer. They propose a chain of events that began with the melting of the large northern hemisphere ice sheets about 20,000 years ago. The melting ice sheets reconfigured the planet’s wind belts, pushing warm air and seawater south, and pulling carbon dioxide from the deep ocean into the atmosphere, allowing the planet to heat even further. Their hypothesis makes use of climate data preserved in cave formations, polar ice cores and deep-sea sediments to describe how Earth finally thawed out.

“This paper pulls together several recent studies to explain how warming triggered in the north moves to the south, ending an ice age,” said study co-author Bob Anderson, a geochemist at Columbia University’s Lamont-Doherty Earth Observatory. “Finally, we have a clear picture of the global teleconnections in Earth’s climate system that are active across many time scales. These same linkages that brought the earth out of the last ice age are active today, and they will almost certainly play a role in future climate change as well.”

Earth regularly goes into an ice age every 100,000 years or so, as its orientation toward the sun shifts in what are called Milankovitch cycles. At the peak of the last ice age, about 20,000 years ago, with New York City and large parts of Europe and Asia buried under thick sheets of ice, Earth’s orbit shifted. More summer sunlight began falling on the northern hemisphere, melting those massive ice sheets and sending icebergs and fresh water into the North Atlantic Ocean.

It may sound counterintuitive, but the paper says freshening of the North Atlantic triggered a series of cold spells in Greenland and northern Europe by shutting down the Gulf Stream current, which usually carries warm water north from the equator. Sea ice spread across the North Atlantic, bringing bitter cold winters to Europe and profoundly reshaping the planet’s wind belts.

With the North Atlantic in a deep freeze, the tropical trade winds shifted south, bringing dry spells across much of Asia and rain to normally arid regions of Brazil. The displaced winds moved not only rain further south, but hot air and warm seawater, heating up the southern hemisphere.

The southern hemisphere westerly winds also shifted south, bringing warm air and seawater to the mid-latitudes. By about 18,000 years ago, mountain glaciers in South America and New Zealand started to melt as the displaced winds blew warm air their way. By 16,000 years ago, the glaciers had beaten a spectacular retreat. This shift in westerly winds would also amplify the warming in both hemispheres by resetting the planet’s thermostat, as Anderson has proposed in an earlier study in Science. The displaced westerlies caused heavy mixing in the Southern Ocean around Antarctica, pumping dissolved carbon dioxide from the water into the air. Ice core records show that between 18,000 and 11,000 years ago atmospheric carbon dioxide levels rose from 185 parts per million to 265 parts per million. (Today levels are 393 parts per million, after a sustained rise during the industrial era.) The infusion of carbon dioxide came just as the planet’s orientation was shifting, and summer sunlight to the northern hemisphere was declining, at about 11,000 years ago. The boost in carbon dioxide may have prevented Earth from falling into another ice age, the scientists say.

…

[Hawkowl]

1. The planet is trying to shake off the plague of humanity

That is what I think this massive eruption of carbon from the ocean floor in the gulf is all about. I have a very strong, sickeningly gut feeling that we are only seeing the beginning of the disaster in the Gulf of Mexico. I don't even think the oil eruption is the greatest danger. I think a massive eruption of the methane hydrates, with the associated tsunamis and poisonous air/water could wipe out tens of millions of people. It could even alter the ocean current as detailed in the OP and we would have an instant cataclysmic climate change.

I hope I'm just another paranoid, environmental whack job.

[OKIsItJustMe]

2. Re: Methane Hydrates

A number of us are concerned by the “http://en.wikipedia.org/wiki/Clathrate_gun_hypothesis">Clathrate gun hypothesis.”

This study suggests we should look elsewhere:
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=251890&mesg_id=251890">Higher wetland methane emissions caused by climate warming 40,000 years ago — No clathrate gun

[Hawkowl]

4. Very interesting link

Thanks for the link: “Clathrate gun hypothesis.” Lots of information and links there. I found the following to be particularly disturbing:

"It may be possible to explain past marine extinctions by the scrubbing effect. If an inert gas is bubbled through water, the surface of each bubble acts as a semi permeable membrane. Gases diffuse across this membrane according to their concentration inside and outside the bubble. The result of bubbling methane through the ocean is to deplete the oxygen dissolved in the water, leading to ocean anoxia.

The consequences of a methane-driven oceanic eruption for marine and terrestrial life are likely to be catastrophic. Figuratively speaking, the erupting region "boils over," ejecting a large amount of methane and other gases (e.g., CO2, H2S) into the atmosphere, and flooding large areas of land. Whereas pure methane is lighter than air, methane loaded with water droplets is much heavier, and thus spreads over the land, mixing with air in the process (and losing water as rain). The air-methane mixture is explosive at methane concentrations between 5% and 15%; as such mixtures form in different locations near the ground and are ignited by lightning, explosions and conflagrations destroy most of the terrestrial life, and also produce great amounts of smoke and of carbon dioxide. Firestorms carry smoke and dust into the upper atmosphere, where they may remain for several years; the resulting darkness and global cooling may provide an additional kill mechanism. Conversely, carbon dioxide and the remaining methane create the greenhouse effect, which may lead to global warming. The outcome of the competition between the cooling and the warming tendencies is difficult to predict.<2>"

The effects of this eruption in the gulf is just mind boggling. Worst case scenarios can not be predicted with very much accuracy. However, if this eruption can not be stopped very soon, I unshakably believe that the environmental effects will make Chernobyl look like a day at Disneyland.

[N_E_1 for Tennis]

3. Don't feel alone.

Your not a "whack job" , you just may be a prophet.

But to the powers that created us, I hope we are wrong.

Tears shedding ... for our decedents.