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For those who dont know, the Younger Dryas was a ~1,000 period about 12-11,000 years ago in which the Earth cooled rapidly about a 1,000 years after the last ice age or advance had ended - the Younger Dryas was a reversal of the warming trend that marked the beginning of our current interglacial period.
The Younger Dryas is believed to be a lesson for today, a case of history repeating itself. When the ice started receding vast glacial lakes in North America drained into the oceans with the northern Atlantic getting hit hard either shutting down or greatly reducing the warming effect of the gulfstream current traveling up the US eastern seaboard and heading for Iceland and Europe. As Arctic ice and the Greenland ice sheet continue to melt it is feared the influx of this cold fresh water will trigger something similar to the Younger Dryas.
The problem of drawing too many conclusions from the Younger Dryas is that conditions are very different. Back then vast ice sheets still covered much of the northern hemisphere and sea levels were much lower with higher salinity levels as fresh water was still locked up in ice sheets. The Bering land bridge was probably still exposed so Arctic currents were different and the Mediterranean may have been blocked off at Gibralter or getting less flow from the Atlantic. Today the oceans have risen and taken in most of the fresh water formerly locked up in northern ice fields. The earth's tilt back then was less inclined, closer to the minimum tilt as opposed to the maximum we're closer to today.
The Gulfstream is a product of the Earth's spin, winds coming off N America, and the configuration of continents with S America catching water coming around S Africa sending it northward to the equator where it flows west into the Caribbean and between Florida and Cuba into the N Atlantic on to Europe. That conveyor belt will exist regardless of any ice sheets or global warming, its just a matter of how far north the warmer water can get before sinking and returning southward. If the Arctic is warmer, the current travels further north. But the gradual melting of the Greenland ice sheet will inhibit the northern extent of the gulfstream current, even slowing the current. This delays the migration of the gulfstream up into the Arctic long enough for the next ice age to take hold.
If not for the factors causing ice ages, it seems to me current conditions would eventually melt northern ice and the gulfstream would travel up into the Arctic bringing greater warmth to the northern latitudes all across the world. But that wont happen because just as the world warms up, the eccentricity of the earth's orbit increases and the axial tilt decreases so less sunlight hits the earth, especially at higher latitudes and the ice returns.
If we could warm the world enough to melt northern ice before the orbit forces the next ice advance, could we reduce the impact of ice ages? If we could "help" the gulfstream carry more, warmer water even further north toward the Arctic, would that help prevent or reduce the growth of ice sheets?
The Younger Dryas is believed to be a lesson for today, a case of history repeating itself. When the ice started receding vast glacial lakes in North America drained into the oceans with the northern Atlantic getting hit hard either shutting down or greatly reducing the warming effect of the gulfstream current traveling up the US eastern seaboard and heading for Iceland and Europe. As Arctic ice and the Greenland ice sheet continue to melt it is feared the influx of this cold fresh water will trigger something similar to the Younger Dryas.
The problem of drawing too many conclusions from the Younger Dryas is that conditions are very different. Back then vast ice sheets still covered much of the northern hemisphere and sea levels were much lower with higher salinity levels as fresh water was still locked up in ice sheets. The Bering land bridge was probably still exposed so Arctic currents were different and the Mediterranean may have been blocked off at Gibralter or getting less flow from the Atlantic. Today the oceans have risen and taken in most of the fresh water formerly locked up in northern ice fields. The earth's tilt back then was less inclined, closer to the minimum tilt as opposed to the maximum we're closer to today.
The Gulfstream is a product of the Earth's spin, winds coming off N America, and the configuration of continents with S America catching water coming around S Africa sending it northward to the equator where it flows west into the Caribbean and between Florida and Cuba into the N Atlantic on to Europe. That conveyor belt will exist regardless of any ice sheets or global warming, its just a matter of how far north the warmer water can get before sinking and returning southward. If the Arctic is warmer, the current travels further north. But the gradual melting of the Greenland ice sheet will inhibit the northern extent of the gulfstream current, even slowing the current. This delays the migration of the gulfstream up into the Arctic long enough for the next ice age to take hold.
If not for the factors causing ice ages, it seems to me current conditions would eventually melt northern ice and the gulfstream would travel up into the Arctic bringing greater warmth to the northern latitudes all across the world. But that wont happen because just as the world warms up, the eccentricity of the earth's orbit increases and the axial tilt decreases so less sunlight hits the earth, especially at higher latitudes and the ice returns.
If we could warm the world enough to melt northern ice before the orbit forces the next ice advance, could we reduce the impact of ice ages? If we could "help" the gulfstream carry more, warmer water even further north toward the Arctic, would that help prevent or reduce the growth of ice sheets?
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