New evidence shows that rising CO2 preceded the end of the last ice age.

Rising CO2 Levels Linked to Global Warming During Last Deglaciation

...the global greenhouse effect had an important role in driving up global temperatures and bringing the planet out of the last Ice Age...

Here is what the researchers think happened.

Small changes in Earth's orbit around the sun affected the amount of sunlight striking the northern hemisphere, melting ice sheets that covered Canada and Europe. That fresh water flowed off of the continent into the Atlantic Ocean, where it formed a lid over the sinking end of the Atlantic Meridional Overturning Circulation -- a part of a global network of currents that brings warm water up from the tropics and today keeps Europe temperate despite its high latitudes.

The ocean circulation warms the northern hemisphere at the expense of the south, the researchers say, but when the fresh water draining off the continent at the end of the last Ice Age entered the North Atlantic, it essentially put the brakes on the current and disrupted the delivery of heat to the northern latitudes.

"When the heat transport stops, it cools the north and heat builds up in the Southern Hemisphere," Shakun said. "The Antarctic would have warmed rapidly, much faster than the time it takes to get CO2 out of the deep sea, where it was likely stored.

"The warming of the Southern Ocean may have shifted the winds as well as melted sea ice, and eventually drawn the CO2 out of the deep water, and released it into the atmosphere," Shakun said. "That, in turn, would have amplified warming on a global scale."

The question now, the researchers say, is how human-generated carbon dioxide will affect the planet when there isn't an ice age.

"CO2 was a big part of bringing the world out of the last Ice Age," Shakun said, "and it took about 10,000 years to do it. Now CO2 levels are rising again, but this time an equivalent increase in CO2 has occurred in only about 200 years, and there are clear signs that the planet is already beginning to respond."

Since we know that increasing fresh water has been entering the North Atlantic, this makes me wonder if our climate models overlook the Antarctic heating effects from slowed Atlantic Meridional Overturning Circulation and subsequent release of deep stored CO2 from ocean basins from Southern Ocean warming. Climate Destabilization of The Global Ocean Conveyor Belt might turn out to be trickier than we first thought.

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Replies to This Discussion

Effects of Rising Atmospheric Concentrations of Carbon Dioxide on Plants

Changes taking place on glacial melting and thinning of ice has already been demonstrated. There have been reports of changing acidity of oceans, changes in flora and fauna patterns exist. 

We need to take a serious look at all these and more pieces of evidence and come to individual conclusions without the influence of money from energy sources. There are things one can do by one self, and ways to join with others to get the facts, make some sound decisions, and take some action. Information is available and easy to access. 


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