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Low CO2 Levels Spurred Prehistoric Creation of Greenland Ice

Why cold hard facts of Greenland study could affect us all

Yorkshire Post (U.K.), Aug. 28, 2008

Until a few years ago Greenland wasn't a place high on most people's must-see list unless they happened to be a geologist, or fancied a spot of whale watching. But today, the world's largest island has become a testbed for scientists trying to understand the implications of climate change.

A new report, published today in the science journal, Nature, claims that changes in carbon dioxide levels in the atmosphere led to the creation of the Greenland ice-sheet, further evidence, experts claim, that carbon dioxide changes the nature of our planet.

The 12-month study, funded by the British Antarctic Survey, was led by scientists at
Leeds University and Bristol University.

Among them was Dr Alan Haywood, based at the
School of Earth and Environment, in Leeds.

"Given the issue of global warming and people wanting to know if the ice sheets are going to melt, we wanted to try and understand why the
Greenland ice sheet existed in the first place," he says.

Three million years ago,
Greenland was covered in grass and forest, and to find out why an ice-sheet formed, a team of climatologists and geologists used hi-tech climate and ice sheet models to test competing theories. These ranged from changes in ocean currents and the Earth's orbit, to the rising level of the Rocky Mountains and the potential impact of a permanent El Nino.

Scientists discovered that the overwhelming cause was a drop in carbon dioxide levels in the atmosphere.

"This is significant because it's the one thing we are changing in the atmosphere at the moment through the generation of greenhouse gases," says Dr Haywood.

"We are not saying in the next 10 or 20 years we expect the
Greenland ice sheet to melt. But it reinforces something we've suspected for a long time, that CO2 has the potential to have a very significant effect on this ice sheet."

Carbon dioxide levels are now approaching those that existed when
Greenland was ice-free, and have risen dramatically since the mid-18th century and the birth of the Industrial Revolution. Three million years ago, CO2 levels were just over 400 parts per million (ppm) before they dropped inexplicably by almost half, while today's levels are around 387 ppm and rising.

"What these findings tell us clearly and eloquently is that we're playing with the one thing that appears to have the largest impact on the
Greenland ice sheet."

But given the fact that
Greenland is largely unpopulated, why does it matter if the ice disappears?

"It would cause sea levels to rise by about six metres, which doesn't sound much, but a lot of big cities like
Tokyo, London, Miami and New Orleans are less than six metres above sea level, and the Thames Barrier certainly wasn't designed to deal with anything like this."

Dr Haywood says that although scientists cannot predict how quickly, or slowly, ice levels will change, they do know what causes this change, and CO2 is a key factor.

"You can't understand how something is going to behave until you know why it's there in the first place. So understanding what caused the ice sheet to form puts us in a much stronger position to say that future CO2 increases will have a significant impact."

However, other research the same team is currently working on suggests that the
Greenland ice sheet is less sensitive to carbon dioxide now than it was three million years ago. "This is something we should be glad about because it gives us more time to deal with the issue."

But he admits, too, that we are entering uncharted scientific territory. "The rate of CO2 increases we are seeing now are greater than anything we have seen in the geological record by some magnitude."

Which is why Dr Haywood believes the world needs to act sooner, rather than later.

"We need to establish a line that we don't cross even if there are no short-term repercussions.

"Is it ethical for a generation that recognises the dangers to then do nothing? I don't think history would look kindly on that. We have a responsibility to look after our planet and hopefully leave it in an even better condition for future generations."

The next step, he says, is to find out why carbon dioxide levels fell millions of years ago.

"We've found the bullet, now we have to find the smoking gun."

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