Icecap Loss Estimate Cut by Half

Scientists found that icecap size varies according to corrections for deformations of the Earth’s crust.

AFP

Estimates of the rate of ice loss from Greenland and West Antarctica, one of the most worrying questions in the global warming debate, should be halved, according to Dutch and US scientists.

In the last two years, several teams have estimated Greenland is shedding roughly 230 gigatons of ice, or 230 billion tonnes, per year and West Antarctica around 132 gigatons annually.

Together, that would account for more than half of the annual three-millimetre (0.2 inch) yearly rise in sea levels, a pace that compares dramatically with 1.8mm (0.07 inches) annually in the early 1960s.

But, according to the new study, published in the September issue of the journal Nature Geoscience, the ice estimates fail to correct for a phenomenon known as glacial isostatic adjustment.

This is the term for the rebounding of Earth’s crust following the last Ice Age.

Glaciers that were kilometers (miles) thick smothered Antarctica and most of the northern hemisphere for tens of thousands of years, compressing the elastic crust beneath it with their titanic weight.

When the glaciers started to retreat around 20,000 years ago, the crust started to rebound, and is still doing so.

This movement, though, is not just a single vertical motion, lead researcher Bert Vermeersen of Delft Technical University, in the Netherlands, said in phone interview with AFP.

“A good analogy is that it’s like a mattress after someone has been sleeping on it all night,” he said.

The weight of the sleeper creates a hollow as the material compress downwards and outwards. When the person gets up, the mattress starts to recover. This movement, seen in close-up, is both upwards and downwards and also sideways, too, as the decompressed material expands outwards and pulls on adjacent stuffing.

Often ignored or considered a minor factor in previous research, post-glacial rebound turns out to be important, says the paper.

It looks at tiny changes in Earth’s gravitational field provided by two satellites since 2002, from GPS measurements on land, and from figures for sea floor pressure.

These revealed, among other things, that southern Greenland is in fact subsiding, as the crust beneath it is pulled by the post-glacial rebound from northern America.

With glacial isostatic adjustment modelled in, the loss from Greenland is put at 104 gigatons, plus or minus 23 gigatons, and 64 gigatons from West Antarctica, plus or minus 32 gigatons.

These variations show a large degree of uncertainty, but Vermeersen believes that even so a clearer picture is emerging on ice sheet loss.

“The corrections for deformations of the Earth’s crust have a considerable effect on the amount of ice that is estimated to be melting each year,” said Vermeersen, whose team worked with NASA’s Jet Propulsion Laboratory and the Netherlands Institute for Space Research.

“We have concluded that the Greenland and West Antarctica ice caps are melting at approximately half the speed originally predicted.”

If the figures for overall sea level rise are accurate, ice sheet loss would be contribute about 30 percent, rather than roughly half, to the total, said Vermeersen. The rest would come mainly from thermal expansion, meaning that as the sea warms it rises.

The debate is important because of fears that Earth’s biggest reservoirs of ice, capable of driving up ocean levels by many metres (feet) if lost, are melting much faster than global-warming scenarios had predicted.

In 2007, the UN’s Intergovernmental Panel on Climate Change (IPCC) predicted oceans would rise by 18-59 centimeters (7.2 and 23.6 inches) by 2100, a figure that at its upper range means vulnerable coastal cities would become swamped within a few generations.

The increase would depend on warming estimated at between 1.1 and 6.4 degrees Celsius (1.98-11.52 degrees Fahrenheit) this century, the IPCC said. It stressed, though, the uncertainties about ice sheet loss.

UN warns climate change could trigger ‘mega-disasters’

The same people who brought us Anthropogenic Global Warming, Climategate, Sustainability and the toxic Green Revolution now warn us about mega-disasters to come due to Climate Change.  Should we believe them?  Should we even pay attention to them?  Yes, but not for their science.  Even knowing all the history of the planet’s climate, they weren’t able -or did not want to- tell us the truth about the Earth’s state of affairs.  Can they be truthful about it now?  NO.  We should be concerned about their warnings because these same globalists are the owners of Laser Weapons and Weather modification technology to make any disaster happen.

AFP

Weather-related catastrophes brought about by climate change are increasing, the top UN humanitarian official said Sunday as he warned of the possibility of “mega-disasters”.

John Holmes, the UN Under-Secretary General for Humanitarian Affairs, said one of the biggest challenges facing the aid community was the problems stemming from changing weather patterns.

“When it comes meteorological disasters, weather-related disasters, then there is a trend upwards connected with climate change,” Holmes, who is in Australia for high-level talks on humanitarian aid, told AFP.

“The trend is there is terms of floods, and cyclones, and droughts.”

Holmes, who is the UN’s emergency relief coordinator, said it had been a tough year due to January’s devastating earthquake in Haiti, which killed more than 250,000 people.

He said while earthquakes, such as the 7.0-magnitude quake which levelled the Haitian capital Port-au-Prince, were random, weather-related natural disasters were increasing in number and scale.

“It’s partly the very obvious things like the number of cyclones and the intensity of the cyclones, and the amount of flooding,” he said.

“But is also in slightly more invisible ways — in Africa with drought spreading, desertification spreading.”

Holmes said officials were particularly concerned about places where a combination of factors — such as large populations, or likelihood of earthquake, or susceptibility to rising sea levels — made them more vulnerable.

“One of things we worry about is mega cities could produce, at some point, a mega disaster,” he said.

“Cities like Kathmandu for example, which sits on two earthquake faults, where a large earthquake will come along… and the results could be catastrophic.”

Holmes said while some countries were well-prepared for disaster — such as Chile which was hit with a massive 8.8-magnitude earthquake in February which left 520 people dead — others such as Haiti were less able to manage.

“That’s one of the reasons we want to focus on not just how we respond to disaster, we need to do that, but how you reduce the impact of those disasters before they happen,” Holmes said.

In Haiti, the situation remained serious, he said, with some 1.5 million people living in makeshift shelters and little prospect of this changing soon.

“There are real concerns about how vulnerable people still are, despite all the efforts that have been made,” he said.

Holmes said the need for humanitarian aid was rising faster than resources were available, particularly given the long-running conflicts in areas such as Sudan’s Darfur and the Democratic Republic of Congo.

At the same time, climate change would likely set in chain migration due to drought or rising sea levels or conflicts due to a scarcity of water or arable land in coming years and these would place more pressure on funds.

“So all these things are going to create more problems for us, and we’re really just coming to grips with what the consequences might be,” Holmes said.

“And you can construct some extremely scary scenarios for yourself without too much trouble.

“For example, about what the effect might be of glaciers melting in the Himalayas. Now we don’t quite know whether that’s happening, or will happen, or not. But if it did, what would the effect be on the major river systems of southern Asia?”

Holmes said while a decade ago, climate change was not on officials’ radars, “now it’s on everybody’s agenda.”

“Climate change for us is not some future indeterminate threat, it’s happening in front of our eyes,” he said. “We can see it.”