Climate Change to Continue to Year 3000

 Scientists have made dire predictions about the effects of climate change. They say the effects will continue until the year 3000 and will cause oceans to rise 13 feet. The calculations are based on a computer model derived from records for more than 300 glaciers.

Global warming may wipe out three-quarters of Europe's alpine glaciers by 2100 and hike sea levels by four meters (13 feet) by the year 3000 through melting the West Antarctic ice sheet, two studies published on Sunday said.

The research places the spotlight on two of the least understood aspects of climate change: how, when and where warming will affect glaciers on which many millions depend for their water, and the problems faced by generations in the far distant future.

The glacier study predicts that mountain glaciers and ice caps will shrink by 15-27 percent in volume terms on average by 2100.

"Ice loss on such a scale may have substantial impacts on regional hydrology and water availability," it warns.
Some regions will be far worse hit than others because of the altitude of their glaciers, the nature of the terrain and their susceptibility to localized warming.

New Zealand could lose 72 percent (between 65 and 79 percent) of its glaciers, and Europe's Alps 75 percent, meaning a range of between 60 and 90 percent. At the other end of the scale, glacial loss in Greenland is predicted at around eight percent and at some 10 percent in high-mountain Asia.
Meltwater will drive up world sea levels by an average of 12 centimeters (five inches) by 2100, says the study.

 This figure -- which does not include expansion by the oceans as they warm -- largely tallies with an estimate in the landmark Fourth Assessment Report by the UN's Intergovernmental Panel on Climate Change (IPCC) in 2007.

Geophysicists Valentina Radic and Regine Hock of the University of Alaska base these calculations on a computer model derived from records for more than 300 glaciers between 1961 and 2004.

The model factors in the middle-of-the-road "A1B" scenario for greenhouse-gas emissions, by which Earth's mean surface temperature would rise by 2.8 degrees Celsius (5.04 degrees Fahrenheit) during the 21st century.
The tool was then applied to 19 regions that contain all the world's glaciers and icecaps.

 But -- importantly -- it does not include the ice sheets of Antarctica and Greenland, where 99 percent of Earth's fresh water is locked up.
If either of these ice sheets were to melt significantly, sea levels could rise by an order of meters (many feet), drowning coastal cities.

That very scenario emerges in the second study, which focuses on the inertial effect of greenhouse gases. Carbon molecules emitted by fossil fuels and deforestation linger for many centuries in the atmosphere before breaking apart.

Even if all these emissions were stopped by 2100, the warming machine would continue to function for centuries to come, says the investigation.
It largely bases its forecast on the "A2" emissions scenario, which sees greater carbon pollution by 2100, stoking Earth's temperature by an average 3.4 C (6.1 F) by century's end.

 Warming of the middle depths of the Southern Ocean could unleash the "widespread collapse" of the West Antarctic ice sheet by the year 3000, it says.

"The inertia in intermediate and deep ocean currents driving into the southern Atlantic means those oceans are only now beginning to warm as a result of CO2 (carbon dioxide) emissions from the last century," said Shawn Marshall, a professor the University of Calgary in Canada.

"The simulation showed that warming will continue, rather than stop or reverse, on the thousand-year timescale." The two studies are published online by the journal Nature Geoscience.

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World's Sixth Mass Extinction May Be Soon

A western lowland gorilla resting against tree. The gorilla, like many other animals today, is endangered. Over the past 540 million years, there have been five mega extinction events. Mankind may be causing a sixth due to habitat loss, over-hunting, over-fishing and the spread of germs. Until human populations expanded, mammal extinctions were very rare.

Mankind may have unleashed the sixth known mass extinction in Earth's history, according to a paper released on Wednesday by the science journal Nature.

Over the past 540 million years, five mega-wipeouts of species have occurred through naturally-induced events.

But the new threat is man-made, inflicted by habitation loss, over-hunting, over-fishing, the spread of germs and viruses and introduced species, and by climate change caused by fossil-fuel greenhouse gases, says the study.

Evidence from fossils suggests that in the "Big Five" extinctions, at least 75 percent of all animal species were destroyed. Palaeobiologists at the University of California at Berkeley looked at the state of biodiversity today, using the world's mammal species as a barometer.

"It looks like modern extinction rates resemble mass extinction rates, even after setting a high bar for defining 'mass extinction," said researcher Anthony Barnosky.

This picture is supported by the outlook for mammals in the "critically endangered" and "currently threatened" categories of the Red List of biodiversity compiled by the International Union for Conservation of Nature (IUCN).

On the assumption that these species are wiped out and biodiversity loss continues unchecked, "the sixth mass extinction could arrive within as little as three to 22 centuries," said Barnosky.

Compared with nearly all the previous extinctions this would be fast-track.

Four of the "Big Five" events unfolded on scales estimated at hundreds of thousands to millions of years, inflicted in the main by naturally-caused global warming or cooling.

The most abrupt extinction came at the end of the Cretaceous, some 65 million years ago when a comet or asteroid slammed into the Yucatan peninsula, in modern-day Mexico, causing firestorms whose dust cooled the planet.An estimated 76 percent of species were killed, including the dinosaurs.

The authors admitted to weaknesses in the study. They acknowledged that the fossil record is far from complete, that mammals provide an imperfect benchmark of Earth's biodiversity and further work is needed to confirm their suspicions.But they described their estimates as conservative and warned a large-scale extinction would have an impact on a timescale beyond human imagining.

"Recovery of biodiversity will not occur on any timeframe meaningful to people," said the study.

"Evolution of new species typically takes at least hundreds of thousands of years, and recovery from mass extinction episodes probably occurs on timescales encompassing millions of years."

Even so, they stressed, there is room for hope.

"So far, only one to two percent of all species have gone gone extinct in the groups we can look at clearly, so by those numbers, it looks like we are not far down the road to extinction. We still have a lot of Earth's biota to save," Barnosky said.Even so, "it's very important to devote resources and legislation toward species conservation if we don't want to be the species whose activity caused a mass extinction." Asked for an independent comment, French biologist Gilles Boeuf, president of the Museum of Natural History in Paris, said the question of a new extinction was first raised in 2002.

So far, scientists have identified 1.9 million species, and between 16,000 and 18,000 new ones, essentially microscopic, are documented each year."At this rate, it will take us a thousand years to record all of Earth's biodiversity, which is probably between 15 and 30 million species" said Boeuf.

"But at the rate things are going, by the end of this century, we may well have wiped out half of them, especially in tropical forests and coral reefs."

Until mankind's big expansion some 500 years ago, mammal extinctions were very rare: on average, just two species died out every million years. But in the last five centuries, at least 80 out of 5,570 mammal species have bitten the dust, providing a clear warning of the peril to biodiversity.

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