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Climate change: Alert from the latest Antarctic forests



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Image of the Pliocene: A warmer world that saw the plants continue in the Antarctic interior

Climbs the open rocks in the middle of Antarctica and it is possible to find the mummified branches of shrubs that grew on the continent about five million years ago.

This plant material can not be looked at much, but scientists say it should serve as a warning to the world where climate change can take us if carbon emissions remain unnoticed.

The period of time is an age that geologists call Pliocene 2.6-5.3 million years ago. It was marked by temperatures that were significantly warmer than today, perhaps 2-3 degrees globally. These were conditions that allowed the growth of plants even in the middle of the White continent.

The higher were also sea levels. Not sure how much, but probably in the area of ​​1

0-20 m above the surface of the modern ocean.

What is really important is that the amount of carbon dioxide in the atmosphere is very similar to what is today – about 400 molecules of CO2 per million molecules of air.

Indeed, Pliocene was the last time in Earth's history that the air carried the same concentration of greenhouse gas. We do not take the climate problem seriously, warns Prof. Martin Siegert of the Grantham Institute at Imperial College London.

Media coverage Prof.

Temperatures can now be lower than in the pliocene but this is only because there is a delay in the system, he says. at home and set it at 200C, temp erature does not reach this level immediately; it takes a little time, "he told reporters

" It's the same with Earth's climate. If you increase the CO2 level to 400 parts per million, it will not suddenly reach equilibrium overnight. It will take even 300 years or something.

"So the question to us is: what is the equilibrium state, what will be the Earth's climate with 400ppm, all things settled?"

Prof Seigger is among a group of scientists who meet in London on Wednesday to discuss the Pliocene climate lessons.

These experts want to see much more research on the parallels between then and now.

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Image Title: Prof van De Flierdt (left): Much of what we know right now comes from ocean sediments

Many of the knowledge we currently have of the epoch comes from ocean sediments. This mud, drilled off the shores of Antarctica, contains fossil organisms whose geochemistry can be used to restore ancient temperatures and the corresponding possible volume of ice on the planet.

If, as scientists suspect, the sea levels were 10-20 meters higher in the pliocene, it shows that ice sheets should also have looked very different.

"Greenland's ice sheet has about 7 meters (equivalent to seawater), and it's probably gone," said professor Emperor Tina van de Fleurde.

"In Antarctica, we have a smaller Western Antarctic ice sheet holds about 5 meters. This is probably also gone. "then we have a big piece in Eastern Antarctica, there are parts of what people think is stable for a very long time but this kind does not work with the numbers If we need more than 10 meters of sea level rise, to be also unstable in Eastern Antarctica

This could certainly explain the presence of plants in the middle of the continent where only lichens and mosses can survive today

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Jane Francis / BAS

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These rocks that contain the dig My plants from the Pliocene were only 500 kilometers from the South Pole

Jane Francis, director of the British Antarctic Research, pulled out its fossil rock bush just 500 km from the South Pole.

"These are branches similar to southern beech," she told BBC News. "I like to call them the remains of the last forests of Antarctica. What we observe is the time when the glaciers retreated, and we have areas in front of those glaciers where small shrubs can grow. It would not be a nice place to live; this would be a tundra environment but with enough sun in the summer and temperatures (may rise) to about 5 degrees. "

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Key words: how much, how fast can it withdraw Antarctica in the modern era, 19659005] It's not clear how quickly Antarctic glaciers can react to warming at 400ppm

Probably very fast is the answer of Prof. Rob DeConto of the University of Massachusetts-Amherst.

He runs computer models that involve physical processes in the ice that can lead to a rapid collapse of rocks in front of Antarctic glaciers ending in the ocean.

"Today, we measure the sea level rise in millimeters per year, so just over 3mm per year now," he explained. "But these new processes imply a potential for centimeters per year. But we are looking for geologists to guide prices. It may take 10,000 years to reach 20m. We still have a lot of work to do

For Prof. Sieger, it is imperative to control the carbon emissions very quickly and then to reverse the concentration.

"Can we limit the temperature rise to 1.5 degrees this century? Can we do that?" He says.

"We have to bring CO2 levels to 40% of what they are today by 2030 or so, and then to zero by 2050, and then negative after that." This is a huge undertaking, but it is possible.


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