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Climate change: A warning from the recent Antarctic forests



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Jane Francis / BAS

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Posts from Pliocene: The warmest world that saw plants in the Antarctic interiors

Moving through the open rocks in the middle of Antarctica, you can find mummified branches of shrubs that grew up on the continent for about ninety million years ago.

This plant material can not be seen, but scientists say it should serve as a warning to the world about where climate change can take us if carbon emissions do not exceed.

The period of time is an epoch that geologists call pliocene, 2.6-5.3 million years ago. It was marked by temperatures that were considerably warmer than today, possibly 2-3 degrees around the world.

These were conditions that allowed the growth of plants, even in the middle of the White Continent.

Higher were also sea levels. As far as is unknown, but perhaps in the area of ​​1

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

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

In fact, Pliocene has recently been in the history of the Earth that air has had the same concentration of greenhouse gas.

And this tells you where we are going, if we do not seriously deal with the climate problem, warns Professor Martin Siegert of the Grantham Institute at Imperial College London.

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Media title Professor Jane Francis:

The temperatures currently may be lower than that of Pliocene, but this is just because there is a backlog in the system, he says. .

"If you put your stove home and set it at 200C, the pace of erature does not reach this level immediately, it will take a bit of time," he told reporters.

– Similarly, with the climate of the Earth. If you raise The level of CO2 at 400 ppm, it suddenly does not reach the balance overnight. It can take 300 years or so.

"So, the question to us: what is the state of equilibrium; What will the Earth's climate look like at 400 points per minute, all things are solved? "

Prof. Siegert was among the group of scientists gathered in London Wednesday for discussion of the Pliocene climate lessons

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

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T.Ronge / AWI

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

Many knowledge that we now have about the era comes from the ocean's siege. These dirt, drilled near the coast of Antarctica, contain fossil organisms whose geochemistry can be used to reconstruct ancient temperatures and the corresponding probable amount of ice on the planet.

If, as scientists suspect, the sea levels were 10-20 m higher in the Pliocene, this indicates that the glaciers should also look very different.

"The Greenland ice sheet is about 7 meters (the equivalent of the sea)." This was probably not the case, "said Professor Imperial Prof. Tina van de Fliedtt.

" In Antarctica we have a smaller Western Antarctic ice sheet, which is about 5 meters, then we have a big piece in Eastern Antarctica.There are certain parts of what people considered stable for a very long time.However, this type does not work with numbers.If we need more than 10 meters of sea level rise, we also need unstable East Antarctica. "

Ts e can definitely explain the presence of plants in the middle of the continent, where only lichens and mosses survive today

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Jane Francis / BAS

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These rocks containing fossil plants from Pliocene, located only 500 km from the South Pole

Professor Jane Francis, director of the British Antarctic survey, pulled out his rocky rocky shrub from rocks only 500 km from the South Pole.

"These are branches that are similar to the southern beech," she told BBC News. "I like to call them the remains of the last forests of Antarctica."

"They are probably Pliocene at the age. What we are looking at at the time when the glaciers retreated, and we were left with areas in front of those glaciers where small bushes could grow. It would not be a good place to live; it would be surrounded by tundra, but with sufficient sunshine in the summer, and temperatures (capable of rising) to about 5 ° C.

The key is unknown how much, how soon, how fast can Antarctica retreat in the modern world?

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It is unclear how fast Antarctica glaciers can react to a built-in warming of 400ppm

Perhaps very quickly, there is a response from Professor Rob DeContou of the University of Mass. Amherst.

He manages computer models that include physical processes in ice, which can lead to the rapid collapse of rocks at the front of the Antarctic glaciers that end in the ocean.

"Today we measure rising sea levels in millimeters per year. So, a little more than 3 mm a year now," he explained.

"But these new processes predict the potential for centimeters a year. But we are looking for geologists to guide our tariffs. It may take 10,000 years to get to 20m. We still have a lot of work to

For Professor Siegert, the need to control carbon emissions very quickly and then return the concentration is urgent.

"Can we limit the temperature rise to 1.5 degrees this century? Can we do this? It's possible," he says.

"We need to bring the level of CO2 to 40% from what they are today by 2030 or so. And then to zero by 2050, and then after that, it's a huge task, but it's possible."


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