Global warming: towards an increase in the level of the oceans

Two new studies, published in the journal Science on March 24, confirm the impact of global warming on sea level rise.

Rely on the climates of the past ...
To get an idea of ​​the likely consequences of global warming on sea level rise, researchers from the National Center for Atmospheric Research (NCAR) and the University of Arizona simulated computationally the last prolonged period of warming 130 years ago. The oceans were then at least six meters above their current level.

Glaciologist Bette Otto-Bliesner of NCAR and his colleague Jonathan Overpeck of the University of Arizona, drew on paleoclimatic data, particularly from fossilized corals and ice cores.
Bette Otto-Bliesner points out that "the ice caps at the poles have already melted in the distant past causing the sea level to rise sharply with temperatures which were then not much higher than those of today". This is why the comparison seems interesting.

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... to predict our future
Both studies show that with the current and sustained increase in the concentration of greenhouse gases in the atmosphere, summer temperatures could rise in the Arctic by 3 to 5 ° C by the end of the century. .
In fact, scientists from the National Snow and Ice Data Center (NSDIC) noted in a study published at the end of 2005 that, over the past four years, the average temperature at the surface of the Arctic Ocean was, between January and August 2005, 2 to 3 degrees Celsius higher than in the last fifty years.

At the planetary level, we rather expect, in the most optimistic and desirable scenarios, a 2 ° C increase in the average temperature on Earth by 2100; the arctic would then experience, with a surplus of 1 to 3 ° C, climatic conditions that prevailed 130 years ago, the last warm period between the previous one and the last ice age.
Note that this previous warming was then the consequence of a variation in the axis of rotation and the Earth's orbit, and not of an increase in the greenhouse gas content.

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