Earth can be twice as hot as expected

The Earth could end up being twice as hot as predicted by climate models, although the world's goal is to limit global warming to less than two degrees Celsius, according to a study. The study, published in the journal Nature Geoscience, has shown that sea levels can rise six meters or more even if the Paris climate goals are met. The results are based on observational evidence from three warm periods over the past 3.5 million years when the world was 0.5 to 2 degrees Celsius warmer than the pre-industrial temperatures of the 19th century.

The research also revealed how large areas of the polar ice caps could collapse and significant changes in ecosystems could see the Sahara Desert become green and the edges of the tropical forests turn into savannah-dominated savannahs. fire. "Observations from past warm-ups suggest that a number of amplifying mechanisms, poorly represented in climate models, increase long-term warming beyond the projections of the climate model," says Hubertus Fischer of the US. University of Bern in Switzerland. the carbon budget to avoid 2 degrees Celsius of global warming could be much lower than expected, leaving very little room for error to achieve the Paris targets, "said Fischer. To obtain their results, the researchers examined three of the best-documented warm periods, the Holocene thermal maximum (5,000-9,000 years), the last interglacial (129,000-116,000 years), and the warm period Pliocene mid-point (3.3-

Warming of the first two periods was caused by predictable changes in the Earth's orbit, while the mid-Pliocene event was the result of atmospheric concentrations carbon dioxide from 350 to 450 ppm, which is about today, by combining a wide range of measurements from ice cores, sediment layers, fossils, dating, and so on. With the help of atomic isotopes and a host of other established paleoclimatic methods, researchers have reconstructed the impact of these climate changes

. 39, a warmer Earth once the climate s On the other hand, today, our planet is heating up much faster than any of these times, as human-caused carbon dioxide emissions continue to grow. Even if our emissions ceased today, it would take centuries or millennia to reach equilibrium.

The changes in the Earth under these past conditions were profound – there were substantial withdrawals of the ice caps from Antarctica and Greenland and as a result the sea level increased by at least six meters; marine plankton ranges have been reorganized to reorganize entire marine ecosystems; the Sahara became greener and forest species moved 200 km to the poles, as did the tundra; High altitude species declined, temperate tropical forests were reduced and in Mediterranean areas fire-dominated vegetation dominated.

"Even with only 2 degrees Celsius of warming – and potentially only 1.5 degrees Celsius – the significant impacts on the Earth's system are profound," said Alan Mix of Oregon State University in the United States. We can expect sea level rise to become irrepressible for millennia, affecting much of the world's population, infrastructure, and economic activity, "said Mr. Mix.