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Geneva, 9 Jul (PTI) The Earth could end up being twice as hot as predicted by climate models, even if the world reaches the goal of limiting global warming to less than two degrees Celsius, according to a study.
The study, published in the journal Nature Geoscience, showed that sea levels can reach six meters or more even if the climatic targets of Paris are met.
The results are based on observations of three warm periods over the course of 3.5 million years. The world was 0.5 to 2 degrees Celsius warmer than the pre-industrial temperatures of the 19th century.
Research has also revealed how large areas of polar ice caps could collapse and significant changes in ecosystems could see the Sahara Desert become green. the edges of tropical forests are transformed into savannah dominated by fire.
"Observations from past warm-up periods suggest that a number of amplifying mechanisms, which are poorly represented in climate models, increase long-term warming." Hubertus Fischer of the University of Bern in Switzerland
"This suggests that the carbon budget to avoid the 2 degrees Celsius of global warming could be much lower than expected, leaving very little room for error to reach Paris. To get their results, the researchers examined three of the best-documented warm periods, the Holocene thermal maximum (5,000-9,000 years ago), the last interglacial period (129,000 to 116,000). The mid-Pliocene warm period (3.3-3 million years)
The warming of the first two periods was caused by predictable changes in the Earth's orbit, while the middle of the Pliocene was the result of atmospheric concentrations of carbon dioxide that were 350 to 450 ppm – a bit like today
Combining a wide range of measurements of ice cores, sediment layers, fossils, of dating using atomic isotopes and a host of other established methods of paleoclimate, the researcher s together the impact of these climatic changes.
In combination, these periods give a strong evidence of the l '. appearance of a warmer Earth once the climate stabilized. In contrast, today, our planet is warming much faster than any of these times, as anthropogenic emissions of carbon dioxide continue to grow.
Even if our emissions ceased today, it would take centuries or millennia to reach equilibrium. Under these past conditions, the Earth was plunged in deep conditions: the Antarctic and Greenland ice sheets were in considerable numbers and, as a result, the sea level had risen 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." We can expect sea level rise become irresistible for millennia, affecting a large part of the world's population, infrastructure and economic activity ", said Mix
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