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The results of a survey are based on observations from three warm periods over the last 3.5 million years, when the world was warmer by 0.5 to 2 ° C than the pre-industrial temperatures of the 19th century.
Global warming could be twice as hot as predicted by scientific models, and sea level could rise by six meters or more, warned a group of researchers from 17 countries.
The results of a survey are based on observational evidence of three warm periods in the last 3.5 million years, when the world was 0.5 to 2 degrees C warmer than the temperatures pre-industrial 19th century.
The data was recently published in the journal "Nature Geoscience" and distributed by the University of New South Wales (UNSW) in Australia
Professor at the University of Bern (Switzerland) and author The climate model, Hubertus Fischer, explained that observations of warming periods in the past suggest that it is increasing in the long run beyond projections.
To obtain their results, the researchers analyzed three of the best documented warm periods. , the thermal maximum of the Holocene (5000-9000 years ago), the last warm interglacial period (129.000-116.000 years) and the average warm period of the Pliocene (3.3-3 million years ago). The first two periods were caused by predictable changes in the Earth 's orbit, while the average Pliocene event was the result of carbon dioxide concentrations in the atmosphere of 350-450 ppm ( parts per million), almost the same as in Currently,
Therefore, combining a wide range of measurements of ice cores, sediment layers, fossil recordings, dating using atomic isotopes and a series of D & D Other established palaeoclimatic methods, researchers have reconstructed the impact of these climate changes.
From these data, they consider that today the planet is heating up much faster than any of these periods, since carbon dioxide emissions caused by humans continue to grow. even if emissions stop, it would take centuries or millennia to reach equilibrium.
The changes on Earth in these past conditions were profound: there were major retreats of the Antarctic ice caps and Greenland, and as a result, the sea level rose by at least six meters; marine plankton beaches have changed by reorganizing entire marine ecosystems.
The co-author of the Oregon State University study, Alan Mix, said that even with 2 ° C warming, and probably only 1.5 ° C, the Earth system is deep .
"We can expect sea-level rise to be irreversible for millennia, affecting much of the world's population, infrastructure and economic activity," he said. He underlines. these significant changes observed are generally underestimated in short-term climate model projections.
Katrin Meissner, co-author and director of the UNSW study, pointed out that climate models seem reliable for small changes, such as: low emission scenarios over short periods, for example in the following decades up to 39, in 2100.
He clarified that this investigation is a call to action uar: "tells us that if the leaders of today do not tackle urgently our emissions, global warming will bring profound changes to our planet and our way of life, not only for this century but also beyond "(1965, p., id) {
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