If the polar ice caps continue to melt, forests continue to be decimated and greenhouse gas emissions continue to break yearly records, the Earth will reach its own breaking point. A shift that could occur "in just a few decades," warned scientists in the National Academy of Sciences Scientific Journal (PNAS).
According to them, passing this threshold means, "a temperature of 4° C to 5° C higher than the pre-industrial period and sea levels 10 to 60 meters higher than today". “An Earth oven is probably uncontrollable and dangerous for many,” according to findings from scientists at Copenhagen University, the Australian National University and the Potsdam Research Institute on the effects of climate change in Germany.
Unprecedented rise in temperatures
The rivers would overflow, hurricanes would wreak havoc on the coasts and coral reefs would disappear, all before the end of this century, if not earlier. Global average temperatures would exceed those of any interglacial period in 1.2 million years.
The melting of the polar ice caps alone would cause a very significant rise in ocean levels, engulfing coastal regions where hundreds of millions of people live. "Places on Earth will become uninhabitable if the "Baking Earth" becomes a reality," warns Johan Rockström, director of the Stockholm Resilience Centre.
The researchers suggest that the breaking point could be reached when the Earth's temperature is 2° C warmer than the pre-industrial era. It is already one degree high and continues to grow at a rate of 0.17 degrees per decade.
Point of no return
"A 2° C warming could activate important tipping elements, raising the temperature further to activate other tipping elements in a domino-like cascade that could take the Earth System to even higher temperatures," warns the report.
This study used previous scientific work on the Earth's breaking points. The researchers looked at distant times, such as the Pliocene era five million years ago, when the level of CO² in the atmosphere was 400 parts per million (ppm), as it is today.
During the Cretaceous period - the dinosaur era - some 100 million years ago, CO² even reached 1,000 ppm largely because of volcanic activity. Determining that a rise of 2° C is a point of no return is "new," according to Martin Siegert, co-director of London's Grantham Research Institute on Climate Change, who was not involved in the study.
It is necessary to immediately change the way of life to protect the Earth, warned the researchers, explaining that fossil fuels should be replaced by low (or not-existent) CO² emitting sources.
They also advocated for better soil management, better farming practices, land and coastal protection, CO² capture techniques, tree planting and an end to deforestation.
But even if greenhouse gas emissions cease, the current warming trend could trigger other system conditions - or feedbacks - and cause temperatures to rise even further. These processes include the melting of permafrost, deforestation, lack of snow caps in the northern hemisphere, pack ice and polar ice caps.
Writing for AFP