Keeping global warming in the 1.5-2 degrees Celsius range could be much more difficult than previously thought, according to an article published in the journal Proceedings of the National Academy of Sciences (PNAS). An international team of scientists found that even if all the conditions of the Paris climate agreement are met, the average temperature on the planet will be 4-5 degrees Celsius higher than the pre-industrial level. As a result, the planet may turn into a "greenhouse", and a large number of regions will simply become uninhabitable.
The Paris Climate Agreement was signed in December 2015. It was joined by 195 countries, including Russia. States have agreed to take action to keep the average temperature on Earth from rising by more than two degrees Celsius by 2100. At the moment, the average temperature on Earth is about 1 degree Celsius above the pre-industrial level and increases by 0.17 degrees Celsius for each subsequent decade. Even if the temperature target is met, the Earth is still likely to become a greenhouse, according to lead author Will Steffen of the Australian National University.
“Greenhouse gas emissions are not the only factor contributing to global warming. Our research shows that human-induced global warming of 2 degrees Celsius, even if greenhouse gas emissions cease, could trigger other processes on Earth, often referred to as a "response", which ultimately lead to an even higher average temperature on the planet,”says Will Steffen.
"To avoid such a scenario, humanity must redirect its activities from purely operational to moderate management of the earth system."
According to scientists, due to human activities in nature, other irreversible processes occur that can contribute to further warming up of the atmosphere. This includes the melting of permafrost, the rise of methane from the ocean floor, a decrease in the amount of carbon absorbed by land and the ocean, an increase in the intensity of bacterial respiration in the oceans, a reduction in forest areas in the Amazon River basin, a reduction in snow cover in the Northern Hemisphere, and a decrease in ice masses in the Arctic in summer as well as shrinking polar ice sheets.
“All of these elements act like falling dominoes. One knuckle falls and it knocks over all the others. It will be very difficult or even impossible to stop the fall of a whole series. If the Earth turns into a "greenhouse", many regions will become simply uninhabitable, "adds co-author Johan Rockström of the Potsdam Institute for the Study of Climate Change.
Scientists argue that in order to minimize the impact, it is necessary not only to reduce gas emissions, but also to create natural reservoirs for storing carbon through forest planting, soil and biodiversity conservation. It is also necessary to develop new technologies to absorb carbon dioxide from the atmosphere and store it underground, experts say.
Researchers suggest that these processes will become irreversible when a certain planetary "stress threshold" is crossed. At the same time, experts are not yet ready to definitely answer the question of where the point of climatic equilibrium will be.
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