In the new report, released on 9 August, the IPCC considers five scenarios, depending upon the level of emissions achieved.
Maintaining the current situation, in which the global temperature is, on average, 1.1 degrees higher than in the pre-industrial period (1850-1900): scientists predict that, an increase of 1.5 degrees by 2040, 2 degrees by 2060, and 2.7 degrees by 2100.
This increase, which would also lead to more extreme weather events such as droughts, floods and heat waves, is far from the goal of reducing it to less than 2 degrees, set in the Paris Agreement, which fixes emission reduction of greenhouse gases from 2020, imposing a limit of 1.5 degrees centigrade as a goal.
In the worst case scenario, in which carbon dioxide and other greenhouse gas emissions would double by mid-century, the increase could reach catastrophic levels, around 4 degrees in 2100.
Each degree of increase predicts about seven percent more precipitation worldwide, which could lead to an increase in storms, floods and other natural disasters, warns the IPCC.
Extreme heat waves, which in pre-industrial times happened approximately once a decade and currently occur 2.3 times, can multiply up to 9.4 times per decade (almost one per year) in the scenario with more than 4 degrees of temperature.
On the other hand, in the best hypothesis considered by the experts, in which carbon neutrality (zero emissions) is reached in half of the century, the temperature increase would be 1.5 degrees in 2040, 1.6 degrees in 2060 and decrease to 1 .4 degrees at the end of the century.
The study by the main organization that studies climate change, prepared by 234 authors from 66 countries, was the first to be reviewed and approved by videoconference.
Experts recognize that emission reductions will have no visible effects on global temperature until a few decades have passed, although the benefits for reducing air pollution will start to show in just a few years.