The IPCC document, which has been analyzing for the United Nations since 1988 the effects of climate change on the planet, indicates, for example, that mountain and polar glaciers will continue to melt for decades or even centuries, even reducing emissions. “The report is a reality bath. Now we have a much clearer vision of the past, present and future climate, something essential to understand where we are going, what we can do, and how we should prepare ”, highlighted when presenting the report the co-chair of the group of experts that has prepared it, Valérie Mason-Delmotte.
The document also foresees irreversible changes on the scale of thousands of years in the temperature, acidification and deoxygenation of the oceans. On the other hand, it predicts that the sea level will continue to rise irretrievably, between 28 and 55 centimeters at the end of the century with respect to current levels, even achieving net zero emissions. “For decades the IPCC has warned us of the dangers of global warming, the world listened, but did not act with the enough forcefulness, and as a result the problem is here and no one is safe ”, underlined the executive director of the UN Environment Program, Inger Andersen.
The hottest world in the last two millennia
The report assures that the human being has had an “undeniable” role in the warming of the atmosphere, the ocean and the soil, leading the world to a rise in temperatures that has not been compared in the last 2,000 years. The study, which takes advantage of improvements in paleoclimatic research, shows that the current temperature increase is comparable to what is considered the warmest period of the last 100,000 years, which occurred 6,500 years ago (the so-called Holocene climatic maximum).
“It is indisputable that human activities have caused climate change and are causing the extreme weather events are more frequent and serious, affecting all regions of the planet ”, highlighted the president of the IPCC, Hyesong Lee. “Using a sports simile, the atmosphere is ‘doped’, and we now suffer these phenomena more frequently, as we have recently seen with the fires in Greece and California, or the floods in China and Europe,” added the Secretary General of the Organization. World Meteorological Service (WMO), Petteri Taalas.
Current changes in the climate are “unprecedented” in recent centuries and even millennia, say the scientists authors of the report. For example, according to IPCC experts, the current concentration in the atmosphere of carbon dioxide, the main greenhouse gas, exceeds 410 particles per million, the highest in the last two million years.
Experts calculate in the report that if the current rate of greenhouse gas emissions is maintained, the global temperature will rise 2.7 degrees by the end of the century compared to the average of the pre-industrial era (1850-1900).
This increase, which would also entail greater extreme weather events such as droughts, floods and heat waves, would be far from the goal of less than 2 degrees set by the Paris Agreement, which even called for limiting this rise to 1.5 degrees Celsius. The new report from the main institution that studies the climate change, delayed several months due to the covid-19 pandemic, considers five scenarios, depending on the level of emissions that is reached.
Maintaining the current situation, in which the global temperature is on average 1.1 degrees higher than in the pre-industrial period (1850-1900), would not be enough: scientists predict that this would reach a rise of 1.5 degrees in 2040, 2 degrees in 2060 and 2.7 in 2100.
Four more degrees, catastrophic scenario
In the most pessimistic scenario, where emissions of carbon dioxide and other greenhouse gases will double in the middle of the century, the increase could reach catastrophic levels of around 4 degrees in 2100, warns the report.
Each degree of increase could mean 7% more precipitation in the world, leading to an increase in storms, floods and other natural disasters. Extreme heat waves, which in pre-industrial times occurred approximately once a decade and currently occur 2.3 times, could multiply up to 9.4 times (almost one per year) in a scenario with 4 degrees warmer. On the contrary, in the most optimal hypothesis considered by the report, the one in which carbon neutrality (net zero emissions) is reached by mid-century, the temperature increase would be 1.5 degrees in 2040, 1.6 degrees in 2060 and it would even drop to 1.4 degrees by the end of the century. The study, prepared by 234 authors from 66 countries, recognizes that the emission reduction It would have no discernible effect on global temperature for about two decades, although the benefits in air pollution would be noticeable sooner, in a matter of a few years.