Ocean floor deposits and model calculations have confirmed that in the past 3 million years, the global mean temperature has never been more than two degrees above pre-industrial levels, with fluctuating CO2 levels in the atmosphere. Since the beginning of industrialization, more CO2 has accumulated in the atmosphere through the burning of coal, oil and gas than probably ever before in the past 3 million years. Thus, in our current century, there is real threat that without effective climate policy the 2-degree limit of global warming will be breached for the first time – with far-reaching consequences.

Over the past century, global greenhouse gas emissions have led to a sharp increase in the number of bat species in the southern Chinese Yunnan province. Bats in this area have been suggested as the original carriers of SARS-CoV-2, the virus that causes Covid-19. Scientists from Cambridge, Potsdam and Hawaii showed in a study that climate change caused shifts in the natural vegetation of the region, which allowed c. 40 bat species, carrying around 100 coronaviruses, to expand into newly suitable habitat. This process would have likely created new opportunities for viruses to be transmitted or evolve, potentially facilitating the eventual spill-over to humans. In this way, climate change may have played an important role in the outbreak of SARS-CoV-2.

Economic growth goes down when the number of wet days and days with extreme rainfall go up. PIK researchers found that statistically 10 more wet days in a year reduce economic growth of a region by 1%. Rich countries are most severely affected, especially the manufacturing and service sectors. The data analysis of more than 1.500 regions over the past 40 years shows a clear connection and suggests that a rising number of daily rainfall extremes, caused by human-made climate change, will harm the global economy.