Introduction

The sixth as well as the fifth IPCC report on climate change [6–8] essentially confirm the statements of the fourth report from 2007. In particular, it is confirmed that global warming is man-made and the necessity to curb CO2 emissions quickly is emphasized more urgently than before, in order not to let the average temperature increase of the earth rise above 2 °C as a minimum target (2-degree limit). The Paris Agreement of 2017 recommends a stronger limit of 1.5-degrees-