claim: The consequences of climate change become increasingly bad after each additional degree of warming, with the consequences of 2°C being quite damaging and the consequences of 4°C being potentially catastrophic.
evidence: It is a major aspect of climate change, and has been demonstrated by the instrumental temperature record which shows global warming of around 1 °C since the pre-industrial period, although the bulk of this ( 0.9°C ) has occurred since 1970.