On Tuesday, June 1, President Donald Trump fulfilled yet another campaign promise by announcing that the US was withdrawing from the 2015 Paris climate agreement. The goal of the historic pledge signed by 195 countries is to curb the use of fossil fuels to ensure that average global temperatures do not increase more than 2°C (3.6°F) above pre-industrial levels. Environmentalists believe this is a critical threshold above which the planet could experience irreversible impacts, such as an unprecedented rise in sea levels and widespread plant and animal extinction.