Robbie Andrew

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Two or Three Degrees: Emissions and Global Temperature Impacts


Abstract

Carbon dioxide emissions from human activities have grown substantially over the past decade, reaching about 40 Gt CO2 per year in 2013 and some 2,000 Gt of cumulative CO2 since 1870. Very high mitigation rates and sustained reductions in greenhouse gases are now required to have any chance of keeping global tempera- tures from rising less than 2░C compared to preindus- trial levels. To date, however, such aggressive mitigation is not consistent with observed mitigation over the past 25 years or with current national emission reduction targets. Keeping global warming below 2░C also implies that the majority of proven fossil fuel reserves will stay in the ground, unless CCS techniques-unproven at the necessary scale-are rapidly implemented.

Despite all the important global policy discussions to keep global temperature increases below 2░C, few people realize how quickly the world is approaching the cumulative emission threshold for an increase of 3░C. If global CO2 emissions continue to grow at the annual rate of 2 percent observed for the past 15 years, increases of 3░C could be the reality only 30 years from now.

Stronger mitigation efforts are needed to reduce the rate of climate change, and adaptation policies are, and will be, needed to cope with the unavoidable climate impacts.

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