Two years ago, I co-led an analysis of several key climate-change-related risks facing the United States. Our team used state-of-the-art climate and economic models to assess multiple scenarios for the current century.
These scenarios, developed by the international climate modeling community, include a high-emissions future with expanded fossil fuel use and a low-emissions future in which, consistent with the aspirations of the Paris agreement, emissions go to zero in the second half of this century. Comparing the highest and lowest scenarios – let’s call them the Trump Trajectory and the Paris Path – provides a sense of the risks Donald Trump’s energy policy poses to our country and the planet.
Using the high scenario as a proxy for Trump’s policy, what changes could we expect?
Carbon dioxide concentrations in Earth’s atmosphere will average about 404 parts per million (ppm) this year. While the Paris Path would keep them from rising above 450 ppm, the Trump Trajectory would elevate them over 550 ppm in the 2050s and – if policies consistent with rapid expansion of fossil fuel production were maintained – over 900 ppm in the 2090s.
By the middle of the century, climate models indicate that global mean temperature would likely be about 0.5°-1.6°F warmer than today under the Paris Path, but 1.6-3.1°F warmer under the Trump Trajectory. The models also show that, by the last two decades of this century, temperatures would have stabilized under the Paris Path, while the Trump Trajectory would likely be about 4.4-8.5°F warmer.
Rasmussen et al., 2016, Author provided