Many speculate what would happen to the U. S.’s pledges to curb greenhouse gas emissions after Donald J. Trump takes control of the White House. The U. S. promised not only to cut its own emissions through its Intended Nationally Determined Contribution (INDC) but to help poor countries under the Paris Agreement. Unfortunately, the President-elect has openly vowed to leave this landmark deal, which intends to limit the global temerature increase to 2 degrees Celsius. So, what if the U. S. cannot meet, or even abandon, the INDC? Alternatively, if it somehow manages to deliver its promise, does it mean the worst-case climate scenario averted?
Here, two journal articles will be discussed to understand the possible future developments in the next several years in a more quantitative fashion. Both published by Nature Climate Change, these articles examine how American climate policies will bring down GHG emissions, and how the results can vary in a different time frame.
“Assessment of the climate commitments and additional mitigation policies of the United States (Greenblatt and Wei, September 2016)” projects the GHG emissions reductions by modeling a number of Federal and State policies–including the Clean Power Plan (both final rule and enhanced versions), California’s SB350, EPA’s SNAP fuel phase-out, strengthened building codes, and voluntary manure management. The authors categorize the policies into three groups, A, B and C, to encompass establlished, proposed and voluntary measures, to see the different paths of emission levels. According to the results, there is a considerable gap between the INDC goals, 26 to 28 percent reductions below 2005 levels by 2025, and possible accomplishments through policy measures. Despite the significant uncertainties for historical and projected baseline, the conclusion is unequivocal: the gap narrows as policy gets more aggressive, moving along from the set A, B, to C, and additional measures are needed to close it.
Let us say these policies will be taken eventually, but not just now. What if the Administration following the next one implement all these measures, in 8 years from now? “Delays in U. S. mitigation could rule out Paris targets (Sanderson and Knutti, December 2016)” quantifies the effects of such temporal shift of the U. S.’s carbon policy. The main problem is that the emission levels do not stay the same during the 8 years, but they are likely to increase. This is not only because the coal industry will get more support from the coming Administration, but also there will be a significant cut in the investment in clean energy and carbon removal technology. According to the authors, the consequences are grisly in quantitative terms: if the U. S. withdraws its commitments and the rest of the world follows suit, cumulative emissions can almost double over the next century. The global CO2 reduction rate should be 2.4 percent per year if we start now, but it jumps to 4.2 percent if we postpone for 8 years. Undeniably, only immediate action can achieve the Paris targets.
Of course, it is not that one person can change the policy landscape alltogether. A New York Times article  suggests that Mr. Trump will have less control over the U. S. climate change policy, considering intrinsic limitation of executive power and market incentives that favors natural gas over coal. However, it is equally difficult to make a sloth move as to calm a roaring lion. As the article excellently puts it, the problem is “what he will not to, rather than what he might do.”
 Justin Gillis, January 2, 2017. Weak Federal Powers Could Limit Trump’s Climate-Policy Rollback. The New York Times.
Featured image source: Stanford Woods Institute for the Environment