Prospects for the Climate


Climate change has made the news recently with the announcement that the EPA will require a 30 percent reduction (from 2005 levels) in carbon dioxide emissions from U.S. power plants by 2030. This certainly is a major policy change in the sense that it is the first significant action that the United States has taken to reduce greenhouse gas emissions – but how much effect will it really have? 

First, what does a 30 percent reduction from 2005 levels mean? Figure 1 shows U.S. carbon dioxide emissions from the burning of fossil fuels since 2005. In 2005, emissions were around 6 billion metric tons. In 2008 they started to fall, for the most part due to the recession and the subsequent decrease in energy use, but also somewhat due to increasing efficiency and the substitution of natural gas for coal. But, since most of this trend was due to a shrinking economy, we should expect that as growth resumes the general trend will be upward, and in fact emissions rose by about 2.4 percent between 2012 and 2013.

energy related carbon dioxide emissions

A 30 percent emissions reduction from 2005 levels would put us at about 4.2 billion tons per year. Due to the decrease in emissions between 2007 and 2012, we are currently emitting about 5.5 billion tons, meaning that we are already about 28 percent of the way to the goal. This fact has been repeated many times in media coverage of these new regulations, usually with the implication that we’re well on our way. This is not quite the case – despite the short term fall, the trend in emissions is still up (emissions are projected to rise in 2014).

The proposed reductions will require significant action from many states, especially those that rely heavily on coal power plants. But there is reason to be optimistic: past emission regulations in the United States have been highly successful, most notably the virtual elimination of ozone-depleting substances and the reduction of pollutants that cause acid rain. So, assuming the emissions targets are met by 2030, the U.S. will have reduced its emissions by about 1.8 billion tons. This is about 5 percent of current global emissions. Given the extremely rapid global increase in emissions (Figure 2), no doubt the percentage will be lower by 2030. So the proposed reductions are unfortunately not going to save the climate.

trends in global emissions

The hope of course is that the U.S. regulations will provide some credibility to the next major round of climate negotiations to be held in 2015 in Paris. A global solution is essential, as emissions are skyrocketing in the developing world and leaving the U.S. and Europe with less direct control over the future of the atmosphere. We are currently following the highest emissions scenario commonly studied in climate science, leading us towards a catastrophic 3-5 degrees Celsius of global warming by 2100.

We of course must be optimistic about the future and our ability to deal with serious long-term problems, and we should keep in mind that there are levels of failure; 2 degrees Celsius of warming is better than 3, but 3 degrees is much better than 4 or 5. So just because it is looking increasingly unlikely that we will meet the somewhat arbitrary target of 2 degrees does not mean that we should give up on the problem. But it does mean that we must be realistic about the climate risks we face. We must focus not only on the theoretical best case, where emissions reductions are dramatic, but on the political and economic reality that we find ourselves in.

The fight against climate change is a war, not a battle, and it will likely be the defining issue for the next century. For me, the source of hope is that transformational economic change is the rule, not the exception. Think of the world in 1914 – we’ve come a long way in 100 years. The future of the climate will be a balancing act, with global warming and environmental degradation tipping us in one direction, but economic growth and technological advancement leaning in the other. The question is, which will win? And, as of now, that question is entirely in our control. 



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