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Better Science and a Worse Outlook: The Need for U.S. Leadership on Climate Change

Joshua P. Meltzer and Claire Langley

Last month saw a flurry of activity and media focused on climate change, following the release of two major reports on impacts and action by the Intergovernmental Panel on Climate Change (IPCC). Headlines around the world reflected two main messages. First, climate change impacts are happening now on every continent, posing risks that are increasing in severity. And second, in order to stabilize temperatures at 2 degrees Celsius above pre-industrial levels, large-scale changes in the global energy mix are required, changes that must be combined with deep and fast emissions cuts.

Recognizing the Danger

The reports are the second and third installments from the IPCC’s Fifth Assessment Report, a major collaborative effort by over 1,200 international experts and scientists with approval from 194 governments that outlines the latest scientific findings on climate change since the last assessment report in 2007. An earlier installment released in September 2013 on the science of climate change was the first time the IPCC stated unequivocally that climate change is happening and is caused by anthropogenic, or man-made, activities.

According to the IPCC, if the world continues along its current emissions path, temperatures will increase by up to 4.8 C by 2100. To put it another way, the recent United Nations Environment Program (UNEP) emissions gap report states that the world needs to reduce up to 8 to 12 gigatons of carbon dioxide-equivalent from the atmosphere in order to have a good chance of remaining below a 2 degrees Celsius temperature increase above pre-industrial levels—the goal agreed to in the U.N. climate change negotiations. This is approximately equivalent to removing the annual emissions of the United States once and a half over from the atmosphere. And the consequences for the world of failing to do so are grim, with predicted widespread crop failures, water shortages, loss of biodiversity and increased conflict over access to diminishing resources. That action is necessary is not in doubt.

Adding to this, the U.S. government released its third National Climate Assessment today, presenting the latest scientific evidence on climate change impacts in the United States. The report indicates the effects global climate change is already having on the country, highlighting severe weather events and the scale of the economic impact. According to the report, temperatures have already increased 1.3 to 1.9 degrees Fahrenheit since 1895 (most of it since 1970) , and in most areas of the United States temperatures are projected to rise by another 2 to 4 degrees Fahrenheit over the next few decades, or under a high emissions scenario potentially increasing by 5 to 10 degrees Fahrenheit.

US Government Action

Governments are moving to reduce emissions and U.S. action remains key, not only because it is the second largest emitter, but because U.S. leadership is a precondition to ambitious action by large developing countries such as China. In June 2013 the White House released a climate action plan, which contains provisions for both adaptation and mitigation measures at the domestic level. The plan includes over 60 policy proposals designed to support the U.S. international target of reducing greenhouse gas emissions by approximately 17 percent below 2005 levels by 2020.

The White House climate action plan, however, has no ambitions for pricing carbon—the most economically efficient way of getting producers and consumers to take into account the costs for the climate of CO2 emissions. Unfortunately, this reflects political reality in the United States. In 2009, following the election of President Obama, Congress sought to pass a cap and trade bill that would price carbon by capping CO2 emissions. While the House of Representatives passed the bill, the inability of the Senate to act buried the prospect of cap and trade and possibly all efforts to price carbon in the United States, at least in the near term.

The absence of any realistic prospect that Congress will act constructively on climate change anytime soon means that federal government action to reduce U.S. CO2 emissions has had to rely increasingly on executive action. In particular, this means using Environmental Protection Agency (EPA) authority to reduce CO2 emissions from the power sector and tighten fuel efficiency standards for existing cars and trucks—representing 31 percent and 27 percent of U.S. greenhouse gas emissions respectively. These efforts are significant and have the potential to bend the trajectory of U.S. emissions. Indeed, according to some estimates, new EPA regulation of emissions from the power sector will reduce total U.S. greenhouse gas emissions up to 700 million tons of carbon per year in 2020, and new standards to improve the fuel economy of vehicles could reduce annual emissions by a further 50 million tons of carbon in 2035—or a combined 11 percent of current U.S. emissions. However, these EPA regulations are being challenged in the courts and the extent to which they will be successfully implemented and over what time remains unclear. The White House plan also requires federal agencies to consume 20 percent of their electricity from renewable sources by 2020 and to increase their energy efficiency, which are additional to the tighter energy efficiency standards for appliances developed by the Department of Energy.

In parallel to federal action on climate change are a range of state-level responses. The most potentially significant is California’s cap and trade bill which aims to reduce the state’s CO2 emissions to 1990 levels by 2020—representing approximately a 30 percent reduction in the state’s emissions. This is important because California is itself the world’s 8th largest economy and 19th largest emitter and has traditionally been a leader in addressing environmental challenges that have subsequently been adopted federally. Hawaii and Minnesota have also established economy-wide emissions reduction targets, and several U.S. and Canadian states and provinces have banded together to create regional climate cap and trade initiatives including the Regional Greenhouse Gas Initiative and the Western Climate Initiative. In addition, 35 states have renewable energy targets and more than 25 states have energy efficiency targets.

While all this action is encouraging, it remains the case that more is needed to stabilize temperatures at 2 degrees Celsius above preindustrial levels. In this regard, what the United States is prepared to do post-2020 will determine whether this leads the world onto a more sustainable emissions trajectory.  

The findings, interpretations and conclusions posted on Brookings.edu are solely those of the authors and not of The Brookings Institution, its officers, staff, board, funders, or organizations with which they may have a relationship.

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