As scientists who have dedicated ourselves to research on a wide range of issues related to energy and climate, we write to express our grave concern about the U.S. withdrawal from the Paris Agreement. U.S. withdrawal would pose a serious risk to a hard-won effort to have the world's nations reach a voluntary agreement to begin to cut their emissions to a level that would hold global warming below 2 ºC, about a third of the temperature difference between now and the last ice age.
The Paris Agreement was established under an understanding of equity and the principle of common but differentiated responsibilities and respective nations' capabilities, a long-standing approach to international climate mitigation efforts. The Agreement is voluntary, and the contributions of emissions reductions were proposed by each respective nation. They were not forced upon nations.
The simple facts are: 1) burning coal, oil and natural gas puts carbon dioxide into the atmosphere; 2) once carbon dioxide enters the atmosphere, a large part of it remains there for centuries; 3) carbon dioxide in the atmosphere traps heat, warms the planet, changes the climate, and will have consequences for people and for ecosystems. The increased concentration of CO2 also acidifies the oceans, with dramatic consequences for marine ecosystems that are already occurring.
In addition to the climate change-related effects, reliance on fossil fuels has another very tangible cost: using coal for electricity and industrial processes, or gasoline and diesel for transportation leads to the emissions of air pollutants that increase deaths and serious illnesses from breathing polluted air. Worldwide four million people die every year from this pollution, and tens of thousands die of it in the USA every year. In addition to the death toll, the loss of productivity and the health care costs associated with pollution-related illness pose a serious harm to our economic vitality.
The White House cited the economic needs of the people of Pittsburgh - home to Carnegie Mellon, where the rigorous study of energy and climate are a top institutional priority - as one motivation to withdraw from the Agreement. We have a vibrant and growing city; birthplace of a global robotics movement, home to high-tech start-ups, test beds for autonomous mobility and smart lighting systems, and a model for next general urban development. We also have cutting edge energy research and development efforts that have generated greenhouse gas emissions inventories for the city, as well as climate impact and action plans. For these reasons, we are confident in saying that in the short run Pittsburgh does not stand to benefit substantially from the U.S. withdrawal from the Paris Agreement and in the long run Pittsburgh would lose. We enthusiastically support our Mayor in his commitment to honoring the terms of the Paris Agreement.
The window for serious global climate change mitigation efforts that could allow the world to avoid large negative effects is rapidly closing. The Paris Agreement provided an initial step in the direction of global climate action, but much more is needed. Leaders need to step up to the challenge by forging binding international agreements and domestic policies.
As the federal government begins the process of considering which conditions it would be willing to renegotiate, we call for a clear energy and climate policy from the administration that will lead to meaningful greenhouse emissions reductions. Failing to do so leads the country and the world into a place of increased uncertainty and danger. America led the world in starting to clean up air and water, and we profited by selling pollution reduction equipment to the world. This is not the time to cede America's leadership to others.
See the article on the Carnegie Mellon University News page here.