(NOAA/NASA)

The author, Benjamin Sanderson, is a climate scientist at the National Center for Atmospheric Research in Boulder, Colo. He works on future climate projections and scenario development.


President Trump may soon announce that the United States is withdrawing from the Paris Agreement, putting the nation at odds with the almost every other country on the planet except two: Syria and Nicaragua. What happens in the aftermath of this decision could have vast implications for the world our descendants inherit.

If the U.S. decision causes the Paris Agreement to fail, any chance of keeping global temperatures below 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial temperature will effectively be nullified.

This is a good time to remember that even two degrees of change will have significant global ramifications. Temperature records of the past will be yearly events, most years will likely have an ice-free Arctic, and extreme precipitation events are projected to markedly increase.

After 200 to 300 years, two degrees of warming would eventually lead to sea levels rising by up to four meters (13 feet), which would partially flood present-day London and New York, and completely submerge the New Orleans metropolitan area.

In short, it is well-established that the world our descendants inherit will already present them with significant challenges, and the consequences of even a short delay in the next decade could make it worse.

But this is no time for fatalism. The withdrawal of the United States from the Paris Agreement places the world in a highly uncertain geopolitical situation, which could play out in a number of ways. The rest of the world has already expressed solidarity in the face of a U.S. withdrawal — notably China and the European Union have made statements that they will continue in their respective mitigation efforts and adopt leadership roles.

President Trump has decided to pull the U.S. out of the Paris Agreement. Here's what you need to know. (Daron Taylor/The Washington Post)

And this should be heartening because the remaining signatories to the Paris Agreement represent an unprecedented negotiating bloc comprising the majority of the world’s economies, which can now potentially adopt a stronger stance in the absence of a United States keen to dilute its commitments. Moreover, this bloc would be well-positioned to collectively impose penalties on noncompliant states.

Meanwhile, in the United States, many states and leading companies are already committed to mitigation, and economic forces are undermining some of the greatest sources of emissions, such as coal-fired power plants.

In addition, the majority of the U.S. population thinks that climate change is a problem and that emissions should be reduced.

Given the Trump administration’s existing efforts to nullify the Clean Power Plan, which was the primary federal mechanism for reducing greenhouse gas emissions, the practical burden of mitigation action was already placed on cities, companies, states and even individuals — who all have economic and moral motivations to reduce emissions. As such, net U.S. emissions might only be weakly dependent on Washington’s participation in the Paris Agreement over the next few years.

We are in an awkward phase of global climate change where the science is well-established, and we can be confident that significant warming will happen within the next 20 to 30 years. Although there are plenty of detectable warning signs, impacts are only just beginning to be felt by communities. In any case, we can be fairly sure that over the coming years, the daily effects of climate change will be self-evident, and taking a denialist position will become increasingly difficult. When this happens, and the population is directly impacted, it would seem increasingly likely that mitigation action would be demanded by the majority.

Businesses (oil companies included) are well aware that a carbon-restricted economy is coming and their shareholders are increasingly demanding long-term investment strategies that allow those companies to profit in a low-carbon future. One can make the argument that the greatest casualty from U.S. withdrawal from the Paris accord will be the United States itself. By sidelining mitigation investment, and leaving companies to act alone, U.S. companies are placed at a disadvantage while China races to establish itself as the world leader in clean technology.

The world absolutely cannot afford a delay in mitigation, but there is sufficient global movement that the majority of countries, companies and people are committed to reduce emissions. Although the United States is now taking a back seat in this effort, it cannot stop global mitigation efforts from occurring.

Climate change is a great equalizer — irrespective of which groups make efforts to reduce it, the effects will be shared equally by the global population. But equally, climate change and the need for decarbonization will change the face of the global economy in the coming decades. This will create winners and losers, and those who adapt fastest will be the superpowers of the coming century. By withdrawing from Paris, the United States would be betting on a future in which climate change is going to go away, and that is one thing we are sure is not going to happen.