In June, 2017, I attended The future of the Paris Agreement and global climate change cooperation without U.S. leadership at the Brookings Institution. The event focused  on what is next for the Paris Climate Accord following Donald Trump’s announcement that the US will leave the agreement. There were many good insights, but what struck me most was the enormity of Trump’s actions.

At the event, there were many people deeply connected to the international climate policy community. There were people who attended COP 21, (the Paris Climate conference). There were people there who were involved with the crafting of the Kyoto protocol. Listening to them was eye opening. When you understand the history that brought us to Paris, Trump’s action is breathtaking.

The Paris Accord represents 20 years of work toward finding a mechanism that the world could agree on. The Paris agreement was the first time nations of all ilk agreed to work together to cut emissions. It overcame developing countries’ objections that climate change action was about oppressing them. It overcame developed countries’ objections that they could not do it alone and had to have developing countries on board. It was precipitated by the two biggest emitters, the US and China, laying on the table bold commitments to cut emissions before the Paris conference began.

It took years of skilled negotiation to get the agreement done. The Paris Agreement moved us past arguing about past emissions and how much more of the burden the west should bear because we have emitted so much. The Paris Agreement moved us to a focus on action. A focus that gives us hope that we can ease or stop the suffering that a warming planet is sure to cause.

With one thoughtless action and carelessly crafted speech, Trump undid years of work and moved us back into the Us Versus Them argument. The argument that had stifled progress on climate change for years. Through Trump, we have thumbed our noses at the rest of the world. To think this will not have repercussions beyond climate policy is truly naive.

The glaring reality is that the president and his advisors lack the experience or understanding to deal with these issues. Being a part of the Paris Agreement was not some political chip for Trump to cash in. It is a milestone in the history of humanity that showed what American exceptionalism is truly about. Without our leadership, it could not have happened. Without our active participation, it might not succeed. We will not be exempt from the consequences of that failure, should it happen.