US President Donald Trump has withdrawn the United States from the 2015 Paris climate change agreement, the landmark United Nations treaty that many of us worked so hard to achieve. Trump is making a mistake that will have grave repercussions for his country as well as the rest of the world.

Trump claims that he will try to renegotiate the deal reached in Paris, or craft a new one. But leaders from around the world have already hailed the agreement as a breakthrough in the fight against climate change, a victory for international cooperation, and a boon to the global economy.

Among the many challenges we face today, climate change is unique in its global scale. It affects every element of life on this planet - from ecosystems and food production to cities and industrial supply chains. Viewing climate change as strictly an "environmental" problem misses the point entirely.

We might charitably assume that Trump simply does not understand the implications of his decision. And yet, regardless of what he thinks, we know that he is surrounded by advisers who know very well what is at stake.

On the campaign trail, Trump promised to create jobs and protect US workers from the ravages of the world. But his decision undermines every one of those goals, and it goes against the wishes of a vast majority of Americans, including many of his own supporters. By turning his back on the Paris agreement, he is increasing the US' exposure to the devastating effects of climate change - many of which they are already experiencing. Moreover, he is undercutting jobs in the thriving renewable-energy and electric-vehicle sectors, which are increasingly employing the very workers he purports to represent.

When I was a member of the French government participating in a global tour to build consensus for climate action - an effort that culminated in the Paris agreement - I experienced firsthand what US leadership can achieve. It is tragic to watch that force for good be subverted by denial and myopia.

By burying their heads in the sand, Trump and his advisers must be hoping that reality will simply go away. They have somehow concluded that the US will be spared from the droughts already destroying farms in California's Central Valley, the rising sea levels already flooding coastal cities, the storms and wildfires routinely ravaging vast swathes of the US countryside, and the water- and food-supply disruptions that threaten us all.

Other parties to the Paris agreement have responded to Trump's decision with strength, thus proving the resilience of the agreement itself.

The world's response will be clear at the G20 Summit in Germany in July. Already, the European Union, China, India, Canada, and Pacific Rim and South American countries have recommitted to the goals of the Paris agreement.

Trump's decision is completely at odds with the current global atmosphere of cooperation. The world's major economies are reaching new agreements every day to collaborate on research and development, infrastructure investment and industrial strategy. They are working together to achieve a low-carbon economy, and to make 2020 the year that global greenhouse gas emissions will have peaked.

EU leaders are already meeting with their Indian and Chinese counterparts to find areas where they can cooperate on developing clean energy and green infrastructure. Massive investments will be made in these areas, and the European Central Bank, the Asian Infrastructure Investment Bank, and many other institutions are devising mechanisms to finance them.

Even the most optimistic among us did not predict that the old fossil-fuel paradigm would change so quickly. But Europe is phasing out coal-fueled energy production. And India, China, and the Republic of Korea are rapidly shifting their investments away from coal, and toward renewable-energy sources.

Worldwide, the competition is about "who can go green the fastest."

It is a shame that Trump has decided to shirk the US' global responsibility and turn his back on these developments. His decision is a blow to so many people - including a great many Americans - who have worked hard to be a successful part of the new economy.

Still, Trump cannot take all of the US with him. State- and city-level climate action is sweeping across the US, increasing in scale and ambition. Trump's historic mistake represents an obstacle to that collective action; but it can hardly stop it. Just as Chinese companies are now training US coal workers to build wind farms, the rest of the world will continue to work together, and build the markets and workforce of the future.

The author, former French ambassador to the UN Framework Convention on Climate Change, is CEO of the European Climate Foundation, and a professor at Sciences-Po, Paris.

Project Syndicate