“We’re all now part of this drama, will they withdraw or not, but they have already said they won’t do anything substantial on climate policy, and that’s what matters,” said Oliver Geden, a climate-policy analyst who is a fellow at the Institute for Science, Innovation and Society at the University of Oxford.

AD

Calculations by scientists and climate-policy experts point to several key facts underlying this discussion. First, the U.S. emissions cuts were set to make up a major part — more than a fifth between now and 2030 — of the reductions achieved by the Paris climate agreement.

AD

Second, even with the United States and all other countries doing their best to meet their commitments, that agreement still was not strong enough, at least not in its first round of country-level pledges, to keep the world from warming above the threshold of 2 degrees Celsius (3.6 degrees Fahrenheit) that scientists have identified as a marker beyond which we’ll see truly “dangerous” change. (We’re already a bit over 1 degrees Celsius now above preindustrial temperatures.)

This means that in 2017, to tackle climate change, the world needs a more ambitious United States — not a country that will abandon Paris entirely, or at minimum, scale back its commitments to that agreement.

AD

Let’s take this in pieces:

1. The United States, measured by emissions cuts out to 2030, makes up 21 percent of the Paris climate agreement. According to an analysis from the think tank Climate Interactive, the U.S. pledges would account for 21 percent of the total expected emissions cuts out to the year 2030 under the Paris agreement.

Under the Obama administration, the United States promised to slash emissions by 26-to-28 percent below 2005 levels by 2025. This made the United States a major contributor to the deal during its early implementation over the critical next 10 to 15 years, a time period that will heavily determine what kind of a planet we end up with.

“Trump has already damaged U.S. prospects for meeting its Paris Agreement goal by undermining federal regulations and casting a dark shadow of uncertainty across the energy sector,” said Ellie Johnston, the climate and energy lead for Climate Interactive. “Fortunately, many U.S. states, cities, and businesses are not letting this opportunity slip away and are still taking action, but it is too early to tell how much they can close the gap created by the Trump Administration.”

AD

AD

Indeed, just because Trump is president, that doesn’t mean that the entire 21 percent contribution of the United States will be lost. The country has already lowered its emissions 12 percent below their 2005 levels as of 2015, according to the Energy Information Administration. That’s largely due to factors like the switching from burning coal to burning natural gas brought on by fracking.

But with President Trump’s moves to roll back Obama-era regulations that were designed to achieve the U.S. pledge, it’s unlikely the country will achieve the remaining reductions. As a new analysis by Climate Action Tracker points out, Trump policies “are projected to flatten U.S. emissions instead of them continuing on a downward trend.”

2. Paris was never enough to hold the planet’s warming “well below” 2 degrees Celsius anyway. It has been clear from the start that these pledges were not enough and that more will have to be done to get warming under control.

AD

AD

A 2016 study in Nature, for instance, found that the current commitments under Paris “still imply a median warming of 2.6—3.1 degrees Celsius by 2100.”

“The arm of the laws of physics is not so easily twisted,” said Joeri Rogelj, a researcher at the Institute for Applied Systems Analysis in Laxenburg, Austria, and a lead author on the study. “Whatever you delay now, you will have to make up later, and it’s obvious that limiting warming to 2 degrees or 1.5 as was mentioned in the Paris agreement is an incredible challenge which will require lots of innovation, new technologies, new ways of thinking, entrepreneurship.”

Some scientists are already suggesting that the 2-degree goal may be lost to us. “There’s so many things that need to go right for 2 degrees. Essentially we’ve emitted too much, which makes the 2-degree challenge hard,” said Glen Peters, a senior researcher at the Center for International Climate Research in Oslo.

AD

AD

If there’s any chance left, it’s clear that nations need to ramp up their ambitions to keep warming below 2 degrees Celsius — something that Paris is designed to do, through regular meetings aimed at determining what adjustments need to be made to meet that goal.

It may well be that the world will need to pioneer geoengineering policies to control temperature, or “negative emissions” technologies to extract carbon from the air to buy some time.

3. Trump, in the Paris agreement or out of the Paris agreement, is dulling the U.S. contribution to fighting global climate change and punting the problem to the rest of the world.

Whether the United States stays in or out of the Paris agreement, the upshot is the Trump administration is delaying action on climate change, and is defining U.S. ambition downward rather than upward. Since climate change is a collective problem, that means that the slack must be made up some other way.

AD

AD

“It is a global problem and it’s a cumulative problem,” Rogelj said. “Everything we are not doing today somewhere on the globe will have to be compensated somewhere else, or later.”

Other countries may be able to make up the slack for the United States. The Climate Action Tracker analysis suggests, for instance, that progress in India and China could be enough to offset any U.S. backsliding. “If something happens in a positive direction in the rest of the world, that can completely offset what’s going on in the U.S.,” Peters said.

But filling the U.S. role in the Paris agreement is only part of the problem — since that agreement itself doesn’t go far enough, other countries would also have to ratchet up their ambitions further if the United States falls behind.

AD

“Somebody would have to cover that part [for the United States], and then there’s still the gap for the whole world,” Geden said.

AD

The conclusion is pretty clear. Trump may stay in the Paris agreement and define the U.S. contribution down, or he may leave the agreement entirely. The latter would be far more controversial.

But either way what it all means is that the United States is ceding a leadership role in an increasingly important global arena.