John D. Sutter is a columnist for CNN who focuses on climate change and social justice. Follow him on Snapchat , Twitter and Facebook or subscribe to his email newsletter.

(CNN) If the United States bails on the Paris Agreement on climate change, as CNN is reporting , the results could be catastrophic both for this country and the planet.

It would be a middle finger to the future.

The worst part: There is absolutely no reason for it. Aside, perhaps, from bravado and arrogance.

In walking away from the Paris Agreement, President Donald Trump would be turning his back on the entire world and on the consensus of climate science. Every nation except Syria, Nicaragua and now, potentially, the United States, is part of the accord, which calls for an end to the fossil fuel era -- and limiting global warming to at most 2 degrees Celsius above pre-industrial levels . (Nearly 200 countries or parties have adopted the agreement and 147, including the United States, at least for now, have ratified or approved it , indicating a stronger level of commitment, according to the UN Framework Convention on Climate Change).

I'm sure that target -- considered the "north star" of climate policy -- sounds ridiculously abstract and wonky. But the 2 degrees goal is incredibly consequential. The fate of the planet -- and the mess we shove on future generations -- hangs in the balance.

Inaction on climate change will have disastrous consequences

Consider for a moment what is at stake with climate change: rising seas, flooded coastal cities, mass extinction, searing drought, human displacement, migration crises, deadlier heatwaves, crop failures, stronger storms.

This isn't some meaningless list plucked from an Al Gore PowerPoint. Our fingerprints are on many of these disasters now . As humans burn fossil fuels, chop down rainforests and pursue inefficient and polluting agricultural practices, we are causing heat-trapping gases like carbon dioxide to build up in the atmosphere. That acts like a blanket, gradually warming Earth.

Already, we've warmed the atmosphere about 1 degree Celsius in the fossil-fuel era.

The science on this is solid. US officials saying otherwise is negligent.

"It says to me and my community that they don't care what they do with the environment," Esau Sinnok, a college student from Shishmaref, Alaska, a community that voted in 2016 to relocate because of climate change, told me on Wednesday. "They don't care. They don't believe in climate change."

I've talked with biologists who say we are on the verge of Earth's sixth mass extinction event , with climate change being a major driver. Without massive changes, three-quarters of all known species could disappear in a couple centuries.

This stuff is just absolutely beyond nasty. It's abhorrent. And it's unthinkable to me that we could know these stories and still choose to do nothing. Because we know this: The more pollution we create, the greater the risks. Smoking is an analogy many climate scientists use often, and for good reason. Can you keep smoking cigarettes for four more years and avoid dying from lung cancer. Maybe? But...

The rest of the world should move ahead without the United States

There's a terrifying math to climate change: We can only create so much pollution before we ensure the Earth will cross that dangerous 2-degree threshold, with consequences that are both immoral -- we can stop this if we want to -- and expensive.

agreement that includes the world's second biggest polluter. Greenhouse gases spread across the atmosphere. They don't adhere to national borders. So the process of fixing climate change, too, must be an international effort. Even with the full participation of the US, the Paris Agreement wasn't nearly enough -- on its own -- to avoid the very worst of global warming. Trump's withdrawal from the agreement would only up the odds of catastrophe -- and would do so considerably. The exit would deliver a considerable blow to what needs to be a globalagreement that includes the world's second biggest polluter. Greenhouse gases spread across the atmosphere. They don't adhere to national borders. So the process of fixing climate change, too, must be an international effort. Some will argue that the Paris Agreement will survive without Trump and without the US . I certainly hope that is true. A recent report from Climate Action Tracker , a research group, finds China and India -- the other two of the top three global climate offenders -- are doing so much better than expected at cutting their emissions that the agreement can survive and meet its goals without US participation, at least temporarily.

The risk remains, however, that the Paris Agreement falls apart without the United States.

A China-US partnership on climate action is the main reason the world agreed to this accord.

Without the US as its partner, China -- with India and the EU -- could emerge as the global leader on climate. The agreement could succeed in spite of the United States. Or it could be weakened to the point of irrelevance.

Then, our best hopes for a livable, safe and clean future would start to fall apart, too.

Doing something about climate change is an 'America first' strategy

Again, the worst part of this: The US withdrawal is completely nonsensical.

Nearly seven in 10 American voters support the Paris Agreement , according to a November 2016 survey from the Yale Program on Climate Change Communication. So, there's little need for political cover.

And legal experts have said the Trump administration could remain part of the agreement without being held to the promises the Obama administration made to cut emissions and slow global warming. No, that's not ideal. But it's far and away preferable to a complete exit. Think of the Paris Agreement like a global party, former Obama climate negotiator Todd Stern told me recently. It's a party that gets way less interesting if one of the coolest and most important people just up and leaves -- with fanfare.

"All of a sudden it feels like, well, this isn't a very interesting party," Stern said in early May.

Plus, it's in America's interest to pursue a clean energy economy. There are more jobs in the United States right now in the solar industry than in coal mining. Yes, California and other states (Iowa got more than 35% of its electricity from wind power last year, amazingly) are moving ahead with or without Trump. But the federal policies -- both the signal they send and the emissions they control -- matter. They could point the United States toward a cleaner future or, as now seems apparent, back into the dirty fossil fuel era, with all the associated dangers.

The other gamble: The US risks getting left behind by China in the clean energy economy.

The best those of us who care about the Earth and its future can hope for is that Trump would change his mind. Officials have told reporters Trump will withdraw. But Trump is known for changing his mind at a moment's notice. On Wednesday, the President tweeted that he "will be announcing my decision on the Paris Accord over the next few days ."

Other than that, the best case scenario is for China and the EU to take the lead on climate. For the US to be left behind. And for the rest of the world to spite Trump and the United States by picking up the slack for American pollution.

The worst case scenario? I almost don't want to go there.