It’s official: After months and months of waiting, of lunging back and forth from pro- to anti-, President Trump will take America out of the Paris agreement.

Walking out into the Rose Garden of the White House, the President told the world that “in order to fulfil my solemn duty to protect America and its citizens, the US will withdraw from the Paris climate accord.”

He claimed that the accord is a “bad deal,” one that is costing American jobs and will ultimately cripple the US economy – something that is demonstrably untrue.

Trump said that he will look for a “better deal.”

“We will begin negotiations to re-enter the Paris accord or an entirely new transaction, on terms fair to the US – it’s businesses, workers, taxpayers,” he added. “So we’re getting out, but we’ll start to negotiate, to see if we can make a deal that’s fair. If we can that’s great, if we can’t that’s fine.”

The US will now join Syria and Nicaragua in a rather ignominious and exclusive club as the only nations that are not part of the global effort to curb greenhouse gas (GHG) emissions.

This decision goes against the will of the American people, 71 percent of which support the Paris agreement. It goes against the will of more than 800 colleges and universities, 1,000 American companies, and even traditionally fossil fuel-oriented giants, including ExxonMobil, Shell, and BP; it also goes against the will of 400 major American cities and 37 states.

Watching from the front row of the gathered crowd with a smile, the Environmental Protection Agency (EPA) chief Scott Pruitt, the strongest anti-Paris voice in the administration, repeatedly applauded and patted the back of Reince Priebus, the White House Chief-of-Staff.

“The bottom line is that the Paris accord is very unfair to the United States. It is transferring coal jobs to foreign countries,” Trump added, reading from a script.

The President also claimed, without citing his source, that “even if the Paris agreement was implemented in full, it is estimated that it would implement two-tenths of a degree of temperature reduction by 2100.”

“This agreement is less about the climate and more countries gaining a financial advantage to the United States.”

His most breathtaking statement came just a few minutes into his speech. Shaking his head, he claimed that the rest of the world went wild when the Paris agreement was signed “because it placed America at a serious economic disadvantage,” a rather extraordinary claim by any measure.

Trump also claimed that the Green Energy fund – one designed to help developing nations make the transition to clean energy grids – was a fraudulent fund and one that America will no longer pay into.

The process of retraction is not immediate. Formal notice of withdrawal cannot be filed until November 2019, after which it will take a year longer before the US is officially removed from the Agreement – so it’s not clear at this point if all the legal strings will be untied in time for the next presidential election in 2020.

Either way, unless something major changes at the top tier of US politics, it’s almost certain that the Paris agreement will lose the participation of the world’s second-most prolific GHG emitter.

In the meantime, it’s likely that the US will continue to inform the UN how its GHG emissions are trending, as it is legally mandated to do so. It will not, however, directly attempt to cut its carbon footprint, nor will it keep up the donations to the UN designed to help poorer nations make the transition to a low-carbon energy infrastructure.

There will be no punitive measures or sanctions directed at the US for taking this path, but it’s likely that this will only exacerbate the recent bout of American isolationism that the Trump administration has single-handedly brought about. In particular, the European Union – collectively the third-most prolific GHG emitter – is likely to turn its back on the US even more so than it already has.

“This is one of the worst decisions that the President has made to date,” Dr Andrew Light, a Distinguished Senior Fellow in the Global Climate Program at the World Resources Institute (WRI), told IFLScience.

“He’s doing nothing more than alienating himself from the rest of the world, undermining US security, and undermining American competitiveness abroad. America will become an international pariah.”

The immediate impact, apart from global shock, won’t be environmental. If anything, it will be a boost to climate change deniers.

By withdrawing from Paris, it sends a clear signal out to the world that it’s fine to ignore more than 97 percent of the world’s scientists – and when the most powerful nation on Earth rejects the basic premise of scientific consensus, then you’d better believe that this will encourage the American people to do so too. This is the most severe symptom yet of the anti-intellectual pandemic that's spreading across the country.

Symbolically, this is a blow to international cooperation on a subject very few people, and very few governments, disagree with. In terms of the damage it will do to the world, however, this is where we can be less certain.

We’ve already outlined the consequences for the US pulling out of the Paris agreement. From increasingly powerful natural disasters to economic crashes, there’s a distinct possibility that America will be a hugely damaged nation by the turn of the next century.

As we also pointed out, however, there is hope. The rest of the world is moving on with their GHG cuts, and sizable US states are continuing to invest in clean energy. The federal government may not be participating in the agreement, but almost the entire world is, and at least a third of the US is too in some way.

Consequently, although it’ll be harder for the ambitious targets of the Paris agreement to be met, it’s still possible that they will be. Additionally, if Trump is thrown out of office in 2020, there’s a chance that his successor may choose to stop the withdrawal process or rejoin the accord.

Unfortunately, this colossal disappointment now means that we’re still facing the prospect of a weakened Paris agreement. The world will now look to the EU and China to lead the pack when it comes to saving the planet from a nightmarish, climate change-ravaged future.

“The rest of the world will look at America in bafflement, but they will move forward,” Light added. “I think that the Paris agreement will be fine – the most damage will actually be done to the United States. That is the very clear truth about this decision.”

This is nothing less than a titanic triumph of ego over reason. It’s an act of considerable self-harm, and one that will be seen as a key moment in history: the point where the US, the global leader, became a shameful shadow of its former self.