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Yesterday US president Donald Trump declared “we’re getting out” of the Paris climate agreement, swiftly followed by a pledge to begin negotiations to re-enter it on “better” terms.

The decision will unavoidably damage businesses and research in the US, as well as the health of its population and its international reputation. But how much damage will it inflict on global efforts to keep warming below 2°C? In short, has Trump doomed us all?

Current political pledges, including US targets set by the last president, Barack Obama, add up to a global temperature rise of 3.6°C. To bring that down to 2°C, global emissions must peak as soon as possible, ideally within the next three years, and cease entirely by 2070. That’s a tall order, but the energy sector and industry more generally have undergone a remarkable transformation in recent years. Best of all, much of it is happening on the international stage, independent of US federal decisions.

First, the dirtiest of fossil fuels – coal – is in decline, most notably in the US and China. As Trump is at pains to point out, the US coal industry is dying; most agree his best efforts are unlikely to reverse that. Coal-fired power stations around the world are being retired at unprecedented rates and in the last few years, the amount of coal mined globally has fallen.

At the same time, the cost of renewable energy has been slashed, largely thanks to Chinese investment and development. As a result, emissions from industry and energy have held steady for three years in a row even as the global economy has continued to grow. To many, this signals the early stages of the long-awaited transfer to a low-carbon economy. Suddenly, a global peaking of emissions by 2020 looks possible.

Green economy

There is already movement towards a green economy in the US, despite Trump’s announcement. In the last few weeks, major businesses, including General Electric and Exxon Mobil, have called on Trump to remain in the Paris Agreement. Google, Apple and Facebook have committed themselves to using . None of these elements are dependent on federal participation in the Paris Agreement.

US states and cities can also act without federal leadership. On Thursday, a clearly peeved governor of California, Jerry Brown, said: “Trump has absolutely made the wrong choice.” Brown left no doubt that California – the second largest emitter of greenhouse gases in the US and the world’s sixth largest economy – would pursue its aggressive policies to cut emissions, including a cap and trade programme, energy efficiency targets and a goal to get 50 per cent of its energy from renewable sources by 2030.

“We’re all in,” said Brown, who alongside the governors of Washington and New York announced the formation of the , committing their states to upholding the Paris Agreement. Mayors of big cities across the US like Los Angeles and New York City rushed to make .

So despite a shift in federal policy, action on the ground is likely to continue. “States and corporations have a lot of power – on the same order of magnitude as Trump I’d say,” says of the New Climate Institute in Cologne, Germany. Judging from the sheer anger that was being expressed on Thursday, it is possible Trump’s decision will backfire and end up galvanising more climate action.

Trump’s past statements have already spurred China into action. Once a reluctant actor on the environmental stage, China has been far more forthcoming about its intentions to cut emissions since the US election in November. On Wednesday it made noises about and is to boost energy efficiency and renewables later today.

Trump effect

That’s not to say Trump’s decision will have no effect. Remember that global emissions need to hit zero by 2070. The world is still emitting 40 gigatonnes of carbon dioxide each year and the US is the second largest emitter. Each year, it emits 1.5 gigatonnes of CO₂ that will stay in the atmosphere for hundreds to thousands of years. Zero global emissions isn’t possible without it on board.

More renewables and less coal is great, but it’s not enough. Coal is still responsible for around 40 per cent of the global energy mix. We also need to eliminate gas and oil, find a way to fly and ship goods without burning any fossil fuels, and feed 9 billion people without emitting vast quantities of CO₂ and methane.

In practical terms, that means a massive acceleration of the move towards renewables. We need to rebuild electricity grids to accommodate them; re-think how we price them so they can outcompete fossil fuels; and come up with cheap solutions to store vast quantities of electricity. We also need to find new fuels for aviation and shipping, and in all likelihood rethink the West’s meat-heavy diets. There’s no denying that all this is helped by strong political incentives, but the global reaction to Trump’s decision shows the will is still there.

The timing of the US pull out is particularly bad. According to of the World Resources Institute, there’s enough momentum in the US system to keep the low-carbon ball rolling until about 2025, by which time the US will have a new president. But as global emissions need to be in a downward spiral by 2025 the next few years are going to be critical for accelerating action after 2020 – something Trump is unlikely to prioritise. The terms of the Paris Agreement mean the earliest any nation can formally leave is 5 November 2020, four years after it came into force. This just happens to be two days after the next US presidential election, meaning this will remain a hot political issue.

Climate fund

And then there’s money. Under the Paris Agreement’s Green Climate Fund, wealthy developed nations have promised billions in finance for developing nations that will experience the worst impacts of climate change. The US promised $3 billion. On Thursday, Trump was adamant that this was a bad deal for the US. Last year, the country paid $1 billion into the fund. The remaining $2 billion is unlikely to materialise.

China seems likely to stay the course but changes to the Green Climate Fund could rub smaller developing nations the wrong way. “Unfortunately I think negotiations will be injected with a dose of acrimony,” said Christina Figueres, head of UN climate talks, on Thursday. But there is no chance of Trump getting a better deal, despite his wishes. “This is a multilateral agreement. That’s why it took six years. No one country can unilaterally renegotiate,” she said.

Just how much hotter the world will get as a result of the US pull out is difficult to predict but pessimists will point out that even a fraction of a degree could matter if it pushes us past irreversible tipping points. To avert that, we are now probably a little more likely to reach for geoengineering, large-scale interventions in the world’s climate systems.

With Trump in the White House, there’s really only one option on the table: to work around him. If anything, this week has shown how anger and dismay will shift political alliances to do just that.