In a year where deadly hurricanes, floods and heatwaves have dominated global headlines, the United States has just elected Donald Trump, a climate denier.

During the campaign, Trump has called climate change a hoax, a scam, and has promised to roll back environmental protections and withdraw from international climate action.

As a global superpower and the world's second-largest emitter, what the US does will have ripple effects around the world.

But unpicking the climate policies in his own country could prove unpopular and hard to achieve. And the world is in a very different place since his first stint in the White House — the clean energy transition is now a global race for dominance.

Red states back the green boom

On American soil, Trump risks a blowback from his own supporters if he makes good on his promise to end the landmark climate policy passed by the Biden administration two years ago.

"My plan will terminate the Green New Deal, which I call the Green New Scam," Trump said.

Curiously named, the Inflation Reduction Act (IRA) is a sweeping package that unleashed funding and tax credits for climate change investments across America, as Columbia Business School climate economist Gernot Wagner explains.

"The Inflation Reduction Act, in many ways, is the most ambitious climate policy anywhere, period," Mr Wagner said.

A staggering 85 per cent of the investments from the IRA have gone to projects in Republican congressional districts — Trump communities.

The IRA has poured billions of dollars into clean technologies across the country, such as electric vehicles manufacturing, batteries, solar, and household upgrades.

"So for consumers, $US6 billion ($9 billion) or so set aside for heat pumps and upgrading your home electric system and insulating your home and buying your induction stove and all these sorts of things."

But the most significant funds flow to big businesses to drive manufacturing and investment in clean energy technology across America. It has increased overall investment in climate solutions by using tax credits.

"You don't just get a blank check. You actually need to spend at least twice as much money. This full package encapsulates a trillion plus in spending, leveraging over $3 trillion in private investment," Mr Wagner said.

There are two key reasons why red states have benefited so significantly, according to Mr Wagner.

"Renewables take up space … states with lots of land [are] typically Republican, often Republican.

"The second [reason] in many ways is by design, by political design."

This complicates the path for Trump in unwinding it. The IRA has many fans within his own party, politicians who see their home towns and counties benefiting from new manufacturing projects and jobs.

The IRA also offers carrots to fossil fuel companies to implement technologies to curb their emissions, such as carbon capture and storage.

"It means on the one hand, we are paying industry to get cleaner … it also of course means that there are champions for the IRA in fairly unusual places," said Mr Wagner.

Elon Musk is the X factor

One of the people to benefit from the IRA is his key ally, Tesla tycoon Elon Musk.

The IRA offers tax credits for people buying Telsa's electric cars, but more importantly, it has wide-ranging tax credits across the entire battery production chain.

According to one analysis from Johns Hopkins University, the IRA has contributed $US44 billion in manufacturing capacity. More than 90 per cent of that manufacturing investment has gone into the battery supply chain, driving down the overall cost of electric cars.

It found that US-made batteries receive strong support from the IRA, totalling about one-third the cost of a battery.

Mr Musk's overwhelming support during the election campaign may just add another obstacle for Trump in winding back the climate legislation.

Renewable investment the future

The IRA's success underscores how different the world's standing on clean technologies is today compared to Trump's first presidency in 2016.

The world's economies are being reshaped around clean technologies, according to climate scientist Bill Hare.

"We have fundamentally more investment going on now in clean tech than fossil fuels, that's very different than five or six years ago. That's going to be, I think, a big tailwind in keeping action moving forward."

Mr Hare has been a key figure in international climate spaces since 1989 as a climate scientist and IPCC lead author, and now leads the think tank Climate Analytics.

He believes that American businesses will put pressure on the Trump administration to maintain its position in clean technology development.

"American business hates to fall behind on the technology space. If the US goes slow, it's going to be overtaken by China, the EU and others. That'll be something that'll be worrying American capital a lot."

In many ways, the US has already been overtaken by China's astonishing clean technology boom.

Mr Hare points out that the Biden administration has overseen a boom in oil and gas.

China takes the lead in the clean energy transition

Kingsmill Bond from the Rocky Mountain Institute, which analyses clean energy trends, says China is driving the transition to renewables.

"This obviously confuses people because in most areas for the last 30 to 50 years, the United States has led and other countries have followed," Mr Bond said.

"China is clearly leading in almost every aspect of the energy transition and therefore we need to focus more on what happens in China and what happens in in other countries."

This comes after years of government investment in renewable energy technologies to put them ahead of the rest of the world.

"There is this race to the top to lead the energy technologies of the future … you cannot hold back the tide of change," he stated.

Bill Hare says this race has gone global.

"The reason why China has got the jump on critical technologies, electric vehicles, batteries, manufacturing capacity and renewables is because to some extent, policymakers in the US and Europe went to sleep at the wheel. They didn't roll out the kind of incentives needed in the way that China has.

"But I don't think it's a foregone conclusion that China would maintain the lead in these indefinitely. I think the right level of policy action, levers and incentives would enable others to catch up. And not just Europe and the US, but also other centres.

"We're seeing a growth of, for example, electric vehicle manufacturing in India now at scale … the numbers are quite staggering."

Mr Bond says while international climate pacts such as the Paris Agreement have focused on the need to help the global south, the evidence shows these regions are pushing ahead on climate change, regardless of who is in the White House."

And China's boom is making it cheaper for other countries to make the transition.

"We found that, in fact, 20 per cent of the global south has already leapfrogged what's going on in the global north and that 60 per cent of the global south is just rising up like everyone else.

"Because it's not surprising for the folks in Pakistan or Namibia or Bangladesh or Uruguay or Chile or Vietnam, they too want local cheap energy, and they too can buy cheap stuff from China and harness the sun. So why wouldn't they? And that's exactly what they're doing."

And Bill Hare says China is now in a position to start reducing its emissions, which could offset some of the damage of the US falling behind.

"We think in our own calculations that China has peaked its emissions already, and [they will] begin to start going down. If they double down on that, then the damage from the US being out of the game for four or five years will not be catastrophic."

Vacancy for climate leadership

In his first presidency, Trump unpicked over 100 pieces of environmental policy across the US, including regulations on fuel efficiency standards aimed at reducing transport emissions, and became the first and only country to withdraw from the international climate pact, the Paris Agreement.

He again derided the Paris Agreement during this year's campaign, leading many experts to believe he will again withdraw from it and possibly the UN treaty on climate change, the UNFCCC.

But Mr Hare says the fears of Trump's first withdrawal were overstated.

"When that happened, many pundits predicted that the Paris Agreement would collapse and stop, but it actually didn't. Whilst a shock at the time, in retrospect, the Trump withdrawal of the United States did not really significantly affect momentum."

Climate experts watching to see if China will step into an international leadership role will get an indication at COP29, the world's annual climate conference, next week.

A key goal for this year's COP is climate finance: getting wealthy countries like the US and Australia to commit more funding to help developing countries address the threats of climate change and transition their economies.

"There's no doubt that the Trump election will cast a shadow over the COP. It is going to make the task of agreeing on a new finance goal much more difficult," says Mr Hare from Azerbaijan, where it is being held.

The biggest concern is Trump's climate handbrake extending beyond the US.

Christian Downie is an associate professor in the School of Regulation and Global Governance at the ANU who focuses on climate politics and diplomacy. He's watching to see which countries step into the climate leadership space.

"I think Europe will be considering the role it can play. But I think what's going to be more important is countries in Asia," he said.

"Will countries like China work more closely with the European counterparts to take a leadership role? Will Brazil, who's going to be hosting the UN negotiations the following year, take on more of a leadership role?"

In a warming world, any delay has consequences

This doesn't mean that there will be no impact on the climate from a Trump presidency. In fact, a Carbon Brief analysis predicted that emissions would rise under Trump by a staggering 4 billion tonnes by 2030 if the IRA was wound back.

The world is halfway through the "critical decade" for climate action, and Trump will be president until 2029. His actions will, at the very least, impact his country's ability to meet its 2030 targets.

This all matters, as rising global temperatures are tied directly to how much carbon pollution is emitted. More emissions, more warming.

More emissions also means more climate disasters, like the hurricanes that hit during the presidential election campaign, and the recent devastating Spanish floods.

"These things are going to get worse and worse. And no amount of bluster from climate deniers is going to change that. There's going to be increasing political pressure on politicians everywhere to act. So I think there's going to be more of a reckoning to come," Mr Hare warns.

For Mr Wagner, the clean technology momentum cannot be stopped, but it can be slowed in the US.

"The raw economics, the plant-level economics, the bottom-up business case for renewables is there. There's nothing that will stop that. What Trump can do is delay, obfuscate, attempt to withdraw the IRA.

"I think the biggest problem with a Trump presidency is the uncertainty."