The US will be absent from key UN climate talks that start on Monday, a further sign of Donald Trump’s scornful dismissal of the climate crisis. But Democrats’ crushing win in the US midterm elections has delivered a timely shot of optimism to countries now looking beyond the Trump era of climate obstruction.

For the second year in a row, there will be no official US government presence at the annual climate summit, this year known as Cop31 and held in Antalya, Turkey. While almost every other country in the world sends delegations to the talks, Trump has derided the climate crisis as a “hoax” and “bullshit” and triggered the withdrawal of the US from the entire international climate framework.

“This summit rejects reality by failing to acknowledge that extremist climate policies are destroying countries around the world,” a White House official said, confirming that the administration would not send anyone to Cop31.

The snub is so severe that about 20 members of the US Congress heading to the summit have been denied usual state department assistance, requiring them to turn to philanthropic funding for the trip. “I’m glad we found a way to get there, but it is insane,” said Sean Casten, a Democratic congressman who is attending Cop31. “We have a lot of rebuilding to do. It hinges on Congress to maintain diplomatic continuities at Cop and minimize the damage until adults are back in the White House.”

Trump’s active support of fossil fuels, evisceration of pollution limits and throttling of clean energy projects has caused the US to become an outlier among wealthy countries, a recent UN report found. While all the other 20 major economies reduced or slowed their carbon pollution last year, the US was a “major exception” by emitting an extra 133m tons of planet-heating gases from the burning of coal, oil and gas, the report states.

Despite the world rapidly surging past “safe” temperature thresholds because of such pollution, and escalating heatwaves, floods, droughts and other calamities, Trump has remained defiant. “If you don’t get away from this green scam, your country is going to fail,” the US president told other world leaders at the UN last year, adding that the climate crisis was “the greatest con job ever perpetrated on the world”.

But the Democrats’ stunning success in the midterms last week, wresting control from Trump’s Republicans in both the House of Representatives and the Senate, has buoyed delegates gathering in Antalya. While this will be the last Cop with the US as an official party, after Trump exited the UN framework, the midterms have raised international confidence of a looming return and new, post-Trump chapter.

“This marks the beginning of the end of the Trump era,” said Mohamed Adow, director of Power Shift Africa. “His grip on Congress has been broken and hopefully paves the way for a Democratic president in two years. For everyone fighting for a livable planet, this is a moment of renewed hope.”Trump has done “enormous damage” to the climate but the midterms results, along with Luiz Inácio Lula da Silva’s recent electoral victory in Brazil, provides a major tonic, Adow said. “It opens the door to America returning to the climate fight with the seriousness its responsibility demands,” he said, adding that Cop31 would be the “perfect time to accelerate climate action and turn the tide on the Trump dark ages”.

US lawmakers arriving at Cop, all of them Democrats, are aware the world has long been subjected to wildly erratic US commitment to climate action, Casten acknowledged. “We go in with a fair amount of humility – as important as we are, the US has been an extremely unreliable partner on climate,” he said. “But going to Cop on the heels of these results feels a lot better. It can be a much more positive process now.”

Spanning two weeks of negotiations among 197 countries with an accompanying trade show-like jamboree of pavilions and side events interspersed by protests, the sprawling Cop process requires a sense of momentum. The electoral revolt in the US, the world’s largest historical emitter of greenhouse gases, should provide such a fillip, according to Susan Biniaz, a former longtime climate negotiator for the US at Cop.

“Much of the world is looking to the midterms for some kind of signal from the US electorate that they are unhappy with this administration,” Biniaz said. “This could elevate the mood. I don’t think the midterm elections will directly affect federal climate policy but they will help the spirit of the Cop.”

“There’s been a big shift since the midterms. I’m certainly more optimistic,” said Catherine McKenna, former environment minister of Canada. “Negotiations at Cop are important but it’s more important what happens at home and Trump has been incredibly disruptive. We will now have more Democrats acting on climate and talking about the solutions that will actually save people money.”But what will a thumping Democratic majority in Congress be able to do on climate? Sweeping climate legislation, similar in scale to the Inflation Reduction Act signed by Joe Biden that was subsequently gutted by Republicans, is not likely given Trump’s veto power. Still, Democrats are exploring other avenues.

Investigative and subpoena powers will be used to probe parts of the administration, such as the Environmental Protection Agency, over staff cuts and what Democrats call the “unlawful” withholding of climate and clean energy spending. Trump’s attempt to pressure Europe into taking US gas will be scrutinized, as will the vulnerability of the insurance industry to the climate crisis and concerns over the US ceding clean tech industries to China.

Democrats will dominate the budget process and will likely reverse funding cuts to environmental programs and rein in datacenters, which have become highly contentious with the US public.

Some legislation, such as the speeding up of the permitting process to allow new clean energy production and transmission, may be possible with Republican support too. The midterms also delivered striking Democratic wins at the state level, bringing new governors to states such as Texas and Georgia, meaning widespread state-based action to shift away from fossil fuels will be possible.

Much of this will likely be framed as helping tackle the rising cost of living or government corruption, rather than the climate crisis itself. Some activists have criticized Democrats for so-called “climate hushing” even as most people in the US favor the end of the fossil fuel era, but Casten said emissions reductions will matter more to the new Congress than rhetoric.

“We are going to do everything – oversight, legislation and action through the courts,” he said. “There are things around the cost of gas, or housing and insurance that are climate conversations even if we don’t mention climate. It’s our job to understand how all those things are connected but we have to talk about climate change to people in a way that is salient to them. It’s not that we don’t want to talk about climate change at all.”

Regardless of how Democrats talk about the climate crisis, its effects are mounting. Scientists have warned, repeatedly, that sluggish progress in cutting emissions has left little time to avoid disastrous impacts.

The world is already set to overshoot the internationally agreed target of limiting the global temperature rise to 1.5C, locking in turmoil for people, wildlife and ecosystems around the world, and any lingering embrace of fossil fuels by major emitters like the US will only worsen this pain. When Democrats take over Congress in January, advocates will clamor for them to rapidly make up for lost time.

“They have to do more than hold the line – this was a sweeping mandate for change,” said Rachel Cleetus, program director with the climate program at the Union of Concerned Scientists. “The science is sobering. It’s not going to wait for the next election cycle. This is a reality that people are dealing with right now and responsible lawmakers have to recognize that. The world is eager for the US to step up.”