The sores were unlike anything veteran anglers had seen before. Black, swollen and blister-like, they started appearing on fish being caught in the River Severn in early summer.

For anglers who spend many hours on the banks of the Severn around Shrewsbury, the blistering skin was yet another warning that the river, and its wildlife and habitats, are suffering.

Phil O’Callaghan, an angler, noticed the blisters on the first day of the season as he fished the Severn at Bicton Heath, north-west of Shrewsbury, this summer. “I have seen these sores in person and they look really nasty.

“I am not a scientist, I am just someone who has spent my life on the river, as an angler, a canoeist and a swimmer. I have seen it change for the worse; the river doesn’t clear any more, you cannot see the gravel, there is no weed, and at the near margins the bottom is covered in a horrible, black, smelly silt. These sores are just the latest thing we are seeing, and they are another cause for serious concern.”

O’Callaghan is one of an army of anglers, swimmers and river lovers who are working together in an attempt to stop the decline of the Severn. They have seen the devastating decline of the neighbouring Wye and they are trying to stop the same fate happening to the Severn as it, like the Wye, is subjected to excessive nutrient pollution from intensive poultry farming and record levels of raw sewage discharges from Severn Trent facilities.

Over the last two years, O’Callaghan has joined 68 other anglers along the river who dedicate hundreds of hours to monitoring the water. They have taken more than 970 samples from 70 sites to record phosphate, nitrate, dissolved oxygen, turbidity, ammonia and temperature, which they send to Bristol University for analysis. Images of the sores on fish have been sent to the Environment Agency.

Results of the Angling Trust’s 2024 water-quality monitoring report on the Severn have been shared with the Guardian. Glyn Marshall, who coordinates the monitoring, said: “The state of water in the catchment has not improved. If anything, it has got worse.

“My most recent phosphate sample in Worcester was one of the highest I have recorded. When there are periods of dry hot weather, I can see the algae blooms in the river and the bed of the river is still covered in the horrible brown gunge. The biodiversity of all the waterways is being totally compromised and we need to make sure that the health of the rivers and streams in the Severn catchment is improved for future generations.”

Analysis of the results from 52 sites for the report shows 61.5% had phosphate levels above the upper limit in the EU-derived Water Framework directive, part of Environment Agency regulations, compared with 42% in 2022-23.

Thirty-one areas, or almost 60%, had a mean average for nitrate exceeding 5ppm (parts per million) – considered the acceptable upper limit – an increase from 35% in 2022-23.

High levels of phosphate and nitrate pollute rivers. This triggers eutrophication, where the excessive plant and algal growth creates high levels of bacteria which reduces oxygen levels and kills plants and wildlife. Sewage pollution and agricultural runoff are both causes, their impacts varying from urban to rural areas.

On the Severn, sewage pollution has soared. In the three years to 2023, there were 53,072 discharges of raw sewage into the river, more than 48 each day, according to data compiled by the trust. Their duration was 429,365 hours, more than 392 hours a day.

In more rural areas, it is agricultural runoff from intensive farming that is considered to make up 70% of the excess phosphate going into the river.

Alison Caffyn, who lives in Shropshire, is a member of the volunteer army attempting to protect the Severn. She has become an expert in intensive poultry units (IPUs) after discovering a dearth of data on the impact of mega farms in the Severn valley.

“Over the years, intensive poultry units were cropping up all over Herefordshire and Shropshire and I realised there was nothing known about the issue and indeed very little research had been done, in the UK at least, about the wider impacts of intensive livestock units,” she said.

Caffyn spent years researching the units for a PhD, which saw her trawling back through Shropshire council planning records and then doing the same to track the scale of IPUs in Herefordshire, cross-referencing with satellite imagery and Environment Agency permit data.

When she turned to examine documents held by Powys council – to create a dataset for the main three counties in the Severn and Wye valleys – she discovered other researchers were doing similar work. Dr Christine Hugh-Jones and Margaret Tregear, both members of the council for the protection of rural Wales, had also been head down in planning records going back several years.

When the three women combined their research, they created an unprecedented and comprehensive dataset on the number of chickens being housed in industrial-style units in the three counties across the Severn and Wye valleys, which they update regularly. The latest data, shared with the Guardian, reveals more than 51m chickens are housed at any one time in intensive poultry units in Powys, Herefordshire and Shropshire.

Caffyn is using her research to bring a judicial review against Shropshire council’s decision to grant planning permission to another intensive poultry unit, housing 230,000 birds on nine hectares of land at Felton Butler, north of Shrewsbury.

The new intensive unit is 400 metres from an existing IPU, which appears to be in breach of Defra biosecurity regulations that there should be a 3km buffer zone between high-density poultry units.

Shropshire council approved the planning permission after the applicants promised they would transfer the manure to a third-party anaerobic digestion unit. But Caffyn says the processing of manure at an off-site anaerobic digestion unit will not cut nitrate and phosphate groundwater pollution. She points to research which says the digestate still contains all the nitrogen, phosphorus and potassium which was in the manure, and will have a negative impact when it is spread on farmland.

“We feel enough is enough. We simply cannot allow the creation of more of these giant clusters of polluting poultry units or, before we know it, the River Severn will be suffering the same pollution load as the neighbouring Wye,” she said.

Severn Trent said it had started a £450m programme to cut spills from storm overflows into the river, which was progressing at pace.

Neerja Upadhyay, head of river health enhancement at Severn Trent, said: “Since kicking off only a few months ago, our teams have been making some radical improvements that we’re already seeing benefits from.

“Increased storage on sites, repurposing existing parts of the network, installing valves and making network enhancements is all helping us make progress to reduce spills and improve river health, which is exactly what we and our customers want.”

Reefs across the north of the Great Barrier Reef have seen “substantial losses” of coral cover after a summer of extreme heat, two cyclones and major flooding, according to the first results of surveys from government marine scientists.

After the most widespread coral bleaching event seen on the world’s biggest reef system, the Australian Institute of Marine Science said one area around Cooktown and Lizard Island had lost more than a third of its live hard coral – the biggest annual drop in 39 years of monitoring.

Dr Mike Emslie, leader of Aims’ long-term monitoring program, described a “graveyard of corals” off Lizard Island, with Linnet Reef one of the worst-hit.

“It was pretty sobering,” he said. “Probably the worst single impact I have seen in 30 years. We saw dead standing coral colonies and the whole scene was a drab brown mess. As far as the eye could see was corals covered in algae.”

Aims revealed the results from in-water surveys of 19 reefs between Cairns and Cooktown carried out in recent months, where 12 reefs saw a drop in coral cover of between 11% and 72%.

The results are the first official assessment of the impact of last summer’s mass coral bleaching event, which came during a fourth global event that saw heat stress high enough to bleach more than 70% of the planet’s corals, affecting reefs in more than 70 countries.

Mass coral bleaching is caused by rising ocean temperatures driven mostly by the burning of fossil fuels.

Emslie said most of the coral death seen in the surveys had been caused by climate change-driven heat stress, but there were also impacts from two summer cyclones and flooding that saw freshwater run into the reef’s waters.

The hardest hit corals were the branching and plating Acroporas, he said, which had underpinned a growth in coral cover in recent years but had been identified as susceptible to bleaching.

The greatest heat stress last summer was seen in the reef’s southern section where scientists were on Tuesday returning from initial surveys.

Emslie said: “There is a feeling of trepidation of what the data might show [from the south of the reef].”

Between 80 and 100 more reefs are still to be surveyed between now and July 2025.

The world heritage committee, which has refused to put the reef on a list of sites in danger, urged the government to release data on coral mortality “as soon as possible”.

Coral cover in the Lizard Island-Cooktown section of the reef had fallen from 31% to 19%. Around Cairns, coral cover dropped by a third but reefs around Innisfail were stable.

Emslie said: “From what we have seen so far, the impact from these events is significant coral mortality in those areas hardest hit, although the level of mortality has been variable, and a few reefs escaped significant loss.”

He said some coral species appeared to have fared much better than others, and data so far suggested reefs on the outer shelf were much less affected. Most reefs now have moderate levels of coral cover of between 10% and 30%.

Emslie said mass coral bleaching events were “unheard of” before the late 1990s but were now happening “every other year” on the reef, and this would worsen as global heating continued. The 2024 mass bleaching was the fifth since 2016.

Richard Leck, head of oceans at World Wide Fund for Nature-Australia, said the results showed “our worst fears from this year’s coral bleaching event being realised”.

“The Great Barrier Reef can bounce back but there are limits to its resilience,” he said. “It can’t get repeatedly hammered like this. We are fast approaching a tipping point.

“Australia must commit to a federal emissions reduction target of at least 90% below 2005 levels by 2035, stop approving new fossil fuel projects and support the worldwide push for a global treaty to phase out all fossil fuels.”

Allies of the president-elect, Donald Trump, have lashed out angrily at Joe Biden for his decision to permit Ukraine to use long-range US missiles to launch attacks inside Russia for the first time, in what the Kremlin has termed an “escalation” in the war.

Key Trump surrogates, including his son Donald Trump Jr, hardline congressional Republicans, and other backers have accused Biden of seeking to spark “world war three” before Trump’s presidential inauguration in January.

“The Military Industrial Complex seems to want to make sure they get World War 3 going before my father has a chance to create peace and save lives,” wrote Donald Trump Jr on X, the social network formerly known as Twitter.

Richard Grenell, a former acting director of national intelligence during Trump’s first term, who was seen as a potential candidate for secretary of state, wrote: “No one anticipated that Joe Biden would ESCALATE the war in Ukraine during the transition period. This is as if he is launching a whole new war. Everything has changed now – all previous calculations are null and void.”

Other Republicans to sound off included the far-right congresswoman Marjorie Taylor Greene and the Utah senator Mike Lee, who said: “Joe Biden has just set the stage for World War III. Let’s all pray that it doesn’t come to this.”

A state department spokesperson, Matthew Miller, defended the decision during a press briefing on Monday, saying: “[The] American people elected Joe Biden to a four-year term, not to a term of three years and 10 months, and we will use every day of our term to pursue the foreign policy interests that we believe are in the interests of the American people.”

Discussions had been ongoing for months between the White House, the state department and European allies on whether to allow strikes into Ukraine. Currently, the decision to allow limited strikes using the US-supplied Atacms missiles would permit the Ukrainian army to target Russian military infrastructure in the Kursk region where the US has said that more than 10,000 North Korean troops have joined Russian forces preparing a counter-offensive to force Ukrainian troops out of the region.

The decision by the White House will set up a dilemma for the incoming administration on whether to immediately roll back the authorisation after Trump’s inauguration or retain it as a potential bargaining chip in the negotiations the president-elect has said he wants to hold in order to end the fighting.

While Trump and his allies have broadly denounced increasing military support and financial aid for the Ukrainian government, analysts said it was unclear whether Trump would move immediately to repeal the decision regarding long-range missiles.

“On the first day they could announce, ‘We are suspending this authorization pending a review of Ukraine policy,’” said Mark Cancian, a senior adviser with the Center for Strategic and International Studies, a thinktank based in Washington. “But that would engender a lot of criticism and revive all these stories about some deals with Putin.”

He said it was not a foregone conclusion that Trump would immediately repeal the decision. “One is just the political cost isn’t worth the gain, but Trump’s also a deal-maker, and that would be to give away something without getting anything for it … to start off with a concession is just bad negotiating tactics.”

The White House decision may also prompt European allies with similar restrictions on the use of their long-range missiles in Ukraine to follow suit. The UK is expected to supply Storm Shadow missiles for use by Ukraine on targets inside Russia following the Biden decision with Keir Starmer, the prime minister, saying at the G20 summit that the UK needed to “double down” on its support for Ukraine.

Germany has maintained its position not to supply Ukraine with long-range Taurus missiles, while the French president, Emmanuel Macron, had already said Paris was open to consider greenlighting the use of its missiles to strike on Russian soil.

Theresa Fallon, the director of the Center for Russia Europe Asia Studies in Brussels, said that there were mixed reactions among European military officials, with some worried about the potential for an escalation, while others were “happy … that Ukraine could now use the equipment without one hand tied behind their back any more. But this decision came late, very late, [Ukraine] needs to be able to defend itself, and use this equipment for what it was designed to do. But we should keep in mind it is not going to be a game changer and more equipment is needed.”

“I can’t predict what Trump will do,” she said. “But … once these things are in place, there is a momentum to continue to use them. It may be hard to put it back into the box. But on the other hand, if there is not a resupply of missiles then the use of them for targets in Russia will have run its course.”

Joe Biden headed for a photo with fellow G20 leaders in Rio de Janeiro at his final summit as US president on Monday – only to find they had already taken the picture without him.

Frustrated US officials blamed “logistical issues” for the blunder which meant that Biden missed out on the shot, along with the Canadian and Italian prime ministers.

It came during a South American tour during which Biden’s counterparts have been looking past the outgoing US president in political terms – and towards his successor, Donald Trump.

Biden’s swan song on the world stage has seen the 81-year-old try to shore up his legacy before Trump potentially takes a wrecking ball to it with his isolationist “America First” foreign policy.

World leaders including the Chinese president, Xi Jinping, Indian prime minister, Narendra Modi, and French president, Emmanuel Macron, walked down a red-carpeted ramp at Rio’s stunning bayside Museum of Modern Art to the group photo set-up.

They took to a stage, chatted and joked as they gathered to pose against the backdrop of the Brazilian city’s iconic Sugarloaf Mountain. The snap was over in a second.

Biden and the Canadian prime minister, Justin Trudeau, then came in from another direction, after a bilateral meeting on the sidelines of the summit – but it was too late and the other leaders had already dispersed.

The Italian prime minister, Giorgia Meloni, also missed the picture. She, Biden and Trudeau formed a separate huddle.

“Due to logistical issues, they took the photo early before all the leaders had arrived. So a number of the leaders weren’t actually there,” a US official said on condition of anonymity.

US officials denied that Biden missed the photo – officially for the launch of the Brazilian president Luiz Inácio Lula da Silva’s alliance to curb world hunger – to avoid appearing alongside Russia’s foreign minister, Sergei Lavrov.

Biden had earlier urged the G20 leaders to support Ukraine’s “sovereignty” in the face of Russia’s 2022 invasion.

President Vladimir Putin was conspicuously absent from the Rio summit. His arrest is sought by the international criminal court over the Ukraine war.

Donald Trump said on Monday that his administration would declare a national emergency and use the US military to carry out mass deportations of undocumented immigrants.

In an early morning social media post, Trump responded “TRUE!!!” to a post by Tom Fitton, the president of the conservative group Judicial Watch, who wrote on 8 November that the next administration “will use military assets to reverse the Biden invasion through a mass deportation program”.

Since his decisive victory, Trump has said he intends to make good on his campaign promise to execute mass deportations, beginning on the first day of his presidency. But many aspects of what he has described as the “largest deportation program in American history” remain unclear.

Trump has previously suggested he would rely on wartime powers, military troops and sympathetic state and local leaders. Such a sprawling campaign – and the use of military personnel to carry it out – is almost certain to draw legal challenges and pushback from Democratic leaders, some of whom have already said they would refuse to cooperate with Trump’s deportation agenda.

Through personnel announcements, the president-elect has put together a team of loyalists and hardliners to implement a second-term immigration crackdown.

Tom Homan, the acting director of Immigration and Customs Enforcement in his first administration, was named “border czar” with a wide-ranging remit. In a short social media post announcing the position, Trump said Homan would be “in charge of all Deportation of Illegal Aliens back to their Country of Origin”.

Also returning for a second term is Stephen Miller, a chief defender of the last administration’s most controversial immigration policies, including the use of family separation as a means of deterrence. Miller was named White House deputy chief of staff for policy and a homeland security adviser, giving him far-reaching influence over immigration policy.

Rounding out the team, he nominated the South Dakota governor, Kristi Noem, a loyalist with a long record as an immigration hardliner, to be his next secretary of the Department of Homeland Security.

Experts and advocates say a deportation campaign on the scale Trump has outlined would raise legal and logistical challenges, not to mention the soaring costs and infrastructure needed to detail and deport millions of people, many of whom have lived in the country for at least a decade, contribute to the workforce and share a household with US citizen family members.

Trump and Miller have described plans to federalize state national guard personnel and deploy them for immigration enforcement, including sending troops from friendly Republican-governed states into neighboring states with governors who decline to participate. Miller has also advocated for building large-scale detention “camps” and tents.

In his first post-election interview, Trump told NBC News that he had “no choice” but to implement a mass deportation plan, regardless of cost.

“It’s not a question of a price tag,” he said. “It’s not – really, we have no choice. When people have killed and murdered, when drug lords have destroyed countries, and now they’re going to go back to those countries because they’re not staying here. There is no price tag.”

According to an estimate by the American Immigration Council, deporting 1 million people a year would cost more than $960bn over a decade.

Trump at various points claimed he would deport at least 15 million – and even as many as 20 million – people who are in the US illegally, but the figure is unverified.

There were an estimated 11 million people living in the United States without authorization as of 2022, according to an analysis by Pew Research. Migration to the US border reached record levels in 2022 and 2023 before dropping dramatically in 2024, following stepped-up enforcement by Mexico and an asylum clampdown by the Biden administration.

It is unclear who the Trump administration would target for deportation. His campaign trail rhetoric often failed to distinguish between immigrants who have lawful status and those in the country illegally. And throughout the campaign, Trump claimed that immigrants crossing the US southern border in recent years were driving up crime, even though violent crime is down across the country and studies show immigrants commit crimes at lower rates than US citizens.

During the campaign, Trump’s team repeatedly refused to rule out deporting Dreamers, young adults brought to the US as children, hundreds of thousands of whom are allowed to live and work in the US under an Obama-era program known as Deferred Action for Childhood Arrivals (Daca).

Questions remain about how the raids would be conducted and where people would be detained. Civil liberties advocates have already raised concerns about people with lawful status or even US citizens being swept up in a sprawling dragnet.

Meanwhile, advocates have pushed back against Trump’s assertion that he enters office with a mandate to carry out mass raids. They point to data that has found most people do not support mass deportations, especially when respondents are informed about the potential impacts on the economy, the workforce and American families.

“The term strategy is clear, foment fear, panic and chaos into our communities, because as bullies, this is what they thrive on,” Greisa Martínez Rosas, the executive director of United We Dream Action, a network of groups that advocate for Dreamers said during a post-election debrief. She added: “Trump may be re-elected, but he does not have a mandate to come into and rip apart our communities.”

Countries meeting in Azerbaijan to discuss a new global financial settlement for tackling the climate crisis must “cut the theatrics” and get down to serious business, the UN has said.

The UK and Brazil have been drafted in to try to break a logjam at the Cop29 climate summit, which entered its second week on Monday with no agreement in sight on the key issue of how to channel at least $1tn a year to developing countries.

Poor nations need the money to cut greenhouse gas emissions and cope with the impacts of extreme weather. Rich countries stand accused of failing to come up with the cash to help them.

Officials from nearly 200 countries worked last week to draw up the text of a potential deal, but many countries have sent ministers – with decision-making powers – to the Azerbaijani capital, Baku, only for the second half of the fortnight-long meeting.

Simon Stiell, the UN’s climate chief, told the conference: “Ministers who have just arrived need to roll up their sleeves and dive into the hardest issues. Bluffing, brinksmanship and premeditated playbooks are burning up precious time. So let’s cut the theatrics and get down to the real business this week.”

He reminded rich countries that it was in their interest to help the poorest, which are suffering from the impacts of extreme weather but have done little to cause global heating. “Climate finance is not charity,” he said. “It is 100% in every nation’s interest to protect their economies and people from rampant climate impacts.”

Mukhtar Babayev, Azerbaijan’s environment minister and the president of the talks, said: “Politicians have the power to reach a fair and ambitious deal. They must deliver on this responsibility. They must engage immediately and constructively. The highest possible level of ambition is indeed difficult, and it requires courage. Colleagues, now is the time to be brave.”

The UK and Brazil will work with countries to help find a “landing zone” of agreement. Bones of contention include how much developed countries should provide from their own budgets and how much should come from the private sector; how to expand the number of contributors, from the established industrialised countries to include emerging economies such as China and petrostates such as Saudi Arabia; and by what deadline the target should be met.

Australia’s climate and energy minister, Chris Bowen, is charged with guiding the finance track of the talks. He and Yasmine Fouad of Egypt are the “ministerial pairing” in charge of the “new collective quantified goal” (NCQG) negotiations.

Bowen told the Guardian the process was like “a four-dimensional jigsaw”. The NCQG must include numbers, on the amount of finance developing countries can expect and where it should come from, including developed countries’ aid budgets, development banks such as the World Bank, and the private sector.

The structure of an agreement is also key, including deadlines for meeting the goals, and rules on which countries can access the funding and how. These factors were “intrinsically linked, so you can’t solve one without the other”, he told the Guardian.

“Those four things – the big three plus accessibility – is a jigsaw puzzle. A four-dimensional jigsaw puzzle being constructed on a tight timeline, with 198 parties,” Bowen said.

Sherry Rehman, a member of Pakistan’s senate, was the country’s environment minister when devastating floods submerged one-third of Pakistan in August 2022, displacing an estimated 8 million people and causing damage costing tens of billions of dollars.

She urged world leaders to “keep an eye on the big picture” rather than indulging in petty bickering over who was to blame. “We’re here for life and death reasons,” she told the Guardian in an interview. “We’re one of the most climate-vulnerable countries in the world. So we can’t walk away.”

Mohamed Adow, the director of the thinktank Power Shift Africa, said developed countries must take responsibility for having caused the climate crisis through more than a century and a half of reliance on fossil fuels.

“The climate finance goal needs to include both a public finance provision and a mobilisation goal of new and innovative sources,” he said. These sources could include a wealth tax, now under discussion at the G20 in Brazil, and taxes on high-carbon activities such as frequent flying.

“The public, grant-based component of the new finance goal must be big enough to give confidence to the developing countries who are currently in debt distress,” Adow added. “For them private finance, which needs to be repaid with interest, is just a recipe for more debt.”

Poor countries needed help to make their infrastructure, both physical and social, more resilient to the impacts of extreme weather. Private companies were unlikely to provide this, so governments must step in, Adow said.

“These countries can’t afford to leave Baku without assurances of public, grant-based finance to address their adaptation needs and help deal with the loss and damage caused by the climate crisis,” he said.

Throughout the UN climate talks in Baku, Azerbaijan, in recent days, US officials have maintained a studiously sunny disposition, saying that the Republican president-elect, Donald Trump, will not derail climate progress.

The US climate envoy, John Podesta, said the fight “for a cleaner, safer” planet will not stop under a re-elected Trump even if some progress is reversed. The energy secretary, Jennifer Granholm, said: “The absence of leadership in the White House does not mean that this energy transition is stopped.” And Joe Biden’s climate and energy assistant, Jacob Levine, told reporters that the president’s climate policies had sparked an unstoppable clean energy “revolution”.

In the absence of federal climate policy, they have argued, states will continue the push to zero out emissions. And the historic climate-related subsidies in the Inflation Reduction Act, they have said, will continue to spur decarbonization efforts from the private sector. On Monday, US officials reinforced this view with a plan for continued private sector-led emissions reduction in manufacturing.

“Climate change won’t be solved by one president, but climate action will not be stopped by one president,” the Massachusetts senator Ed Markey told reporters on Saturday.

Decarbonization, Markey said, was even taking place in Republican states, thanks to Biden’s green subsidies. “The green revolution is blue and red,” he said.

But Republicans have come to Cop29 with a different message. In a sometimes surreal Saturday press conference where they cracked jokes about US sports teams before an international audience, four Republican members of Congress aggressively argued for increasing oil and gas production; even coal, they argued, should maintain its place in the energy system.

“With technology, we can solve a lot of these problems without just banning fossil fuels,” said Representative Morgan Griffith, who represents a coal country district in Virginia. “An area that has natural resources should not be penalized for not looking at the opportunity to have a cleaner world.”

Representative August Pfluger, whose Texas district covers the oil-rich Permian Basin, said Trump’s re-election indicates an “overwhelming support” for the former president’s call to “restore America’s energy dominance and lead the world in energy expansion”.

And when asked by the Guardian in the halls of Cop29 if he would support Trump’s pledge to pull the US out of the Paris agreement, Pfluger responded by talking about energy: “We definitely want to see affordable, reliable energy provided throughout the world.

“Inflation has been very difficult on people, and we have to take a realistic look about the types of energy and the innovation for energy freedom throughout the world,” said Pfluger, who is leading the House of Representatives’ delegation to the UN climate summit. “Many countries would say that some of the tenets [in the accord] have actually been a massive competitive disadvantage and have pushed up prices everywhere around the world.”

In the weeks leading up to his second inauguration, Trump appears to have doubled down on his crusade against climate action. This week, he tapped a former fracking executive to head up his energy department, a Republican who arranged an infamous meeting between Trump and oil bosses to lead his interior department, and a former congressman who has a score of just 14% from the League of Conservation Voters to lead the Environmental Protection Agency.

Still, Democratic officials at Cop29 say that the Inflation Reduction Act’s hundreds of billions of dollars in clean energy incentives and tax breaks are durable.

At Saturday’s press conference, Pfluger did indicate that Congress would probably preserve some of its provisions. “If there are pieces of the IRA that help support lowering American energy costs, helping Americans, helping our partners and allies have access to affordable, reliable energy, then I bet that those will stay in place,” Pfluger said.

But the US should include fossil fuels in a “best of the above” energy strategy, said Republican Michigan representative John James at the press conference. And the overall strategy, he said, should be “innovation, not regulation”.

Harjeet Singh, a director at the Fossil Fuel Treaty Initiative, a proposed agreement for a concrete phaseout of coal, oil, and gas, attributed the Republicans’ message to a “toxic alliance between polluting corporations and complicit political leaders.”

A key aim for Cop29 negotiators is to establish a new and expanded global goal for climate finance to help poor countries cope with disasters and draw down their emissions. Over the weekend, the White House announced that the US surpassed its goal of providing $11bn a year in climate financing.

Trump during his first term proposed eliminating the US’s climate finance commitments, but was shot down by the Senate.

When asked on Saturday if he would support zeroing out US climate aid, Pfluger deflected, but did not rule out the possibility. “What we want to do … is to unleash American energy, to unleash innovation throughout the world that benefits in a connected world from affordable clean reliable energy,” he said.

Climate finance, he said, should only go to projects that focus on slashing energy costs. “If something is not congruent or not in support of lowering energy costs while reducing emissions, you can bet that this Congress is going to look at that,” he said.

International leaders at Cop29 have railed against Trump’s stance against climate action and his pledge to exit the Paris agreement. As the world’s largest economy and top contributor to historic emissions, the US had an “ethical responsibility” to lead the climate fight, said Ambassador Dr Pa’oleilei Luteru, chair of the Alliance of Small Island States, an intergovernmental organization of low-lying coastal and small island countries.

“The US doesn’t live on a different planet,” he said.

Sherry Rehman, a member of the Pakistan senate and former Pakistan climate change minister, said the US pulling out of the Paris accord would be a “blow to the whole shape of the climate negotiations process”.

“The United States casts a huge geopolitical and development and leadership shadow still on the world,” she said. “It has a gravitational pull.”

But Trump cannot singlehandedly derail UN climate negotiations, leaders have said.

“The Paris agreement is a robust process,” Hilda Heine, president of the Marshall Islands, said in a Wednesday press conference.

Jacob Levine, a Biden climate adviser, told reporters this week that Biden had set into motion a “deeply shared and integrated vision” for the clean energy transition that has led countries such as the UK, Canada, and Australia to take “a page out of the US government playbook”.

But Trump’s vision also appears to have spread, with Argentina’s far-right president, Javier Milei, reportedly considering removing his country from the Paris climate accord.

US officials’ relentless optimism at Cop29 has been a source of frustration for some. In an intimate meeting with reporters on Saturday, one journalist asked the Democratic Rhode Island senator and climate hawk Sheldon Whitehouse why it was difficult for officials to say that Trump’s presidency is a threat to climate action.

“The US election will have a negative climate impact,” Whitehouse said. “That’s not only easy to say, it’s obvious.”

Some of the earliest examples of purpose-built social housing in the UK can still be found tucked away along central London’s more affluent streets. Built in Edwardian baroque style, the Sutton Dwellings in Chelsea are perhaps an unlikely site for an innovative scheme at the new frontier of Britain’s low-carbon journey.

This winter more than 80 of the estate’s flats will be warmed by heat pumps that tap the warmth of the earth well below the streets of central London.

The scheme’s 27 boreholes burrow deep into the ground directly beneath the estate to where piped water is warmed and fed to a network of “shoebox” heat pumps in a cupboard in each flat. Here, each heat pump – roughly the size of a gas boiler – tops up the heat of the water pipes so that each household can control their own heating, setting it to their preference or using thermostats.

The scheme was completed in late autumn as part of a refurbishment of the more than 100-year-old block of flats, confounding the myths around the UK’s heat pump roll out, such as claims that they do not work in older buildings. It aims to show that heat pumps are not only for newer buildings and that ground source heat pumps are not only for homes with extensive outdoor space.

The developer, Kensa, has completed schemes across the south-east of England, installing shoebox heat pumps in 273 flats across multiple 1960s tower blocks in Thurrock, Essex, and in more than 400 flats across eight tower blocks owned by Enfield council. The Sutton Dwellings project proves that prewar housing can benefit, too.

“Often you see claims heat pumps don’t work, they aren’t suitable for older buildings, there isn’t enough space to install ground source heat pumps in cities,” said Stuart Gadsden, a commercial director at Kensa. “Hopefully, this project can serve as a blueprint for other social housing providers with properties that need decarbonising.”

Heating the UK’s 28m homes accounts for almost a fifth of the UK’s greenhouse gas emissions, and as temperatures drop this winter, ministers will face rising questions over its plan to tackle this area of the economy. The government is expected to set out the full details of a major funding plan in the coming weeks.

Air source heat pumps are expected to play a big role; according to some forecasts, the outdoor heating units will replace gas boilers in more than 40% of homes. A fifth of homes could have a ground source heat pump for heating and hot water. Kensa believes its network approach may help to upgrade social housing and tower blocks across the country, and could even be adapted to meet the heating needs of entire streets, with boreholes prepared in advance for homes to connect to when they choose to upgrade their heating system.

Making low-carbon heating an affordable – and desirable – alternative to traditional gas boilers will be key to the success of the government’s ambition to create a net zero economy by 2050.

Less than two miles from Sutton Dwellings at the Lillington Gardens estate in Pimlico, residents are deeply sceptical. Here, leaseholders have been warned by Westminster city council that they could face bills of between £30,000 and £66,000 each to replace its buckling heat network. The council has proposed a low-carbon scheme that would cost up to £185m and help the local authority reach its target of becoming net zero by 2030.

In the 1960s, the Lillington heat network was once at the vanguard of low-carbon home heating, making use of the waste heat emitted by miles of underground pipes from the nearby Battersea power station. Since then the network has come to rely on centrally located gas boilers and has fallen into disrepair, leaving residents to battle burst pipes, hot water leaks and sewage spills.

The Labour-led council has blamed “historic underinvestment” for the failure of the heat network and said it is costing £3.5m a year in insurance to manage the “constant leaks that have negatively affected the lives of residents”. The councillor Liza Begum said the council was working with residents to urgently find a long-term solution, and reduce the costs for residents and leaseholders.

The council has joined the Greater London Authority and London councils in a pan-London consortium bid for government funding that aims to help provide low-carbon heating projects and heating upgrades to low-income homes in England.

Huge funding opportunities have been promised by the Labour government but the details of how such schemes will work are not known. The Treasury used its first budget since Labour came to power to promise £3.4bn for the warm homes plan; it is considered the first phase of an ambitious £13.2bn commitment over this parliament to increase the grants available to homes that choose to swap their gas boilers for heat pumps and to upgrade the energy efficiency of Britain’s draughtiest housing stock.

Households connected to communal or district heat networks are often paying twice as much for their heat as those with their own gas boiler, according to Heat Trust. The consumer champion for heat network users has urged the government to help lower their costs by bringing in two reforms: first to extend the energy price cap to include homes connected to a heat network, and second, to provide support to help cover the costs of repairing old heat networks.

Stephen Knight, the chief executive of the Heat Trust, said: “Heat networks will have an increasing role to play in how we heat our homes in cities and towns in the coming decades, as we move away from a reliance on gas boilers. However, we currently see too many examples of poorly designed, inefficient heat networks that generate heat using expensive commercial energy contracts. This often results in high heating bills for their residents as the end consumers.”