The chief executive of the American chip maker Nvidia visited Beijing on Thursday, days after the US issued fresh restrictions on sales of the only AI chip it was still allowed to sell to China.

Jensen Huang’s surprise visit was on the invitation of a trade organisation, according to a social media account affiliated with state media.

The official broadcaster China Central Television said Huang met Ren Hongbin, the head of the China Council for the Promotion of International Trade, where he said he hopes “to continue to cooperate with China”.

China Daily, the ruling Communist party’s official English-language outlet, published a photo of Huang in the capital, saying the trip came “three months after pledging to continue cooperation with #China during his last visit”. It added the hashtag #OpportunityChina, which it has previously used in posts promoting US-China exports.

The visit caps a tumultuous week for Nvidia. The US restrictions, announced on Tuesday, apply to shipments of its H20 datacentre GPUs, a lower-powered version of other Nvidia chips, which was designed specifically to comply with Biden-era restrictions on sales to China.

The US government, which is battling China in the race for AI supremacy, told Nvidia the new rules were designed to address the risk that its products might be “used in, or diverted to, a supercomputer in China”.

The company has said the new controls will cost it $5.5bn (£4.2bn) in earnings. Shares of the company slumped about 7% on Wednesday.

US restrictions on tech supplies to China, as well as extensive tariffs on foreign imports, have put enormous pressure on the tech industry, and Nvidia’s stock is among many in the sector to have fallen steeply in recent weeks. Trump has threatened separate tariffs on the global semiconductor industry, in an effort to bring manufacturing bases on to US soil.

The fresh Nvidia chip restrictions came a day after the semiconductor company said it would build up to $500bn worth of AI infrastructure in the US over the next four years.

Nvidia designs its chips but outsources its production to contractors such as Taiwan Semiconductor Manufacturing Company. TSMC has also pledged massive investment projects in the US, which Trump said would exempt it from the tariffs. The White House said in a statement that Nvidia’s decision was “the Trump effect in action”.

The Financial Times reported that Huang also met the DeepSeek founder, Liang Wenfeng, in Beijing, to discuss new chip designs for the AI company that would not trigger the new US bans. In January the shock emergence of DeepSeek, an AI chatbot seemingly much more advanced than existing rivals but developed for far less investment, sent the tech industry into a tailspin, and a global sell-off of shares.

The US House of Representatives’ China committee has written to Nvidia asking it to explain whether DeepSeek obtained export-controlled chips to power its artificial intelligence app and, if so, how. It has said the app poses a “profound threat” to national security.

Huang has said publicly that Nvidia will balance legal compliance and technological advances under Trump but has promised that nothing will stop the global advance of AI. “We’ll continue to do that and we’ll be able to do that just fine,” the Taiwan-born entrepreneur told reporters last year.

Huang’s arrival in Beijing caused a stir on Chinese and Taiwanese social media. He’s a celebrity figure in Taiwan; on recent visits large crowds of fans greeted him and there was breathless reporting of his itinerary.

Trump’s tariffs have sparked chaos in global markets and among governments, including US allies. After announcing a range of tariffs against different countries, which he accused of “ripping off” the US by having a trade surplus, Trump later drew them all back to 10% (except China, which he kept at 145%) for a 90-day pause. He claimed governments were begging to negotiate with the US to rewrite trade agreements.

On Thursday he posted on social media that there had been “big progress” in talks with Japan the previous day. Japan had not expected the US president to get involved in Wednesday’s talks, viewing them as a preliminary, fact-finding mission, a sign that Trump wants to keep tight control over negotiations with dozens of countries expected over the coming days and weeks.

Japan’s prime minister, Shigeru Ishiba, warned that the talks “won’t be easy”, but he said the president had “expressed his desire to give the negotiations … the highest priority”.

Additional reporting by Jason Tzu Kuan Lu

Prime Minister Mark Carney said the key question in Canada’s upcoming election is who is best to deal with Donald Trump as he faced his Conservative rival in a French-language leaders’ debate on Wednesday.

Opposition Conservative leader Pierre Poilievre said during the debate Canada needs change after a decade of Liberal party rule and Carney is just like his predecessor, Justin Trudeau. Carney responded: “Mr Poilievre is not Justin Trudeau. I’m not Justin Trudeau either. In this election the question is who is going to face Mr Trump.”

The exchange was the first between the two men since Carney was elected Liberal leader in March.

Trump’s trade war and threats to make Canada the 51st state have infuriated Canadians and led to a surge in Canadian nationalism that has bolstered Carney’s Liberal party poll numbers ahead of the 28 April vote.

The debate took place in Montreal, the largest city in predominantly French-speaking Quebec. The province has 78 of the 343 seats in the House of Commons and is usually regarded as one of the keys to victory.

Poilievre is imploring Canadians not to give the Liberals a fourth term. He hoped to make the election a referendum on Trudeau, whose popularity declined toward the end of his decade in power as food and housing prices rose and immigration surged.

But Trump attacked, Trudeau resigned and Carney, a two-time central banker, became Liberal party leader and prime minister after a party leadership race.

When asked about Trudeau at a news conference after the debate, Carney said: “One of the differences, there are many, but one of the differences between the two of us is that I put much more emphasis on the economy, on growing the economy.

“In fact in this circumstance that we are in, given the scale of the crisis, I would say relentless focus on growing the economy.”

Yves-François Blanchet of the separatist Bloc Québécois, whose party is losing support to Carney’s Liberals in Quebec, agreed with the Conservatives’ call for change, saying the Liberals are the same party, the same ministers and the same lawmakers and a new leader does not change that.

But public opinion too has changed. In a mid-January poll by Nanos, Liberals trailed the Conservative party by 47% to 20%. In the latest Nanos poll released on Wednesday, the Liberals led by eight percentage points. The January poll had a margin of error 3.1 points while the latest poll had a 2.7-point margin.

The French debate was moved up by two hours to minimise a conflict with a Montreal Canadiens hockey game. The NHL team faced off against the Carolina Hurricanes at 7pm ET, in a game that could clinch them a spot in the Stanley Cup playoffs.

This isn’t the first time NHL hockey has elbowed its way onto the campaign trail. During the 2011 election, former Bloc leader Gilles Duceppe asked for a debate to be postponed due to a Canadiens hockey game, and his request was granted.

The English language debate is being held on Thursday evening.

With Associated Press and Reuters

UK officials are tightening security when handling sensitive trade documents to prevent them from falling into US hands amid Donald Trump’s tariff war, the Guardian can reveal.

In an indication of the strains on the “special relationship”, British civil servants have changed document-handling guidance, adding higher classifications to some trade negotiation documents in order to better shield them from American eyes, sources told the Guardian.

The White House has upended global financial markets and torn up key relationships, with unpredictable and rapidly changing taxes on trading partners including China, the EU and the UK.

Officials were told that the change in protocols was specifically related to tensions over important issues on trade and foreign policy between Washington and London, sources said.

Keir Starmer has prioritised striking a trade deal with Washington, opting not to retaliate over Trump’s decision to impose 10% tariffs on goods exported to the US, and 25% tariffs on UK car and steel exports, instead offering concessions on areas including digital taxes and agriculture.

JD Vance said on Tuesday he believed a mutually beneficial US-UK trade deal was within reach. The US vice-president said officials were “certainly working very hard with Keir Starmer’s government” on a trade deal, adding that it was an “important relationship”.

“There’s a real cultural affinity,” Vance said. “And, of course, fundamentally, America is an anglo country. I think there’s a good chance that, yes, we’ll come to a great agreement that’s in the best interest of both countries.”

However, behind the scenes concern is growing over the vulnerability of UK industries and companies to Trump’s “America first” agenda.

Before Trump’s inauguration, UK trade documents related to US talks were generally marked “Official – sensitive (UK eyes only)”, according to examples seen by the Guardian, and officials were allowed to share these on internal email chains. This classification stood while British officials attempted to negotiate with Joe Biden’s administration, even after a full-blown trade deal was ruled out by the White House.

Now, a far greater proportion of documents and correspondence detailing the negotiating positions being discussed by officials from No 10, the Foreign Office and the Department for Business and Trade come with additional handling instructions to avoid US interception, with some classified as “secret” and “top secret”, sources said. These classifications also carry different guidance on how documents may be shared digitally, in order to avoid interception.

Companies with commercial interests in the UK have also been told to take additional precautions in how they share information with the trade department and No 10, senior business sources said. These include large pharmaceutical companies with operations in the UK and EU.

A Department for Business and Trade spokesperson said: “The US is an indispensable ally and negotiations on an economic prosperity deal that strengthens our existing trading relationship continue.”

Wider questions have been asked about whether the special relationship between the UK and US can withstand increasingly divergent policies on Russian hostility, as well as deep criticisms of Nato and defence collaboration. On trade, pressures are mounting in sensitive areas such as car manufacturing and pharmaceuticals.

Other reports suggest the European Commission has also changed its perspective on the risks of sensitive or secret information being intercepted by the US. Commission employees have been issued with burner phones if they are visiting the US, the Financial Times has reported.

So close has the UK and US position been on defence and security in recent years that secure government material is sometimes marked “UK/US only”, or given a “Five Eyes” marking, in reference to the intelligence-sharing collective made up of the US, UK, Australia, New Zealand and Canada. So far, the Guardian has only established a change in document-handling related to trade discussions.

Trump’s plan to reboot domestic industry, including in automotive and pharmaceutical manufacturing, has caused consternation among foreign governments keen to protect domestic industries and jobs while trying to strike trade deals to protect against heavy tariffs.

Trump has sought to defend his decision to put vast tariffs in place, saying there would be a “transition cost” from his policies.

The US president also said he would “love” to make a deal with China and that, in his view, he and the Chinese president, Xi Jinping, would “end up working out something that’s very good for both countries”.

In a move regarded by some observers as an attempt to soothe market reactions, including a rise in US government borrowing costs, Trump said last week that he would delay further tariffs for 90 days. The European Commission president, Ursula von der Leyen, said the EU would also delay its response to US tariffs.

Until July, the EU will face a 10% duty on exports to the US, rather than the 20% “reciprocal tariff” rate that was in force for a matter of hours, until Trump’s reversal last Wednesday. US duties of 25% tariffs on steel, aluminium and cars are still in place, however.

Despite suggestions that Trump may be chastened by the markets’ volatile response to his trade policies, the president’s incremental steps have increased duties on Chinese imports to 145%. China responded on Friday by announcing it would increase tariffs on US goods to 125%. The announcement from the Chinese commerce ministry also suggested that it would not pursue higher tariffs in any further retaliatory steps against the US, adding that “at the current tariff level, there is no market acceptance for US goods exported to China”.

“If the US continues to impose tariffs on Chinese goods exported to the US, China will ignore it,” it said, flagging that there were other countermeasures to come. Xi, meanwhile, urged the EU to resist Trump’s “bullying”.

Donald Trump has declared that Harvard University should no longer receive federal funds, calling it a “joke” that “teaches hate and stupidity”, while his administration said the pre-eminent US university could lose its ability to enrol foreign students.

Harvard made headlines on Monday by becoming the first university to stand up against a series of onerous demands from the Trump administration, setting the stage for a showdown between the federal government and one of the US’s most prestigious institutions.

The Trump administration swiftly retaliated by announcing it would freeze more than $2bn in multiyear grants and contracts with the university. On Wednesday it was also reported by CNN that the IRS was planning to take away Harvard’s tax-exempt status.

Numerous Democratic politicians and top universities across the country have rallied in support of Harvard, but the Trump administration has doubled down, threatening to strip Harvard of its tax-exempt status and insisting that the university apologize.

The Department of Homeland Security (DHS) said late on Wednesday that Harvard would lose its ability to enrol foreign students if it did not meet demands the Trump administration demands to share information on some visa holders. The department’s secretary, Kristi Noem, also announced the termination of two DHS grants to Harvard totalling more than $2.7m.

Noem said she wrote a letter to the university demanding records on what she called the “illegal and violent activities” of Harvard’s foreign student visa holders by 30 April. “And if Harvard cannot verify it is in full compliance with its reporting requirements, the university will lose the privilege of enrolling foreign students,” she said in a statement.

A spokesperson for Harvard said it was aware of Noem’s letter and that the university stood by its statement earlier in the week to “not surrender its independence or relinquish its constitutional rights”, while saying it would comply with the law.

As part of an ongoing government review of various universities over allegations of antisemitism following the student-led campus protests against the war in Gaza last year, the Trump administration sent a letter to Harvard University on Friday outlining a list of demands it must meet in order to “maintain Harvard’s financial relationship with the federal government”.

It demanded Harvard close all diversity, equity and inclusion programs; share various admission details with the government; report foreign students who commit conduct violations to federal authorities; commission an outside party to audit each academic department to make sure the student body, faculty, staff and leadership is “viewpoint diverse”; and more.

On Monday, Harvard’s president, Alan Garber, responded that the university would not yield to the government’s demands, describing them as “an attempt to control the Harvard community”.

“The University will not surrender its independence or relinquish its constitutional rights,” he said. “The administration’s prescription goes beyond the power of the federal government. It violates Harvard’s first amendment rights and exceeds the statutory limits of the government’s authority under Title VI. And it threatens our values as a private institution devoted to the pursuit, production, and dissemination of knowledge.”

He added: “No government – regardless of which party is in power – should dictate what private universities can teach, whom they can admit and hire, and which areas of study and inquiry they can pursue.”

Other universities responded quickly. In a statement on Tuesday, the acting president of Columbia University said that it would “reject any agreement in which the government dictates what we teach, research, or who we hire”.

This comes after Columbia agreed to several demands from the administration last month after the White House pulled $400m of research grants and other funding from the school over its handling of the protests against the war in Gaza.

“To put minds at ease,” Columbia’s acting president, Claire Shipman, wrote on Tuesday, “though we seek to continue constructive dialogue with the government, we would reject any agreement that would require us to relinquish our independence and autonomy as an educational institution.”

The president of Stanford University, Jonathan Levin, and the school’s provost, Jenny Martinez, also released a statement in response to Harvard’s decision, praising the university.

“Universities need to address legitimate criticisms with humility and openness,” Levin and Martinez wrote. “But the way to bring about constructive change is not by destroying the nation’s capacity for scientific research, or through the government taking command of a private institution.”

Christopher Eisgruber, the president of Princeton University, also weighed in. “Princeton stands with Harvard,” he wrote. “I encourage everyone to read President Alan Garber’s powerful letter in full.”

So did Barack Obama. “Harvard has set an example for other higher-ed institutions – rejecting an unlawful and ham-handed attempt to stifle academic freedom, while taking concrete steps to make sure all students at Harvard can benefit from an environment of intellectual inquiry, rigorous debate and mutual respect,” the former president wrote. “Let’s hope other institutions follow suit.”

Maura Healey, the governor of Massachusetts, where Harvard is located, also praised the university for “standing against the Trump Administration’s brazen attempt to bully schools and weaponize the US Department of Justice under the false pretext of civil rights”.

In response, Trump threatened Harvard’s tax-exempt status. Most universities in the US are exempt from federal income tax under the US tax code because they are considered to be “operated exclusively” for public educational purposes.

Later on Tuesday, the White House press secretary, Karoline Leavitt, told reporters that Trump “wants to see Harvard apologize”.

Then on Wednesday morning, Trump took to social media again to attack Harvard on his social media platform, Truth Social.

“Harvard is a JOKE, teaches Hate and Stupidity, and should no longer receive Federal Funds,” Trump wrote in the lengthy post. “Thank you for your attention to this matter!”

Reuters contributed to this report

The world’s largest meat company, JBS, looks set to break its Amazon rainforest protection promises again, according to frontline workers.

Beef production is the primary driver of deforestation, as trees are cleared to raise cattle, and scientists warn this is pushing the Amazon close to a tipping point that would accelerate its shift from a carbon sink into a carbon emitter. JBS, the Brazil-headquartered multinational that dominates the Brazilian cattle market, promised to address this with a commitment to clean up its beef supply chain in the region by the end of 2025.

In a project to understand the barriers to progress on Amazon deforestation, a team of journalists from the Guardian, Unearthed and Repórter Brasil interviewed more than 35 people, including ranchers and ranching union leaders who represent thousands of farms in the states of Pará and Rondônia. The investigation found widespread disbelief that JBS would be able to complete the groundwork and hit its deforestation targets.

“They certainly have the will to do it, just as we have the will to do it,” said one rancher. But the goal that all the cattle they bought would be deforestation-free was unreachable, he said. “They say this is going to be implemented. I’d say straight away: that’s impossible.” The problem of illegal cattle laundering would also not be resolved in time, said many, while another interviewee said land ownership issues meant quite simply that the deadline was “impossible”.

JBS told the Guardian that it contested the conclusions. “Drawing inferences and conclusions from a limited sample of 30 farmers while disregarding that JBS has over 40,000 registered suppliers is entirely irresponsible,” the company said in a statement. It said that “while the sector-wide challenges are significant and larger than any one company can solve on its own, we believe JBS has an in-depth and robust series of integrated policies, systems, and investments that are making a material and positive impact on reducing deforestation risks.”

To hit its targets, JBS needs to register all its direct and indirect suppliers and ensure none of the meat it buys from the Amazon is from cattle that has grazed on deforested land. It has established a network of “green offices” to provide free consultation to ranchers on how to comply with the three- to six-month process of regularisation, which involves drawing up a plan to plant more trees, withdrawing from contested territory, or making other environmental remediations. Then details will go into the JBS database, which continually monitors farms using artificial intelligence, and owners will be contacted if they fail to meet their obligations. In Pará, the company is also working with the state government on an ear-tagging scheme that would track the state’s entire herd of 26 million cattle by 2026.

The Pará state governor, Helder Barbalho, who has supported the traceability plan, expects JBS to meet its deadline, but he acknowledged there had been resistance and that small farmers in particular would need more support. He said the Bezos Earth Fund had committed 143m reais to this task: “We are still mobilising resources so that we can finance this policy that is very important for us to present to livestock farmers.”

But ranchers and rancher unions interviewed by the Guardian and its partners said that technical hurdles and uncertainties over land ownership – many ranches were created by invading public land – stood no chance of resolution by the company’s self-imposed deadline.

Adelosmar Antonio Orio, known as Ticão, who works for the Tucumaã-Ourilaãndia Union of Rural Producers, said the logistical challenges, such as ranchers needing special equipment including ear trackers and satellite internet systems, would make the scheme impossible to complete before the year-end deadline. “Not even they [JBS] know how this traceability is going to be implemented,” he said. Others argued that new small- and medium-sized producers were being asked to bear most of the burden of the new system and that JBS and the government had not done enough to explain the new tracking system and provide the technological support needed to make it work.

The thorny subject of land ownership would also be impossible to resolve, argued many, including Cristina Malcher, the president of the Commission of Women in Agribusiness, a national advocacy body for women in agriculture. “The deadline of 2025 is impossible to meet, because if you don’t know who owns the land, then you don’t have environmental regularity,” Malcher told the Guardian.

Ticão agreed. “By the end of the year, we need to resolve all the land problems, all the environmental problems.” Could it be done in time? “Definitely not,” he said. His union colleagues expressed similar disbelief that the deadline could be met.

The investigation also spoke to indirect suppliers who openly admitted to using middlemen to clean up the environmental record of their livestock, a practice known as cattle laundering. Several producers predicted that a new tracing system would lead to new loopholes, such as slaughtering the cattle elsewhere and then selling the meat – rather than live cattle – at a low price to JBS.

JBS has not mapped its entire supply chain, due under its deforestation commitments by the end of this year. But the company said: “JBS has already enrolled the equivalent of over 80% of its annual cattle purchases on to a blockchain-enabled, web-based transparent farming livestock platform.”

JBS has previously been linked to deforestation on a number of occasions, and the New York attorney general, Letitia James, filed a lawsuit last year accusing the company of misleading consumers with its climate goals in an effort to increase sales. A bipartisan group of 15 US senators urged the Securities and Exchange Commission to reject JBS’s application for a share listing. “Dozens of journalistic and NGO reports have shown that JBS is linked to more destruction of forests and other ecosystems than any other company in Brazil,” they wrote in an open letter.

JBS told the Guardian: “The challenges of addressing illegal deforestation on cattle operations that span millions of farms across hundreds of thousands of square kilometresare significant.” It detailed its response, which includes zero tolerance for deforestation sourcing policy, state-of-the-art supply chain monitoring, free technical assistance for producers to help regularise their farms, and the JBS Fund for the Amazon, which finances projects focused on the sustainable development of the Amazon biome.

The company also said: “JBS works with farmers, ranchers and partners across the food system to develop solutions that support a growing global population while optimising resources and reducing agriculture’s environmental impact. Cattle raising in the Amazon is undergoing a sectoral transformation, and one company cannot solve all the industry’s challenges.”

Brazil is the biggest exporter of beef in the world, and more than 40% of its vast 240m-cattle herd is raised in the Amazon region. As a result, swathes of the nature-rich rainforest are being cleared and burned to create pasture.

This is pushing Amazon destruction close to a point of no return, prompting environmentalists and consumer groups to demand deforestation-free meat products. Governments, meat suppliers and retailers have promised to clean up their act, but one of the biggest hurdles is a complex and obscure supply chain that can hide the origins of meat products.

From birth to slaughter, most of the cattle raised in the Amazon are moved around multiple farms. Before sale to big meatpacking companies such as JBS (the world leader), they may spend up to 75% of their lives on indirect supplying ranches. This system creates loopholes and blind spots in oversight, which allow “cattle laundering”, as it is known, where cattle from illegal or deforestation-linked farms are mixed into the supply chain. Farms that have been linked to deforestation may be embargoed by the Brazilian environment agency IBAMA.

Global consumers of Brazilian beef cannot know for sure whether their burgers and steaks caused destruction of the rainforest until there is a way to track the entire supply chain, which can be understood as follows:

How beef is ‘laundered’ in the Amazon

Toothpaste can be widely contaminated with lead and other dangerous heavy metals, new research shows.

Most of 51 brands of toothpaste tested for lead contained the dangerous heavy metal, including those for children, or marketed as green. The testing, conducted by the Lead Safe Mama non-profit, also found concerning levels of highly toxic arsenic, mercury and cadmium in many brands.

About 90% of toothpastes contained lead, 65% contained arsenic, just under half contained mercury, and one-third had cadmium. Many brands contain a number of the toxins.

The highest levels detected violate some federal and state limits in the US, though the thresholds have been roundly criticized by public health advocates for not being protective – no level of exposure to lead is safe, the federal government has found.

“It’s unconscionable – especially in 2025,” said Tamara Rubin, Lead Safe Mama’s founder. “What’s really interesting to me is that no one thought this was a concern.”

Lead can cause cognitive damage to children, harm the kidneys and cause heart disease, among other issues. Lead, mercury, cadmium and arsenic are all carcinogens.

Rubin first learned that lead was added to toothpaste about 12 years ago while working with families that had children with high levels of the metal in their blood. The common denominator among them was a brand of toothpaste, Earthpaste, that contained lead.

Last year she detected high levels in some toothpaste using an XRF lead detection tool. The levels were high enough to raise concern, and she crowdfunded with readers to send popular brands to an independent laboratory for testing.

Among those found to contain the toxins were Crest, Sensodyne, Tom’s of Maine, Dr Bronner’s, Davids, Dr Jen and others.

So far, none of the companies Lead Safe Mama checked have said they will work to get lead out of their product, Rubin said. Several sent her cease-and-desist letters, which she said she ignored, but also posted on her blog.

Some companies have defended themselves, often claiming that lead is found in trace levels throughout the environment and is impossible to avoid. Others have said the levels Rubin found are not concerning.

The federal Baby Food Safety Act of 2024, which is stalled in Congress, called for lead limits in kids’ food or personal care products like toothpaste of five parts per billion (ppb). California’s limit on lead in baby food is two ppb, but it does not include toothpaste.

Most toothpastes exceeded those thresholds.

The FDA’s current lead limit for children is 10,000 ppb, and 20,000 ppb for adults. None exceeded the FDA limits.

The state of Washington recently enacted a law with 1,000 ppb limits – several exceeded that and have been reported, Rubin said, but companies have time to get in compliance with the new rules.

The FDA did not immediately respond to a request for comment, nor did Crest’s parent company, Procter & Gamble.

Rubin said the contamination seems to lie in some ingredients added to toothpaste, including hydroxyapatite, calcium carbonate and bentonite clay. Hydroxyapatite is extracted from cow bone and added because it allegedly helps teeth absorb calcium, though Rubin said she doubts it does. Calcium carbonate is added to help remove stains from teeth. Bentonite clay is a cleaning agent.

Those with the highest levels all had bentonite clay. Meanwhile, Rubin’s testing of hydroxyapatite and calcium carbonate as individual ingredients showed concerning levels of lead and other metals, suggesting those are the source.

Several children’s toothpastes, like Dr Brown’s Baby Toothpaste, did not test positive for any metals and did not contain the ingredients in question.

A giant planet 124 light years from Earth has yielded the strongest evidence yet that extraterrestrial life may be thriving beyond our solar system, astronomers claim.

Observations by the James Webb space telescope of a planet called K2-18 b appear to reveal the chemical fingerprints of two compounds that, on Earth, are only known to be produced by life.

Detection of the chemicals, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) would not amount to proof of alien biological activity, but could bring the answer to the question of whether we are alone in the universe much closer.

“This is the strongest evidence to date for a biological activity beyond the solar system,” said Prof Nikku Madhusudhan, an astrophysicist at the University of Cambridge who led the observations. “We are very cautious. We have to question ourselves both on whether the signal is real and what it means.”

He added: “Decades from now, we may look back at this point in time and recognise it was when the living universe came within reach. This could be the tipping point, where suddenly the fundamental question of whether we’re alone in the universe is one we’re capable of answering.”

Others are more sceptical, with questions remaining about whether the overall conditions on K2-18 b, are favourable to life and whether DMS and DMDS, which are largely produced by marine phytoplankton on Earth, can be reliably regarded as biosignatures.

K2-18 b, which sits in the Leo constellation, is nearly nine times as massive as the Earth and 2.6 times as large and orbits in the habitable zone of its star, a cool red dwarf less than half the size of the sun. When the Hubble space telescope appeared to spot water vapour in its atmosphere in 2019, scientists declared it “the most habitable known world” beyond the solar system.

The supposed water signal was shown to be methane in follow-up observations by Madhusudhan’s team in 2023. But, they argued, K2-18 b’s profile was consistent with a habitable world, covered in a vast, deep ocean – a view that remains contentious. More provocatively, the Cambridge team reported a tentative hint of DMS.

Planets beyond our solar system are too distant to photograph or reach with robotic spacecraft. But scientists can estimate their size, density and temperature and probe their chemical makeup by tracking the exoplanet as it passes across the face of its host star and measuring starlight that has been filtered through its atmosphere. In the latest observations, wavelengths that are absorbed by DMS and DMDS, were seen to suddenly drop off as K2-18 b wandered in front of the red dwarf.

“The signal came through strong and clear,” said Madhusudhan. “If we can detect these molecules on habitable planets, this is the first time we’ve been able to do that as a species … it’s mind-boggling that this is possible.”

The findings, published in The Astrophysical Journal Letters, suggest concentrations of DMS, DMDS or both (their signatures overlap) thousands of times stronger than the levels on Earth. The results are reported with a “three-sigma” level of statistical significance (a 0.3% probability that they occurred by chance) although this falls short of the gold standard for discoveries in physics.

“There may be processes that we don’t know about that are producing these molecules,” Madhusudhan said. “But I don’t think there is any known process that can explain this without biology.”

A challenge in identifying potential other processes is that the conditions on K2-18 b remain disputed. While the Cambridge team favour an ocean scenario, others say the data is suggestive of a gas planet or one with oceans made of magma, not water.

There is a question of whether DMS could have been brought to the planet by comets – this would require an intensity of bombardment that seems improbable – or produced in hydrothermal vents, volcanoes or lightning storms through exotic chemical processes.

“Life is one of the options, but it’s one among many,” said Dr Nora Hänni, a chemist at the Physics Institute of the University of Berne, whose research revealed that DMS was present on an icy, lifeless comet. “We would have to strictly rule out all the other options before claiming life.”

Others say that measuring planetary atmospheres may never yield a smoking gun for life. “It’s under-appreciated in the field, but technosignatures, such as an intercepted message from an advanced civilisation, could be better smoking guns, despite the unlikelihood of finding such a signal,” said Dr Caroline Morley, an astrophysicist at the University of Texas, Austin, adding that the findings were, nonetheless, an important advance.

Dr Jo Barstow, a planetary scientist at the Open University, also viewed the detection as significant, but said: “My scepticism dial for any claim relating to evidence of life is permanently turned up to 11, not because I don’t think that other life is out there, but because I feel that for such a profound and significant discovery the burden of proof must be very, very high. I don’t think this latest work crosses that threshold.”

At 120 light years away, there is no prospect of resolving the debate through closeup observations, but Madhusudhan notes that this has not been a barrier to the discovery of black holes or other cosmic phenomena.

“In astronomy, the question is never about going there,” he said. “We’re trying to establish if the laws of biology are universal in nature. I don’t see it as: ‘We have to go and swim in the water to catch the fish.’”

France has a moral duty to reimburse Haiti billions of dollars worth of “ransom” payments that could help the struggling Caribbean country out of its current crisis, say campaigners.

The renewed call for reparations comes on the bicentenary of an agreement to pay 150m francs to France in 1825 to compensate slave-owning colonists after the Haitian Revolution.

Though the figure was later reduced to 90m, Fritz Deshommes, president of the Haitian National Committee on Restitution and Reparations (HNCRR), estimates the converted value of the payment today could be between $38bn and $135bn, depending on how the sum is calculated and whether it reflects lost customs revenue and economic stagnation.

Once France’s most important colony in the Caribbean, Haiti received hundreds of thousands of Africans who had been kidnapped, forcibly transported across the Atlantic and sold into slavery.

After a bloody struggle between self-liberated slaves and French, Spanish and British forces, it became the first Caribbean nation to gain its independence from colonial rule in 1804.

But, under threat of military action, France later demanded what HNCRR member Jean Mozart Feron described as an unjust and exorbitant ransom, supposedly to provide compensation for former enslavers.

The enormous payments, Feron said, crippled the fledgling nation. “This ransom plunged Haiti into a spiral of economic dependency from which it has never fully recovered and … strangled the young nation, stifling its development and diverting precious resources that could have been invested in education and infrastructure,” he said.

The debt not only created deep structural poverty, social inequality and weak institutions, but also affected “the way Haiti is perceived and treated on the international stage without due consideration for this history of economic exploitation”, he said.

Monique Clesca, spokesperson for the Kolektif Ayisyen Afwodesandan, a civil society organisation that has been campaigning for reparations for Haiti, said the “monstrous debt” created by the ransom prevented the country from “moving forward at the rhythm that we should have been moving forward”.

“Politically this meant that we almost became a neocolony, totally indebted to France, not only in terms of economics, but symbolically and politically, we were tied. So there are serious repercussions and consequences to this continuous debt that you can’t undo,” she said.

The campaigners are calling for France to repay the ransom and offer restitution for the harm caused by slavery and colonisation.

The HNCRR is working in alignment with the Caribbean Community (Caricom), which has a 10-point plan for reparatory justice.

Speaking at the opening of the UN’s Permanent Forum on People of African Descent on Monday, Caricom secretary-general, Dr Carla Barnett, joined the calls for reparations for Haiti.

“The negative economic and social effects of this historical injustice are painfully clear, with arguable links to the situation in Haiti today. This anniversary presents an opportunity to bring global attention and a deeper understanding of the situation in Haiti and serves as a call to action to address the ongoing security, humanitarian and governance crises in the country,” she said.

Appealing for global support for Haiti’s reparations claim, Heron said: “Haitian citizens do not hold French people responsible for the decision made in 1825 by the French state. However, we believe that the French people have a moral responsibility and a duty to stand in solidarity with the Haitian people in this initiative.”

HNCRR, he said, is of the view that France and Haiti could reach an agreement about the “types of expertise and technical assistance valued within the framework of restitution”. But Haiti, he added, must ultimately decide how to use the reparations.

Haiti has been gripped by crisis since the 2021 assassination of president Jovenel Moïse, and a subsequent gang insurgency which forced Ariel Henry, who led the country as an unelected prime minister after Moïse’s death, out of office in March 2024. Since then, support from the international community has failed to restore stable, democratic governance and curb the spiralling violence, which has killed thousands and displaced tens of thousands.

Feron dismissed arguments that the current crisis could prevent the country from effectively managing any reparation payments, arguing that the state of the country is a consequence of its history.

He added: “Our committee intends to work closely with the civil society to clearly advise the Haitian state on how this money should be used or could be used and how it should be managed with total transparency in a responsible manner.”

France has a moral duty to reimburse Haiti billions of dollars worth of “ransom” payments that could help the struggling Caribbean country out of its current crisis, say campaigners.

The renewed call for reparations comes on the bicentenary of an agreement to pay 150m francs to France in 1825 to compensate slave-owning colonists after the Haitian Revolution.

Though the figure was later reduced to 90m, Fritz Deshommes, president of the Haitian National Committee on Restitution and Reparations (HNCRR), estimates the converted value of the payment today could be between $38bn and $135bn, depending on how the sum is calculated and whether it reflects lost customs revenue and economic stagnation.

Once France’s most important colony in the Caribbean, Haiti received hundreds of thousands of Africans who had been kidnapped, forcibly transported across the Atlantic and sold into slavery.

After a bloody struggle between self-liberated slaves and French, Spanish and British forces, it became the first Caribbean nation to gain its independence from colonial rule in 1804.

But, under threat of military action, France later demanded what HNCRR member Jean Mozart Feron described as an unjust and exorbitant ransom, supposedly to provide compensation for former enslavers.

The enormous payments, Feron said, crippled the fledgling nation. “This ransom plunged Haiti into a spiral of economic dependency from which it has never fully recovered and … strangled the young nation, stifling its development and diverting precious resources that could have been invested in education and infrastructure,” he said.

The debt not only created deep structural poverty, social inequality and weak institutions, but also affected “the way Haiti is perceived and treated on the international stage without due consideration for this history of economic exploitation”, he said.

Monique Clesca, spokesperson for the Kolektif Ayisyen Afwodesandan, a civil society organisation that has been campaigning for reparations for Haiti, said the “monstrous debt” created by the ransom prevented the country from “moving forward at the rhythm that we should have been moving forward”.

“Politically this meant that we almost became a neocolony, totally indebted to France, not only in terms of economics, but symbolically and politically, we were tied. So there are serious repercussions and consequences to this continuous debt that you can’t undo,” she said.

The campaigners are calling for France to repay the ransom and offer restitution for the harm caused by slavery and colonisation.

The HNCRR is working in alignment with the Caribbean Community (Caricom), which has a 10-point plan for reparatory justice.

Speaking at the opening of the UN’s Permanent Forum on People of African Descent on Monday, Caricom secretary-general, Dr Carla Barnett, joined the calls for reparations for Haiti.

“The negative economic and social effects of this historical injustice are painfully clear, with arguable links to the situation in Haiti today. This anniversary presents an opportunity to bring global attention and a deeper understanding of the situation in Haiti and serves as a call to action to address the ongoing security, humanitarian and governance crises in the country,” she said.

Appealing for global support for Haiti’s reparations claim, Heron said: “Haitian citizens do not hold French people responsible for the decision made in 1825 by the French state. However, we believe that the French people have a moral responsibility and a duty to stand in solidarity with the Haitian people in this initiative.”

HNCRR, he said, is of the view that France and Haiti could reach an agreement about the “types of expertise and technical assistance valued within the framework of restitution”. But Haiti, he added, must ultimately decide how to use the reparations.

Haiti has been gripped by crisis since the 2021 assassination of president Jovenel Moïse, and a subsequent gang insurgency which forced Ariel Henry, who led the country as an unelected prime minister after Moïse’s death, out of office in March 2024. Since then, support from the international community has failed to restore stable, democratic governance and curb the spiralling violence, which has killed thousands and displaced tens of thousands.

Feron dismissed arguments that the current crisis could prevent the country from effectively managing any reparation payments, arguing that the state of the country is a consequence of its history.

He added: “Our committee intends to work closely with the civil society to clearly advise the Haitian state on how this money should be used or could be used and how it should be managed with total transparency in a responsible manner.”

Two of China’s largest fast fashion retailers, Temu and Shein, have warned US customers that they will face price increases from next week, as Donald Trump’s hefty tariffs on Chinese imports come into force.

Both companies will be hit by new import levies, which will mean taxes of up to 145% being applied to Chinese goods. They will also suffer from Trump’s cancellation of the “de minimis” exemption, under which shipments worth less than $800 (£600) could be imported duty-free.

That exemption was crucial in helping the low-cost retailers make inroads into the US market, where they were able to send low-cost online purchases with few expenses. It will be removed as of 2 May.

“Due to recent changes in global trade rules and tariffs, our operating expenses have gone up,” Shein’s customer notice said.

“To keep offering the products you love without compromising on quality, we will be making price adjustments starting 25 April 2025. We’re doing everything we can to keep prices low and minimise the impact on you,” the company said.

Under Trump’s original plans, previously exempt packages were due to be hit with a tariff rate of 30% or $25 an item, rising to $50 an item by 1 June. However, after China responded with retaliatory tariffs last week, Trump hit back by tripling the rates for previously exempt packages to 90% or $75 an item, rising to $150 on 1 June.

Some experts say it is unlikely to deter all customers, given that items from Temu and Shein could still end up cheaper than some rival retailers.

Meanwhile, the imposition of US tariffs has prompted the retailers to cut spending on US social media advertising, which has also bolstered their profile among young and thrifty shoppers.

Temu’s daily average US ad spend on Facebook, Instagram, TikTok, Snap, X and YouTube declined by a collective average of 31% in the two weeks from 31 March to 13 April compared with the previous 30 days, according to the digital marketing company Sensor Tower.

Meanwhile, Shein’s daily average US ad spend on Facebook, Instagram, TikTok, YouTube and Pinterest fell a collective average of 19% over the same period. Mark Ballard, the director of digital marketing research at Tinuiti, said Temu had sharply reduced ads on Google Shopping since 12 April.

Meta declined to comment, while Google, Shein and Temu were not immediately available for comment.

Reuters contributed to the report

Updated guidance for public bodies after the UK supreme court’s ruling that a woman is defined in law by biological sex is expected to be issued by the summer, the head of the equalities regulator said on Thursday.

Lady Kishwer Falkner, the chair of the Equality and Human Rights Commission, described the ruling as “enormously consequential”, telling BBC Radio 4’s Today programme: “We are going to have a new statutory code of practice, statutory meaning it will be the law of the land, it will be interpreted by courts as the law of the land. We’re hoping we’re going to have that by the summer.”

She said it would give “clarity” that trans women could not participate in women’s sports or use women-only toilets or changing rooms, and the NHS must update its guidance on single-sex wards based on biological sex.

Asked if the supreme court ruling was “a victory for common sense”, she said: “Only if you recognise that trans people exist, they have rights and their rights must be respected. Then it becomes a victory for common sense.

“It’s not a victory for an increase in unpleasant actions against trans people. We will not tolerate that. We stand here to defend trans people as much as we do anyone else. So I want to make that very clear.”

She emphasised that trans people still had clear protection under legislation. “They are covered through gender reassignment … and they’re also covered by sex discrimination.”

Asked to give an example, she said: “We’ll have to flesh this out in the reasoning, but I think if you were to have an equal pay claim, then depending on which aspect of it that it was, you could use sex discrimination legislation. If a trans person was fired, lost their employment because they happen to be trans, that would be unlawful, still absolutely unlawful, and we stand ready to support those people and those claims.”

On the risk that trans people will no longer be able to use facilities designed for either male or female, she added that trans rights organisations should push for more neutral third spaces. “But I think the law is quite clear that if a service provider says we’re offering a women’s toilet, that trans people should not be using that single-sex facility.”

Falkner added that the EHRC would pursue the NHS to change its existing guidance on the treatment of trans patients, which currently say that trans people should be accommodated in single-sex accommodation according to their gender identity, rather than their assigned sex at birth.

“They [the NHS] have to change it. They now have clarity,” she said. “We will be having conversations with them to update that guidance.”

The “efficacy” of the gender recognition certificate, a UK legal document that recognises an individual’s gender identity, allowing them to legally change their sex, would be re-examined, she believed. The government is considering introducing digital IDs, “and if digital IDs come in, then what documentation will provide the identity of that person? So it’s going to be a space that we’ll have to watch very carefully as we go on.”

Venice’s entrance fee will resume from Friday, with the main novelty this year being that last-minute day-trippers will pay double.

Last year, as part of an experiment aimed at dissuading day visitors during busy periods, Venice became the first major tourist city in the world to charge people to enter.

Although the initiative made little impact on visitor numbers, it did rake in €2.4m for the lagoon city’s coffers, much more than expected, and Venice authorities still believe it will eventually contribute to helping the Unesco world heritage city tackle overtourism.

This year’s levy, which is bookable online, remains €5, but will double if bought within three days before arrival in the city. Furthermore, it has been expanded to apply on 54 dates, mostly weekends, between 18 April and 27 July, almost double the number of days compared with last year. The measure applies between 8.30am and 4pm local time.

Visitors are provided with a QR code which they will need to present to stewards hired to patrol the city’s main entrance points, for example Venezia Santa Lucia train station.

Anyone who books an overnight stay in Venice is exempt from paying the fee, as are tourists from the wider Veneto region, which is where most day-trippers come from, as well as children under the age of 14. But even if a visitor has booked a hotel room they are still obliged to register their presence on the website.

Last year set a new record for visitors to Venice and its wider area, with more than 3.9 million staying overnight in the city’s historic centre. However, roughly 30 million people visit each year, the majority coming just for the day.

More than 35,000 day-trippers have already booked a ticket, according to the local news website Venezia Today.

Simone Venturini, Venice’s councillor for tourism, said that while there was “no magic wand” solution to a problem affecting many European tourist cities, the access fee scheme “represents a tangible and innovative tool” in terms of data analysis and managing visitor flows.

“It will be a long journey, but from now on the city will be able to rely on objective data rather than mere estimates to understand the phenomenon of overtourism,” he said. “Our goal is to encourage quality tourism – overnight stays – that respects the city and seeks to engage with it on a deeper level, embracing its unique character and rhythm.”

Another goal was to “strike a better balance between the rights of those who live in Venice and those who wish to visit it”, he added.

While the fee was mostly embraced by tourists last year, it was bitterly contested by Venice’s residents. Many of them believe the only real way to achieve more sustainable tourism would be to target the people who stay overnight by clamping down on short-term holiday lets and improving services for the year-round population, which in 2022 fell below 50,000 for the first time.

Giovanni Andrea Martini, a Venice councillor for the opposition, is among the fee’s most prominent critics.

“It has made absolutely no difference,” he said. “The numbers have actually been increasing. In recent days, we have been overwhelmed.”

Although there have been no new protests against the fee, residents have objected to attempts to encourage tourists to visit lesser-known areas of Venice’s main island.

“It is a measure aimed at reducing tourist pressure but naturally it has provoked anger among people living in these areas as it will disrupt their peace,” said Martini. “It is becoming even more tragic for those who live here.”

Plantains, cassava and fermented banana drink should be added to global healthy eating guidelines alongside the olive oil, tomatoes and red wine of the Mediterranean diet, say researchers who found the traditional diet of people living in Tanzania’s Kilimanjaro region had a positive impact on the body’s immune system.

Traditional foods enjoyed in rural villages also had a positive impact on markers of inflammation, the researchers found in a study published this month in the journal Nature Medicine.

Dr Quirijn de Mast, one of the paper’s authors, said they were now in a race against time to record and study the potential benefits of African heritage diets before they disappear as people move to cities and adopt western-style eating habits.

“Time is ticking because you see that these heritage diets are being replaced more and more by western diets,” he said. “We will lose so much interesting information [from which] we can learn – and not only for Africa.”

In previous research, the team had established that people following the traditional way of life in rural areas had a different immune-system profile to urban dwellers, with more anti-inflammatory proteins. Chronic inflammation is a key driver of many non-communicable diseases (NCDs), including rheumatoid arthritis and Alzheimer’s disease.

The new study set out to establish whether diet played a role. For a fortnight, 77 young men in their 20s and 30s were switched from heritage to western-style diets, or the reverse – with blood samples taken at the start and end, and again four weeks later.

Meals on the heritage diet menu included green plantain mixed with kidney beans, boiled chicken served with green vegetables and brown rice and beans. On the western-style menu, they included pizza, fried chicken and french fries and spaghetti served with beef stew.

Those newly adopting a western-style diet saw inflammatory markers in their blood increase and tests suggested their immune systems did not respond as well to infections. They also gained weight. By contrast, switching from a western diet to a heritage diet had a largely anti-inflammatory effect, and blood markers linked to metabolic problems fell.

In a third arm of the trial, participants following a western-style diet were asked to drink the local fermented banana beverage, known as mbege, for one week. That group also saw improvements in markers of inflammation.

For Dr Godfrey Temba, the first author of the paper and a lecturer at KCMC University in Moshi, Tanzania, the findings were not a surprise. “When we are in most of the villages, talking to elderly people [of] 80 or 90 years, they are very healthy. They don’t have any health complications [and] they tell you about consuming this type of diet and this beverage since they were 25.”

However, the diet and its benefits have not been explored and documented – unlike the traditional diets of the Mediterranean and Nordic countries, which are promoted by the World Health Organization for their beneficial effects.

Temba said: “We think this is the right time … so that [African heritage diets] can be also included in the global guidelines of diets, because they really have a health benefit – but because it’s not studied extensively, it’s not easy to convince [people] that they are healthy, because you don’t have enough data.”

The diet’s components, such as flavonoids and other polyphenols, and its impact on the gut microbiome were likely to play a part in the observed effects, De Mast said.

The study was conducted only in men for logistical reasons, but the researchers said they would expect similar findings in women, and for benefits to be maintained over time if people continued the diets.

Many African countries are facing rising rates of NCDs such as diabetes, obesity and heart disease.

De Mast, who holds positions at KCMC University and Radboud University Medical Center in the Netherlands, said research priorities in Africa had historically been determined by countries in the global north with a focus on infectious diseases such as malaria, tuberculosis and HIV. “Research on [things like] immunology has been neglected. I hope it will change now, with the rapid rise in NCDs, because that will be a major challenge for health systems across Africa.”

Nutritional guidelines also tended to “translate what we know from the north to Africa”, he said. “I think you should have, really, region-specific recommendations based on scientific data.”

The team is now testing what impact adopting a heritage diet can have on Tanzanians living with obesity, including whether it can boost their response to vaccines, and plan to compare different regional heritage diets.

“There’s so much diversity in dietary patterns across Africa – or [even just] in Tanzania,” said De Mast. “Godfrey is in Kilimanjaro region, but 30km down the road there is the Maasai tribe and their diet is entirely different. It’s mainly animal protein based – still, traditionally, cardiovascular disease was almost absent.

“So I think this is just the beginning of research looking at these heritage diets.”