Butterflies Populations are falling in the United States, a new study has found.

 

 

By Catrin Einhorn and Harry Stevens

 

 

It’s hard to count insects.

Even as scientists have found that many populations are in decline, they’ve struggled to understand the scale of what’s happening. Now, a groundbreaking new study offers the most comprehensive answers to date about the status of butterflies in the contiguous United States.

In 20 years, the fleeting time it takes for a human baby to grow into a young adult, the country has lost 22 percent of its butterflies, researchers found. 

 In New York, N.Y., 128 species included in the study are known to occur.

 

“The loss that we’re seeing over such a short time is really alarming,” said Elise Zipkin, a quantitative ecologist at Michigan State University and one of the authors of the study, which was published on Thursday in the journal Science. “Unless we change things, we’re in for trouble.”

Little-understood and vastly underappreciated, insects play an outsize role in supporting life on earth. They pollinate plants. They break down dead matter, nourishing the soil. They feed birds and myriad other creatures in the food web.

“Nature collapses without them,” said David Wagner, an entomologist at the University of Connecticut.

Dr. Wagner, who was not involved with the new research, called it a “much-needed, herculean assessment.” He praised the study’s rigor and noted that the declines in butterflies, amounting to 1.3 percent per year, were in line with other recent efforts to analyze global trends in terrestrial insect populations.

Still, researchers didn’t have enough data to include some of the most imperiled butterfly species, which probably experienced some of the steepest declines. And the data was quite likely biased toward places where butterflies tend to show up. “Unfortunately for nature,” Dr. Wagner said, the findings are “undoubtedly a conservative assessment.”

The analysis was based on 12.6 million individual butterflies counted in almost 77,000 surveys across 35 monitoring programs from 2000 to 2020. 

 

That data came largely from volunteers who, working with various programs, showed up in a certain location on certain days over the years to document every butterfly they saw.

The researchers — some who specialize in math, others who are experts in butterfly species and behavior — took that raw data and harmonized it, creating a model that estimated the changes in abundance.

Of the 342 species for which they were able to draw conclusions, 33 percent showed statistically significant declines and less than 3 percent displayed statistically significant increases. Thirteen times as many species decreased as increased.

The American lady, an orange-and-black butterfly that ranges from coast to coast, was down 58 percent.

The Hermes copper, a rare butterfly found in San Diego County, plummeted by 99.9 percent.

Even the cabbage white, originally from Europe and so commonly found munching on vegetables as a caterpillar that it’s considered an invasive pest, dropped by half.

“That shocked me,” said Nick Haddad, an insect ecologist at Michigan State and an author on the study. “If even the cabbage white is declining, then, oh my God.” 

 

The research could not shed much light on how monarch butterflies are doing, the authors said. Monarchs, which the U.S. Fish and Wildlife Service in December recommended for federal protection, have shown staggering declines in their overwintering sites in Mexico and California. But separate new data offered a dose of good news on that front: After hitting an almost record low last year, overwintering monarchs in Mexico rebounded significantly in this year’s count, made public by the Mexican government and the World Wildlife Fund on Thursday.

Scientists attributed much of the increase to an easing of drought conditions along the migration route of eastern monarchs, which travel between the United States, Canada and Mexico. But monarchs west of the Rocky Mountains, which overwinter in California, were at near record lows in this year’s count.

Why are butterflies crashing? Experts blame a combination of factors: habitat loss as land is converted for agriculture or development, climate change and pesticide use. What’s less clear is the extent to which each factor is driving the declines.

The study doesn’t try to answer that question, but it points to other findings, from the Midwest and California, that insecticides have played a particularly lethal role. A class called neonicotinoids, which Europe largely banned in 2018, was found to be especially deadly.

Members of the public are often called upon to plant native milkweed to help monarch caterpillars, but a study in the Central Valley of California found that every single collected sample was contaminated with pesticides. That was true even when landowners said they did not use pesticides, suggesting that the chemicals had drifted or had been applied to plants before purchase.

The new findings do show potential fingerprints from climate change. As the world warms, North American species are moving northward in search of more hospitable conditions. When researchers compared the same species in neighboring regions, they found that the northern populations were faring better than southern ones in three-quarters of cases. Moreover, two-thirds of the species that showed overall increases in the United States have ranges with more area in Mexico than in the United States and Canada, suggesting that perhaps they are growing in the northern parts of their range. Without data from Mexico, researchers can’t tell what’s happening there.

The researchers emphasized that solutions are at hand. Some, like tackling climate change and regulating pesticides, need to happen at the policy level. But in the meantime, they encouraged people to create habitat refuges for butterflies and other insects by planting native flowers, shrubs and trees. One butterfly, the Gulf fritillary, appears to have increased its range as homeowners planted passionvine, which its caterpillars eat.

And remember those caterpillars, said Collin Edwards, an ecological modeler for the Washington Department of Fish and Wildlife and the lead author of the study.

“If you’re spraying something on your plants to keep things from eating them, caterpillars are eating plants,” he said. “Those are butterflies-to-be.”

Global sea ice hit ‘all-time minimum’ in February, scientists say. Scientists called the news ‘particularly worrying’ because ice reflects sunlight and cools the planet

February was the lowest monthly level for sea ice in the Arctic, and the fourth-lowest in the Antarctic. Photograph: Bernhard Staehli/Shutterstock
 

Ajit Niranjan Europe environment correspondent

 

 

Global sea ice fell to a record low in February, scientists have said, a symptom of an atmosphere fouled by planet-heating pollutants.

The combined area of ice around the north and south poles hit a new daily minimum in early February and stayed below the previous record for the rest of the month, the EU’s Copernicus Climate Change Service (C3S) said on Thursday.

“One of the consequences of a warmer world is melting sea ice,” said the C3S deputy director, Samantha Burgess. “The record or near-record low sea ice cover at both poles has pushed global sea ice cover to an all-time minimum.”

The agency found the area of sea ice hit its lowest monthly level for February in the Arctic, at 8% below average, and its fourth-lowest monthly level for February in the Antarctic, at 26% below average. Its satellite observations stretch back to the late 1970s and its historical observations to the middle of the 20th century.

Scientists had already observed an extreme heat anomaly in the north pole at the start of February, which caused temperatures to soar more than 20C above average and cross the threshold for ice to melt. They described the latest broken record as “particularly worrying” because ice reflects sunlight and cools the planet.

“The lack of sea ice means darker ocean surfaces and the ability of the Earth to absorb more sunlight, which accelerates the warming,” said Mika Rantanen, a climate scientist at the Finnish Meteorological Institute.

The strong winter warming event in the Arctic in early February had prevented sea ice from growing normally, he added. “I believe that this meteorological event, combined with the long-term decline of sea ice due to anthropogenic climate change, was the primary cause of the lowest Arctic sea ice extent on record.”

Global sea ice extent varies throughout the year but typically reaches its annual minimum in February, when it is summer in the southern hemisphere

C3S said February 2025 was the third hottest February it had seen. Global temperatures were 1.59C hotter than preindustrial levels, making it the 19th month in the past 20 that was more than 1.5C above preindustrial levels.

Earth observation programmes such as C3S rely on the reanalysis of billions of measurements from satellites, ships, aircraft and weather stations to create snapshots of the state of the climate. The agency cautioned that the margins above 1.5C were small in several months, and could differ slightly in other datasets.

 

The broken sea ice record comes after last year was confirmed as the hottest year on record and a Guardian analysis of C3S data revealed that two-thirds of the world’s surface was seared by record-breaking monthly heat in 2024. The El Niño weather pattern in the first half of the year added to the background heating effect of fossil fuel pollution, which traps sunlight.

El Niño has since subsided and morphed into a weak form of its cooler counterpart, La Niña. The World Meteorological Organization said on Thursday they expected the La Niña that emerged in December to be short-lived.

Richard Allan, a climate scientist at the University of Reading, said the long-term prognosis for Arctic sea ice was grim.

“The region continues to rapidly heat up, and can only be saved with rapid and massive cuts to greenhouse gas emissions,” he said. “That will also limit the growing severity of weather extremes and long-term sea level rise across the world.”

 

Why Vermont farmers, USA, are using pasteurised urine on their crops

 

 In Vermont, pasteurised urine is sprayed on local farmland to fertilise crops (Credit: Rich Earth Institute)

 Becca Warner

 

Urine was used as fertiliser in ancient Rome and China. Now farmers in Vermont are bringing this practice back to boost harvests and grow crops in a more sustainable way.

When Betsy Williams goes to the loo, she likes to know her pee won't go to waste. For the last 12 years, she and her neighbours in rural Vermont, US, have diligently collected their urine and donated it to farmers for use as fertiliser for their crops.

"We're consuming all of these things that have nutrients in them, and then a lot of the nutrients that are passing through us can then get recycled back into helping create food for us and for animals. So to me, it's logical," Williams says.

Williams takes part in the Urine Nutrient Reclamation Program (UNRP), a programme run by the Rich Earth Institute (REI), a non-profit based in Vermont. She and 250 of her neighbours in Windham County donate a total of 12,000 gallons (45,400 litres) of urine to the programme each year to be recycled – or "peecycled". 

Windham County's pee-donations are collected by a lorry and driven to a large tank where the urine is pasteurised by heating it to 80C (176F) for 90 seconds. It is then stored in a pasteurised tank, ready to be sprayed on local farmland when the time is right to fertilise crops.

 

Records suggest that urine was used to help grow crops back in ancient China and ancient Rome. Today, scientists are finding that it can more than double the yield of crops like kale and spinach compared to no fertiliser, and improve yields even in low fertility soils.

Urine's power as a fertiliser is due to the nitrogen and phosphorus that it contains – the same nutrients that are added to the synthetic fertilisers used on many conventional farms. But these synthetic fertilisers come at an environmental cost. Nitrogen is produced using the fossil fuel-intensive Haber-Bosch process, and the mining of phosphorus creates harmful amounts of toxic waste. Urine, meanwhile, is freely available – as Williams puts it, "everybody pees. [It's an] untapped resource".

Urine's power as a fertiliser is due to the nitrogen and phosphorus that it contains (Credit: Rich Earth Institute)

Nancy Love, a professor of civil and environmental engineering at the University of Michigan who has collaborated with the team at REI over the last decade, has found that using urine instead of standard synthetic fertiliser reduces greenhouse gas emissions, and requires around half the amount of water. Indeed, since 2012, UNRP estimates that it has conserved over 2.7 million gallons (10.2 million litres) of water through preventing toilet flushes.

"I've always been a systems thinker, and our [water] system has inefficiencies in it," Love says. "What we do today is dilute the hell out of our urine, we put it in a pipe, we send it to a treatment plant, and then we pump a bunch more energy into it, just to send it back into the environment in a reactive form."

 

In the case of urine's nutrients, its typical destination is waterways. The nitrogen and phosphorus in urine are not fully removed from wastewater when it is treated. When these nutrients find their way into rivers and lakes, they are taken up by algae. The result can be algal blooms that choke up waterways, unbalancing the ecosystem and killing other species that live there.

"Our bodies create a lot of nutrients, and right now those nutrients are not only wasted, but they’re actually causing a lot of problems and harm downstream," says Jamina Shupack, REI's executive director.

These nutrients are food for algae – but also for crops. "Wherever you put nitrogen, it's going to help plants grow. So if it's in the water, it's helping the algae grow. But if it's on the land, it's going to help plants grow,” Shupack explains. Because of this, diverting nutrient-rich urine away from waterways and onto the land can prevent harmful algal blooms while helping farmers grow food.

 Everybody pees. It's an untapped resource – Betsy Williams

 Importantly, the REI team and the farmers they work with take steps to minimise how much of the urine runs off the land and into waterways. Application is carefully timed, so that it happens when the plant is most able to take up the nutrients – typically during the plant's more active growth stage, when it's bigger than a seedling but not yet fruiting. The soil moisture is also measured, to make sure the liquid urine will be absorbed. Despite these efforts, "that doesn't mean that there isn't going to be runoff", Shupack says.

 

Even so, she adds, peecycling reduces the overall amount of nutrients entering waterways because it ensures that runoff from the land is the only way excess nutrients enter rivers and lakes. In the current system, synthetic fertilisers run off into waterways, as well as urine entering rivers directly via wastewater.

The UNRP in Vermont is pioneering peecycling in the US, but projects in other countries are also underway. In Paris, volunteers are collecting urine to help save the River Seine and fertilise wheat for baguettes and biscuits. Swedish entrepreneurs saw the harm caused by algal blooms around the island of Gotland and came up with a product that collects urine and turns it into fertiliser. Peecycling pilots have also run in South Africa, Nepal and Niger Republic.

 

Research shows that urine can more than double the yield of certain crops (Credit: Rich Earth Institute)

But expanding this work comes with challenges. Shupack says that in Vermont, farmers' demand for urine outstrips supply – but scaling up collection is tricky. Regulation can create a barrier, she says. "A lot of times you go to a regulator and they say: 'We don't have a form for urine – the only place I know where to put urine is with biosolids, or within wastewater treatment.' So it's not really categorised in a way that would make sense to do what we're doing," she says.

To overcome this, Shupack says that REI have got to grips with the detailed language of regulations so they could spot possible paths and partnered with organisations with existing permits – such as septic haulers – to tackle the different parts of the process, and the permits needed, in a piecemeal way.

 

Eamon Twohig, programme manager at Vermont's Department of Environmental Conservation (VTDEC), tells the BBC that when REI initially approached them "it was clear there was no 'regulatory box' for urine treatment/recycling… REI has certainly blazed a trail here in Vermont, and I think we've managed to find a workable, regulatory pathway."

REI has a good relationship with regulators in Vermont, Shupack says, and has all the permits needed to operate – including one for innovative on-site wastewater management, and a waste-hauling permit for transporting urine. Now the organisation is working with partners in Massachusetts and Michigan to move regulation on. "We're really trying to push that forward. But it's not always easy to get new environmental regulations updated," Shupack says. One of the biggest challenges, she adds, is that there is no legal distinction between human waste that has been separated at source, and combined wastewater flows that often come with greater safety concerns. 

There are other limitations too. Urine is heavy and cumbersome to transport, and the lorries collecting and moving it create emissions. Currently the urine in Vermont is transported locally, no more than around 10 miles (16km). But expanding peecycling programmes could involve moving urine across bigger distances, so REI's spinoff company has developed a freeze concentration system that concentrates urine by six times, and is currently being used at the University of Michigan.

 

Plumbing, too, is a particular challenge. Love says that urine separation systems don't rely on flushing in the same way standard toilets do – which is great for reducing water use, but is problematic for the plumbing. When water doesn't flow through the system as usual, there is a risk of diseases such as Legionnaires.

"There are solutions," Love says, "like looped systems in a building. But what it means is the entire plumbing process in a building is different." This is something Love and her colleagues and partners are working on, so that new buildings in the US can have urine separation systems installed from the start. "If we want any hope of sustainable water systems by the end of this century, we have to start getting the early adopters to look at these innovative solutions now," she says.

The Rich Earth Institute collects a total of 12,000 gallons (45,400 litres) of urine each year (Credit: Rich Earth Institute)

These new systems will have the important goal of making urine donation effortless. Williams began her peecycling efforts using large laundry detergent bottles that travelled in the boot of her car to a central collection tank once a month. Once she was in the habit of collecting urine, Williams didn't like to let it go to waste. "I didn't even like to go anywhere where I might have to pee and not have a jug with me. It kind of became part of my routine, sort of like wearing a seat belt," she says.

Even so, she has enjoyed the recent installation of a toilet in her home that separates urine (at the front) from other waste (at the back). The urine travels to a tank in her basement, which is pumped out a couple of times each year by a lorry that visits Williams and others in her area that take part in the project. "It's a nice change not dealing with the messy business of it. Making it easy for people is a biggie," Williams says.

Avoiding mess is also likely to help tackle the "ick factor" when it comes to peecycling, says Williams. "It's icky and it's smelly and it's something we don't talk about," she says. But while some may be put off by the idea of dealing with their own waste, REI's research suggests that the ick factor doesn't dominate people's reactions to peecycling. People tend to be open to the idea, Shupack says, but to think that others wouldn't be. "It's this assumption that everyone else is going to think it's really gross. That initial ick factor is not as big of a deal as people assume it's going to be," says Shupack.

Many people are, however, concerned about pharmaceutical content in the urine. "It's the biggest question we get," Shupack says. REI has conducted research to find out just how much of common drugs like caffeine and the painkiller acetaminophen are evident in vegetables grown using urine fertiliser. The final results are yet to be released, but the preliminary findings suggest the amount of pharmaceuticals in vegetables fertilised with urine to be "extremely small". "You'd have to eat a pretty obscene amount of lettuce, every day, for way longer than you can live" to get a cup of coffee's worth of caffeine, Shupack says.

Health worries and messiness aside, Williams points out that it is our Western attitude to waste that most urgently needs to change. "Particularly in [the US], people don't really think about where their waste goes. They think about it in terms of recycling and trash to some degree, but not so much in terms of human waste. It's a new frontier for people."

Climate change and water pollution can feel like impossibly big issues, but Williams doesn't let them overwhelm her. Instead, she focuses on what she can do in a small way, in her own home. "We can just do our part," she says. "We aren't perfect, but we try to at least be responsible in terms of what happens to our bodily waste." 

 

Surge in marine heatwaves costs lives and billions in storm damage – study. Floods, whale strandings and coral bleaching all more likely, say researchers, as 10% of ocean hits record high temperatures in 2023-24

 

A sperm whale died after stranding at Yeh Malet beach in Bali, in April 2023 – warmer ocean temperatures increase the risk of similar events. Photograph: Dicky Bisinglasi/AFP/Getty Images

 Sophie Kevany

 

The world’s oceans experienced three-and-a-half times as many marine heatwave days last year and in 2023 compared with any other year on record, a study has found.

The sustained spike in ocean temperatures cost lives and caused billions of dollars in storm damage, increased whale and dolphin stranding risks, harmed commercial fishing and sparked a global coral bleaching, according to the paper published on Friday in Nature Climate Change.

 

Like heatwaves on land, a marine heatwave is defined as a period of higher than normal temperature over a longer than usual time. The most recent of these were brought about by human-induced climate change and amplified by El Niño conditions, the report’s authors said, with nearly 10% of the ocean hitting record high temperatures in 2023-24.

“The more regularly our marine ecosystems are being hit by marine heatwaves, the harder it is for them to recover from each event,” said lead author Kathryn Smith from the UK’s Marine Biological Association.

Higher ocean temperatures “supercharge” evaporation, the study said, fuelling storms such as Cyclone Gabrielle which hit New Zealand in February 2023, killing 11 people and costing an estimated NZ$14.5bn (about £6.5bn).

One of the most surprising findings in the study, said Smith, was “how much [marine heatwaves] accentuated storms on land and the number of people that were hit by that – hurt, lost possessions, [suffered a] monetary impact or lost their lives”.

At least 45 people died in April last year when a dam burst in Kenya’s Rift valley, as torrential rains battered the country. Photograph: Luis Tato/AFP/Getty Images

 More worryingly, she said: “There is going to be a huge amount more [about the impacts of marine heatwaves] that we don’t know about [yet] because of the time it takes to publish in scientific literature.”

The effect on species was often devastating. Whales and dolphins venture closer to shore when the water is warm because they follow their prey, so this increased their chances of stranding, said Smith. For Mediterranean fan mussels, which have been dying in their millions since 2016, marine heatwaves may be the final nail in the coffin because the warming waters bring increased risk of diseases, the study said.

An aerial photo from February 2023 showing flooding caused by Cyclone Gabrielle in Awatoto, New Zealand. Photograph: AFP/Getty Images

Although human intervention saved some marine life from the recent heatwaves, the study found damage reduction was mostly lacking, possibly due to limited resources, disconnects between organisations and poor communication.

When there was time to prepare, successful mitigation actions included moving corals and conches in Florida to deeper, cooler water and keeping endangered Tasmanian red handfish in aquariums until they could be returned to the wild.

For corals, the study said initiatives to create new colonies using assisted sexual reproduction that increases genetic diversity showed potential, with increased resilience to bleaching “observed in trial populations of reef-building corals across the Caribbean and Mexico”.

Increased ocean temperatures can sometimes bring small wins, the study noted. In Peru, for example, while the anchovy catch was badly affected by the fish moving outside their normal range – a shift that led to commercial fishery closures and estimated losses of $1.4bn (£1.1bn) – squid landings increased.

 A juvenile queen conch. Scientists in the US moved some of the molluscs into cooler waters to protect them from the warming ocean. Photograph: Jennifer Doerr/NOAA SEFSC Galveston

 

Better forecasting, the study found, is critical to reducing damage from severe marine heatwaves, because it provides “greater confidence” for those making damage limitation decisions.

Valeria Pizarro, a scientist at America’s Perry Institute for Marine Science, who was not part of the study, said watching corals bleach “in the blink of my eyes” made her feel “very sad and frustrated”. In most cases, she said, the paper showed effective responses to marine heatwaves were lacking because “we weren’t prepared, we didn’t have the money or the manpower to do much in such a short period of time”.

More broadly, said Smith, the direct link between the climate crisis and ocean temperatures means that “until we see a switch from fossil fuels to renewable energy”, marine heatwaves, and the damage they do, will continue to increase. 

Total collapse of vital Atlantic currents unlikely this century, study finds. Climate scientists caution, however, that even weakened currents would cause profound harm to humanity

Global heating is weakening the Atlantic meridional overturning circulation (Amoc), which plays a crucial role in global weather conditions. Photograph: Henrik Egede-Lassen/Zoomedia/PA
 

Damian Carrington Environment editor

 

 

Vital Atlantic Ocean currents are unlikely to completely collapse this century, according to a study, but scientists say a severe weakening remains probable and would still have disastrous impacts on billions of people.

The Atlantic meridional overturning circulation (Amoc) is a system of currents that plays a crucial role in the global climate. The climate crisis is weakening the complex system, but determining if and when it will collapse is difficult.

Studies based on ocean measurements indicate that the Amoc is becoming unstable and approaching a tipping point, beyond which a collapse will be unstoppable. They have suggested this would happen this century, but there are only 20 years of direct measurements and data inferred from earlier times bring large uncertainties.

 

Climate models have indicated that a collapse is not likely before 2100, but they might have been unrealistically stable compared with the actual ocean system.

The latest study is important because it uses climate models to reveal the reason that the Amoc is more stable: winds in the Southern Ocean continuing to draw water up to the surface and drive the whole system. The study does not rule out an Amoc collapse after 2100, and other modelling research suggests collapses will occur after that time.

“We found that the Amoc is very likely to weaken under global warming, but it’s unlikely to collapse this century,” said Dr Jonathan Baker at the UK’s Met Office, who led the latest study. He said it was reassuring that an abrupt Amoc crash was improbable, and that the knowledge could help governments plan better for future climate impacts. Amoc weakening would still bring major climate challenges across the globe however, with more floods and droughts and faster sea level rise, he added.

“Of course, unlikely doesn’t mean impossible,” he said. “There’s still a chance that Amoc could collapse [this century], so we still need to cut greenhouse gas emissions urgently. And even a collapse in the next century would cause devastating impacts for climate and society.”

Prof Niklas Boers at the Potsdam Institute for Climate Impact Research (PIK) in Germany said the study delivered a substantial improvement in the understanding of Amoc. “But even a weakening that is not due to a tipping point could have similarly severe impacts on, for example, tropical rains,” he said. “One could even go as far as saying that, in the short term, it doesn’t really matter if we have a strong weakening, say 80%, or a collapse.”

The Amoc system brings warm, salty water northwards towards the Arctic where it cools, sinks, and flows back southwards. Global heating, however, is pushing water temperatures up and increasing the melting of the huge Greenland ice cap, which is flooding the area with fresh water. Both factors mean the water is less dense, reducing sinkage and slowing the currents.

The Amoc was already known to be at its weakest in 1,600 years as a result of global heating, and researchers spotted warning signs of a tipping point in 2021. The Amoc has collapsed in the Earth’s past, Baker said. “So it’s a real risk.”

A collapse of Amoc would have disastrous consequences around the world, severely disrupting the rains that billions of people depend on for food in India, South America and West Africa. It would increase the ferocity of storms and send temperatures plunging in Europe, while pushing up sea levels on the eastern coast of North America and further endangering the Amazon rainforest and Antarctic ice sheets. Scientists have previously said a collapse must be avoided at all costs.

The latest study, published in the journal Nature, used 34 state-of-the-art climate models to assess the Amoc. The researchers used extreme conditions – a quadrupling of carbon dioxide levels or a huge influx of meltwater into the North Atlantic – so that the changes in the modelled ocean currents were clear.

They found that while the Amoc slowed by between 20% and 80% this century, it did not collapse completely in any of the models. This was because winds in the Southern Ocean continued to draw water up to the surface. Balancing this, to the scientists’ surprise, were new downwelling areas in the Pacific and Indian oceans, but they were not strong enough to wholly compensate for the slowing of the Amoc, leaving it significantly weakened.

“Even just a 50% reduction in strength would result in a large drop in heat transport that would alter regional and global climates,” said Dr Aixue Hu at the Global Climate Dynamics Laboratory in Colorado, US. “There is therefore no reason to be complacent about Amoc weakening, and every effort must still be made to combat the global warming that drives it.”

Prof Stefan Rahmstorf, an Amoc expert at PIK, said the latest study considered a collapse to be the total cessation of the currents in the North Atlantic, while previous studies have termed a greatly weakened Amoc a collapse.

Amoc is partly driven by the sinking of dense water and partly by winds, and the latest study provides particular insights on the latter. “It does not, however, change the assessment of the risk and impact of future Amoc changes in response to human-caused global warming, as that is linked to the [density-driven] part of Amoc,” Rahmstorf said. His own research on post-2100 Amoc collapse, currently under review, concludes “a collapse cannot be considered a low-probability event any more”.

Despite the revelations in the latest study, the extent of future Amoc weakening and the timing of any collapse remain uncertain. “There’s a huge amount of work left to do, because there’s still a huge range across models in how much Amoc will weaken,” Baker said, with increasing the resolution of models one important requirement.

“We also show that the Southern Ocean and the Pacific Ocean are more important than we thought for Amoc, so we need better observations and modelling in those regions. That’s crucial to improving the projections so we can better inform policymakers,” he said.

 

Extreme weather expected to cause food price volatility in 2025 after cost of cocoa and coffee doubles

 

Chocolate being added to cups of coffee. The prices for cocoa and coffee rose 163% and 103% respectively in the year to January. Photograph: Luca Bruno/AP

 Damien Gayle

 Trend towards more extreme-weather events will continue to hit crop yields and create price spikes, Inverto says

 

Extreme weather events are expected to lead to volatile food prices throughout 2025, supply chain analysts have said, after cocoa and coffee prices more than doubled over the past year.

In an apparent confirmation of warnings that climate breakdown could lead to food shortages, research by the consultancy Inverto found steep rises in the prices of a number of food commodities in the year to January that correlated with unexpected weather.

Several authorities declared 2024 the hottest year on record, a trend towards higher temperatures that seems to be continuing into 2025. Inverto said a long-term trend towards more extreme weather events would continue to hit regional crop yields, causing price spikes.

The highest price rises were for cocoa and coffee, up 163% and 103% respectively, due to a combination of higher than average rainfall and temperatures in producing regions, according to the research.

 

 

 

Sunflower oil prices increased by 56% after drought caused poor crop yields in Bulgaria and Ukraine, which also continued to be affected by the Russian invasion. Other food commodities with sharp year-on-year price rises included orange juice and butter, both up by more than a third, and beef, up by just over a quarter.

“Food manufacturers and retailers should diversify their supply chains and sourcing strategies to reduce over-reliance on any one region affected by crop failures,” Katharina Erfort, of Inverto, said.

 

In December, the UK government said climate breakdown and related food price inflation was leading to a rise in the number of hungry and malnourished households.

Climate scientists said Inverto’s findings were in line with their expectations.

“Extreme weather events around the globe will continue to increase in severity and frequency in line with the ongoing rise in global temperature,” said Pete Falloon, a food security expert at the Met Office and University of Bristol.

 

 

 

“Crops are often vulnerable to extreme weather, and we can expect to witness ongoing shocks to global agricultural production and supply chains, which ultimately feed into food security concerns.”

Max Kotz, of the Potsdam Institute for Climate Impact Research, said data showed heat extremes were already directly affecting food prices.

“Last year showed numerous examples of this phenomena playing out in real time, as extreme heat across east Asia drove substantial increases in the price of rice in Japan and vegetables in China,” he said.

“Market commodities were also strongly affected, with extreme heat and drought across cocoa-producing west African countries and coffee-producing regions in Brazil and Vietnam driving strong increases in prices. Until greenhouse gas emissions are actually reduced to net zero, heat and drought extremes will continue to intensify across the world, causing greater problems for agriculture and food prices than those we are currently facing.”