Meltwater flushed frozen methane hydrates out of the sediment at the edge of the Greenland ice sheet after the last glacial maximum, which occurred 29,000 to 19,000 years ago, raising fears that melting glaciers could soon release huge amounts of this planet-warming gas.

Methane hydrates form when gas molecules are trapped in a cage of water molecules, freezing into an ice-like substance. They are sometimes called “fire ice” because they can despite being 85 per cent water.

They form under the high pressure and low temperature found in sediments beneath the ocean, permafrost or glaciers. Some suggest methane hydrates contain twice as much carbon as all coal, oil and conventional gas on Earth.

But global warming is disrupting some of the cold, pressurised conditions in which methane hydrates exist. For example, some scientists think a mysterious 50-metre-deep discovered in the Russian Arctic in 2014 was caused when permafrost thaw suddenly relieved the pressure on a methane hydrate. This would have released it in a “violent physical explosion”, wrote the authors of .

Now, researchers have found that flows of glacial meltwater in Greenland can also unleash methane hydrates. “We found a new way of releasing methane that we thought was in the bank,” says at the University of Manchester, UK, who led the research. “It is methane we thought was stable.”

Huuse and his colleagues knew methane hydrates were common in the spaces between grains of sediment at the bottom of Melville Bay in north-western Greenland. In seismic surveys done by oil and gas companies in 2011 and 2013, they noticed 50 large pockmarks in the seafloor, each up to 37 metres deep, clustered near a long berm of earth called a grounding zone wedge. During the last glacial maximum, this wedge was where the floating tongue of the ice sheet met the ocean bottom.

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The researchers initially thought the pockmarks had been scoured by overturning icebergs. But when they drilled sediment cores in the area, they found the top layers of sediment were mostly free of methane, even though the temperature and pressure were perfect for methane hydrates.

They also found large volumes of fresh water in the sediments, rather than the seawater they expected. This could only have come from ice sheet melt. The team thinks that during the last glacial maximum, meltwater flowing under the glaciers in Melville Bay was forced through the grounding zone wedge, flushing out the methane hydrates.

In the future, meltwater could wash out hydrates at the edges of other glaciers as they retreat under climate change, says Huuse. Similar grounding zone wedges exist across the Arctic.

“In the not-so-distant past – could be 12,000, could be 15,000 years ago – a large amount of methane was released, and that same thing could happen tomorrow or in the next century, basically, of receding ice sheets,” he says. “And that’s bad news, because it’s not something we’d considered before.”

The research didn’t include an estimate of how much methane was released in Melville Bay, but Huuse figures it could have been on the order of 130 million tonnes. That’s the equivalent of about two years of from the US, although he notes this methane could have been released over the course of a century, rather than a year or two, and it was a one-time emission.

In addition, the methane would have been dissolved in seawater and, depending on the saturation, it may not all have been emitted to the atmosphere, he says.

The Antarctic ice sheet probably sits on top of even more methane hydrates than Greenland. The polar regions as a whole are to hold anywhere between 100 billion to 760 billion tonnes of methane in subglacial and marine hydrates. The release of even a fraction of that could rival the 48.7 million tonnes of methane currently released by the Arctic and boreal biomes each year – mostly from wetlands, lakes and streams – and speed up climate change.

Methane is already being unlocked from under the Greenland ice sheet. A published this month found meltwater streams across western Greenland are emitting an estimated 715 tonnes of methane per year. While some of this could be coming from hydrates, it is more likely to come from ancient plant carbon converted to methane gas by bacteria under the ice, says at the UK Centre for Ecology and Hydrology, who led the study. This will probably increase.

“If you’re getting enhanced melt, you’re potentially tapping into areas of subglacial system that… have got well-preserved organic carbon stocks that then have the potential to be converted into methane,” she says. “There is the potential of relatively large future release.”

David Attenborough is inarguably one of the UK’s national institutions. He consistently tops polls for the most popular and trustworthy celebrity in the country. There will never be another broadcaster quite like him – but that’s OK.

Attenborough, who turns 100 on 8 May, began his career in nature broadcasting in 1954 with , in which staff from London Zoo went to tropical countries to capture exotic animals and return them to the UK. It was very much a product of its time, but so was Attenborough. He was at the forefront of a new medium (only a third of UK households had a TV when Zoo Quest was first broadcast) and defined the template for nature documentaries, most notably with his 1979 series.

People often ask who might replace him, but the truth is, the niche that allowed him to evolve – a dominant broadcaster in the BBC and a cohesive culture enforced by a lack of choice in viewing material – no longer exists. Instead, the rise of social media has seen a Cambrian explosion in science communicators, each adapting to their environment.

The truth is, the niche that allowed Attenborough to evolve no longer exists

There are pros and cons to this. From TikTok to YouTube to podcasts, we are now able to find a format that works for us, freed from a linear TV schedule. A far more diverse range of voices have been able to flourish, and people who are turned off by Attenborough (even if they don’t want to admit it in polite company) have many more presenters to choose from.

But this fragmentation also has its downsides. TV editors no longer determine what we see on our screens. They have been replaced by algorithms that often reward dopamine quick-hits rather than more in-depth work. While many science creators are a stickler for facts, like Attenborough, misinformation can also bloom unchecked. Plus, with no one ever watching quite the same thing, we have lost part of our shared culture.

Thankfully, Attenborough’s programmes remain available today, with many still as relevant as ever. Check out this round-up of our favourites, and pick something to watch in celebration of his centenary.

by Megha Mohan

by Jamie Bartlett

The best new popular science books of 2026

Clear out your shelves for a bumper new crop of books by authors including Naomi Klein, Rebecca Solnit and Xand Van Tulleken, says culture editor Alison Flood

by Suzanne Simard

by Michael Bond

by Kirsty King

by David George Haskell

by Rebecca Solnit

The best new popular science books of February 2026

Readers are spoiled for choice when it comes to popular science reading this month, with new titles by major names including Maggie Aderin and Michael Pollan

by Lixing Sun

by Katrina Manson

by F. Marina Schauffler

Let’s start off with a fact: you do not, no matter what you’ve heard, . At least, not in the course of a normal human diet. But this popular claim has raised alarm, especially as it has been followed by a flurry of studies that have found microplastics accumulating everywhere – even on the , in the and in the most – as well as in human heart tissue, livers, kidneys, breast milk and the bloodstream. If they are all over the place, and we can show in some scientific studies that they can lead to some sort of harm, that’s cause for major concern, right? Well, no, not necessarily.

The reason microplastics are effectively everywhere is that plastic is truly a marvel. The advent of the first plastic, Bakelite, in the early 20th century ushered in an age of materials manufactured on demand instead of being harvested from nature. As plastics became thinner and cheaper, they spread far and wide, revolutionising food packaging, electronics and medical devices, to name just a few things. But their durability has a downside. Tiny particles have been shedding into the environment for more than a century, and they last a long time, which is why they’ve been found in the body tissues and bloodstream of animals up and down the food chain – – and in , such as salt, beer and drinking water.

Exposure to microplastic makes animals want to eat it more

Over multiple generations, small nematode worms began preferring microplastic-contaminated food over cleaner options, which could have consequences for ecosystem health

So yes, microplastics are probably in you. But don’t fret just yet. When we think about any kind of pollutant in the body, we need to consider several things. Firstly, there is the question of size, and for microplastics, there is a huge range. Then there’s what dosage would show any effect. And finally, whether that effect is actually harmful. As many of the studies involve animals, we also need to ask whether those animal studies can reasonably apply to the average human.

The credit card claim

For microplastics, many of the most worrisome headlines in the news in the past few years have been vague about the size of the microplastics in question, or have relied on studies using outlandishly large doses that are unlikely to reflect day-to-day reality.

The , and has seemingly stuck around, was that on average every person on the planet is ingesting as much as 5 grams of microplastics per week – or the equivalent of a credit card’s worth. It came from a 2019 study that used some really shoddy maths, and it’s simply not true unless you’re taking a very unusual approach to curbing your spending.

One study found that most of the world’s population ingests just 0.0041 milligrams per week, which is less than a grain of salt

The study in question was financed by the World Wildlife Fund in partnership with the University of Newcastle. It was a review combining the findings of 59 previous studies on microplastics found in food and water. The problem is that some of the studies only measured the number of microplastic particles in a sample and others measured the mass of microplastics. This meant that the researchers had to rely on estimation in order to compare the two types of study. For example, they estimated the mass of microplastic particles found in drinking water using measurements from ocean water and particle counts per litre from drinking water. But microplastics in the ocean and our drinking water aren’t necessarily the same – if the average size of a microplastic particle in the ocean is much larger than those in filtered drinking water, the ultimate calculation will be inflated. Subsequent studies looking at the same data found that it was.

So, no, we don’t consume 5 grams of microplastics each week – it is likely far, far less. In fact, found that most of the world’s population ingests just 0.0041 milligrams per week, which is less than a grain of salt. At that rate, it would take you more than 1.2 million weeks, or more than 23,000 years, to plough through a credit card’s worth of plastic. If you’re immortal, go ahead and worry.

The same researchers did to predict that on average, each person will accumulate 12.2 milligrams of microplastics over the course of their life, but that only 41 nanograms will actually be absorbed by the body.

Fresh concerns have also been raised in the past few weeks over the quality of studies looking at the amount of microplastics in the body. For instance, some studies vaporise tissue samples and then analyse the fumes for the presence of microplastics. However, when fat is vaporised it can produce similar molecules, creating a false positive.

What do microplastics do in the body?

But all of that only addresses the amount of microplastics we consume. What they are doing to us is another question, and one we don’t have really solid answers for yet. Some evidence points to exposed to microplastics. But the highest dose given to those mice was 1 gram per day, which is astronomical for a human body, let alone a mouse. A study in pigs used 1 gram per week, and found that microplastics exposure affected the expression of 86 genes and induced oxidative stress in the pancreas, which is caused when there aren’t enough antioxidants in the body to get rid of unstable molecules that lead to cell damage. But again, the dosage is unrealistic. In fact, in 2022 the World Health Organization warned that most animal studies use concentrations of microplastics much higher than people are typically exposed to, or use larger microplastic particles than are likely to be taken up by the human body. The report also notes that microplastics circulate through our organs differently than they do in rodents, making it difficult to translate findings to humans.

Preliminary studies in humans do exist, and one recent study found that microplastics can accumulate in plaques along with fats, cholesterol and blood cells. In people who had these plastic-infused plaques, researchers saw a higher rate of heart attack and stroke – but we can only say these were correlated, and not that the microplastics themselves caused these outcomes.

Understanding what microplastics are doing to our bodies is complex. Yes, they contain chemicals that could disrupt our body processes, but when assessing the risk, we can’t assume that 100 per cent of those chemicals leach into our bodies instantaneously. Research has shown that when we assume an average amount of leaching in our gut, for example, it results in negligible increases in chemical . And these chemicals don’t necessarily increase over your lifetime, because they can also leach out of your tissues and exit through your faeces.

Concerns have been raised that other toxins attached to microplastics could be brought into the body. Or they could interfere with immune responses, or cause cell damage or inflammation. But do they cause these effects more than, say, other kinds of air pollution, sun exposure, eating excess sugar or getting a cold? We simply don’t know.

It is understandable to think that microplastics could possibly be dangerous to our health, and we should find out whether they really are. It is a claim that feeds into our doomerism feelings about the pollution happening all around us. And just because we don’t consume a credit card’s worth of plastic every week doesn’t mean the underlying concerns aren’t valid. But the field is still young, and we don’t yet have rigorous data on the effects of microplastics in the body. So I would spend my time worrying about other things until we have more solid research on the effects of microplastics.

The 91av Book Club has been reading Tim Winton’s novel Juice this month, a blistering tale set in a far-future Australia where the heat is driving humanity to its limits. Winton talked to our sci-fi columnist Emily H. Wilson about everything from what it’s like to live through extreme heat at his home in north-west Australia to how a lifetime of environmental activism and writing led him to finally write this novel. Winton also shared how it feels to not yet have a publisher in the US for this important tale of climate change and retribution.

Read more: Read an extract from Juice by Tim Winton

More than 60 years after Rachel Carson warned of the dangers of pesticides in her book Silent Spring, the harm they are doing to wildlife may be greater than ever.

“In more or less all countries, the trend is towards increasing applied toxicity,” says at RPTU University Kaiserslautern-Landau in Germany.

The potential harm done by any pesticide depends on both the amount applied and its toxicity, which can vary greatly from species to species. To assess the overall burden of pesticides, Schulz and his colleagues have developed a measure called applied toxicity.

The researchers started by looking at the quantities of 625 pesticides used in 201 countries from 2013 to 2019. The list includes some pesticides used by organic farmers as well as conventional ones.

They then averaged data from regulators in several countries on how toxic each pesticide is to eight broad groups of organisms: aquatic plants, aquatic invertebrates, fish, terrestrial arthropods, pollinators, soil organisms, terrestrial vertebrates and terrestrial plants. This allowed the team to estimate the total applied toxicity per country or per group of organisms.

Globally, the total applied toxicity rose from 2013 to 2019 for six of the eight groups of organisms. For instance, for pollinators it rose 13 per cent, for fish 27 per cent and for terrestrial arthropods, such as insects, crustaceans and spiders, 43 per cent.

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“This does not mean that this toxicity necessarily translates into toxic actions on these organisms,” says Schulz. “But it’s at least an indicator that shows you if the pesticides we are using are more or less toxic to pollinators or to fish, or to whatever.”

Many other studies have found that the concentrations of pesticides in various environments, such as rivers, are higher than regulators assessed were possible when approving the pesticides.

“This is not included in this index, but there’s a lot of evidence,” says Schulz. There is a problem with risk assessments greatly underestimating exposure, he says.

The increases in total applied toxicity are due to two things: an increase in the quantities of pesticides being used and the replacement of older pesticides with ones that are even more toxic. In turn, this is mainly due to the evolution of resistant pests. “Resistance is, in my view, something that can only increase if you use chemical pesticides,” says Schulz.

Pesticides called pyrethroids are particularly problematic, especially for fish and aquatic invertebrates, he says, even though they are only supposed to be applied at low levels. Neonicotinoids are another problematic group, especially for pollinators.

There have been calls to ban the herbicide glyphosate, also known as the weedkiller Roundup. Although its toxicity isn’t high, because large quantities of glyphosate are used, it does contribute to the total applied toxicity, says Schulz. A ban could also backfire: the applied toxicity would increase if more toxic herbicides were used instead.

Is the climate change food crisis even worse than we imagined?

Extreme weather and a growing population are driving a food security crisis. What can we do to break the vicious cycle of carbon emissions, climate change and soaring food costs – or is it already too late?

Reducing pesticide usage more widely could have unintended consequences, too. If it reduced the productivity of farms, more farmland would be needed, leading to biodiversity loss if land is cleared.

At a UN biodiversity summit in 2022, countries agreed to reduce the by at least half by 2030. Exactly what “risk” means was never defined, says Schulz, but he thinks total applied toxicity would be one way to measure it.

The approach has its limitations, but no measure of overall pesticide use will be perfect, says at Utrecht University in the Netherlands. “Even with uncertainty, the trends it reveals are troubling,” he says. “The world is currently moving away from the UN target rather than toward it. That is bad news for ecosystems and ultimately for human health.”

“Importantly, the study also shows that a relatively small number of highly toxic pesticides drive most of the overall risk, which means there are clear, practical targets where action could have an outsized benefit,” says Vermeulen.

Transforming farming will require a broader societal shift, he says. “Consumers must be willing to accept changes in diets, reduce food waste and pay fair prices that reflect the true environmental costs of production.”