Författare: Jack Marley Environment Energy Editor UK edition

Beavers, those iron-toothed rodents with a talent for hydraulic engineering, can legally return to English river catchments after an absence of 500 years.

Castor fiber has been on the way back for the last two decades thanks to unauthorised reintroductions. But until a few weeks ago, an enclosure was the only home these semi-aquatic mammals could legally find in the UK.

Successive governments have hesitated to issue release licenses for beavers, given their ability to transform the environment in unpredictable ways. When it comes to mitigating and adapting to climate change, however, that’s their biggest asset.

This roundup of The Conversation’s climate coverage comes from our award-winning weekly climate action newsletter. Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. Join the 40,000+ readers who’ve subscribed.

When the reign of Tyrannosaurus rex abruptly ended 66 million years ago, a “prehistoric beaver” was on the ascendancy according to Stephen Brusatte, a palaeontologist at the University of Edinburgh.

“It wasn’t a good time to be alive,” he says. An asteroid had smashed into Earth with the equivalent fury of several million nuclear bombs. But Kimbetopsalis simmonsae, with its buck-toothed incisors and appetite for leaves and branches, survived.

Within a few hundred thousand years, lush forests had returned. Filling the vacant niches left by vanished dinosaurs were mammals like Kimbetopsalis.

“This burst of evolution led to primates, which eventually led to us,” Brusatte says.

Beaver-like ancestors braved a mass extinction event to help mammals rise from the ashes. What could modern beavers do during another era of planetary crisis?

Read more:
How we found ’prehistoric beaver’ that helped mammals inherit Earth after dinosaurs were wiped out

Dam the carbon

Legal protections and synthetic materials that reduced demand for warm fur have allowed beavers to regain their former haunts in Europe and North America.

The famously industrious rodents have wasted no time in picking up where they left off: damming streams to create ponds in which they build their dome-like lodges, safe from predators that might prowl the banks opposite.

A beaver lodge on a lake near Bad Freienwalde, north-eastern Germany.
Ebenart/Shutterstock

This behaviour has a stunning effect on the surrounding environment – perhaps even the climate. That’s because beaver dams trap vast quantities of sediment rich in carbon that might otherwise heat the atmosphere, says Christine E. Hatch, a professor of geosciences at UMass Amherst.

Read more:
Beavers offer lessons about managing water in a changing climate, whether the challenge is drought or floods

You should take this good news with a pinch of silt, however. CO₂ emissions from human activity were probably well over 40 billion tonnes last year – another annual high. Expecting beavers to offset our emissions is unrealistic, not to mention unreasonable.

Beavers may be skilled at stowing carbon in the wetlands they create, but this advantage is being undone by feedback mechanisms kickstarted by climate change. For example, the warming Arctic is inviting beavers to expand northwards. Here, their antics threaten to speed up the thawing of permafrost that has kept world-warming methane locked up says Helen Wheeler, a lecturer in wildlife ecology at Anglia Ruskin University.

Read more:
Arctic heatwave: what warmer summers mean for the region’s wildlife

Shelter from the storm

Where beavers really shine is in their knack for soothing damaged landscapes.

“Renowned engineers, beavers seem able to dam any stream, building structures with logs and mud that can flood large areas,” Hatch says.

“As climate change causes extreme storms in some areas and intense drought in others, scientists are finding that beavers’ small-scale natural interventions are valuable.”

The changes beavers make can help land hold onto water and release it slowly, which eases flooding and stalls drought. Compare this with human design innovations like tarmac, which radiates heat and allows storm water to slough off in torrents.

While the concrete dams that people construct bar the way for migratory freshwater fish, some of Earth’s most threatened animals, beaver dams present no such obstacle.

“One reason may be that the fish can rest in slow pools and cool pond complexes after navigating the tallest parts of the dams,” Hatch says.

Beaver wetlands do excel in blocking one thing, however: wildfires.

“Recent studies in the western US have found that vegetation in beaver-dammed river corridors is more fire-resistant than in areas without beavers because it is well watered and lush, so it doesn’t burn as easily,” Hatch says.

All of these qualities make beaver wetlands a fantastic refuge for a range of wildlife, particularly as ecosystems nearby are wracked and warped by rising temperatures and extreme weather. Even our towns and cities could be made more liveable with their help, as water evaporating from these ponds cools the air during heatwaves and absorbs flood water during a deluge.

Geographers Joshua Larsen (University of Birmingham), Annegret Larsen (Wageningen University) and Matthew Dennis (University of Manchester) are slightly more cautious.

“Unless the water bodies are very large, or high in number, this [effect] tends to diminish rapidly with distance from the water. This would make it difficult to rely upon beaver ponds for cooling benefits for human settlements,” they say.

Read more:
Beavers can do wonders for nature – but we should be realistic about these benefits extending to people

Nonetheless, allowing beavers to recover a fraction of their former abundance will make the effects of global heating less severe.

“Beavers are showing that their impacts can offer added levels of ecosystem resilience to a changing climate that we would be wise to embrace,” they add. Läs mer…

“The biggest challenge to limiting climate change to 2°C, the upper target of the 2015 Paris agreement, is this: methane emissions are rising very fast,” says Euan Nisbet, a professor of earth sciences at Royal Holloway University.

If each CO₂ molecule is like a candle that patiently warms the atmosphere, methane is like an exploding bomb: responsible for much more heat, but over a much shorter timescale. Satellites are identifying the methane that’s leaking from oil wells and gas pipelines, and most countries have at least promised to reduce these emissions by a third by 2030.

But if humanity is to throw the brakes on runaway climate change, something has to be done about the biggest human source of methane there is: agriculture.

This roundup of The Conversation’s climate coverage comes from our award-winning weekly climate action newsletter. Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. Join the 40,000+ readers who’ve subscribed.

Taming methane

Earth’s atmosphere is warmer and wetter than it would otherwise be, thanks to fossil fuel burning. This is inducing wetlands, once a reliable carbon store, to emit more methane to the atmosphere, and so speed up climate change, Nisbet says.

Read more:
Methane emissions are turbocharging climate change – these quick fixes could slow it down

This makes it even more urgent to tamp down the methane sources under our immediate control. Nisbet has calculated that roughly 210 million to 250 million tonnes of methane come from agriculture and its products. Most of this is in the breath of livestock animals and their manure, and food rotting in landfills.

Here’s the good news.

“Cutting agricultural methane emissions involves a wide range of relatively cheap measures that need good design and management, but could cut food-related emissions substantially over the next decade,” Nisbet says.

Adding a layer of soil to a landfill provides habitat for methane-munching bacteria. Covering manure storage tanks, banning the burning of crop waste and only flooding rice paddies when necessary could pinch other methane sources.

Reducing food waste would also cut methane emissions.
AleksB59/Shutterstock

These aren’t expensive or difficult changes, Nisbet says. It might cost more to vaccinate cattle or breed them to produce more female calves, however. The point with both measures is to have smaller herds for the same quantity of beef and milk.

Lower consumer demand would also shrink these methane mobs (here’s where you come in, dear reader). If more of our essential nutrients like protein came from beans instead of meat, our health would benefit along with the climate. While nutritionists and environmental scientists urge us to eat more fruit and vegetables, the global food system is stacked against this outcome.

Read more:
Meat and dairy gobble up farming subsidies worldwide, which is bad for your health and the planet

Globally, every fifth dollar of public farming subsidy goes towards rearing meat. In the intensively farmed UK where I live, 85% of farmland is devoted to livestock and the crops that feed them. Yet these captive animals are the source of less than one third of our calories.

“The longer the livestock-intensive system prevails, the greater the environmental, economic and social costs,” says Benjamin Selwyn, a professor of international development at the University of Sussex.

The fruits of our labour

Selwyn favours a “green new deal” that would make farming “complement rather than undermine the environment”.

Read more:
The UK’s food system is broken. A green new deal for agriculture could be revolutionary

What does that look like? Fewer cows, more woodland and more crops grown for human consumption, Selwyn says. This is essentially what government advisers recently proposed to keep the UK on track for net zero emissions.

Read more:
The UK must make big changes to its diets, farming and land use to hit net zero – official climate advisers

To nudge the food system in this direction, researchers like Yi Li, a senior lecturer in marketing at Macquarie University, are testing the effect of labels on meal choices.

In Australia, where Li is based, meat accounts for half of all greenhouse gas emissions from products consumed at home. Producing 1kg of beef may emit 60kg of greenhouse gas, while the same quantity of peas yields just 1kg of emissions. But Li found consumers weren’t always savvy to the gulf in emissions between the two.

“Our label creates a mental link between a food source and its carbon impact,” she says.

“When a consumer sees high carbon scores and red traffic lights appearing more frequently on meat and other animal products, they begin to make the connection between those products and higher emissions.”

Read more:
Want a side of CO₂ with that? Better food labels help us choose more climate-friendly foods

While better informed consumers are important, the food system needs deeper reform.

“Many conceptions of the protein transition from animal sources to more plant products ignore the necessity of improving farmers’ and agricultural workers’ incomes. But this will be crucial,” Selwyn says.

Just as oil and gas workers will need financial support and training opportunities to ply their skills in a low-carbon energy sector, farm workers will need security and guidance to adapt to new forms of food production says Alex Heffron.

Read more:
The UK farmer protests you probably haven’t heard about

Heffron, a PhD candidate at Lancaster University, researchers agricultural transitions and is a farm worker himself. He says that people picking crops, milking cows and driving farm machinery are among the most exploited and precariously employed of the UK’s workforce.

Seasonal farm workers often live where they work, raising the risk of abuse.
Pavel Tarin Alcala/Shutterstock

In fact, if the country were to begin phasing out livestock and ramping up fruit and vegetable production tomorrow, the burden would fall heavily on migrant labourers who the UK attracts with a seasonal worker scheme. This scheme has been criticised for overlooking allegations of forced labour.

“There will be no green transition unless these workers have a stake in it,” Heffron says.

What kind of stake might move farmers away from steak? Selwyn has some suggestions, which include spreading land ownership more evenly with community land trusts and allowing public bodies to acquire vacant, derelict or damaged land for allotments and nature habitat.

“Farms can be paid directly by government for sustainable production to combat farmer poverty,” he adds. “And the real living wage of £12.60 an hour should be compulsory for agricultural workers.” Läs mer…