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An inconspicuous corner of East Anglia is well and truly alive. Norfolk's patchwork of fields, fens and scraggy marshes is home to a handful of species seldom found elsewhere in the UK, but these delicate ecosystems are facing an existential threat from climate change.
In the marshlands to the east of Norwich, a flock of taiga bean geese – the last left in England – waits for the Arctic winter to draw to a close before heading back to its breeding ground in Siberia. In summer, the Norfolk Broads are dotted with the black and yellow stripes of the largest native butterfly in the UK, the British swallowtail. This subspecies is only found in Norfolk’s fenland, close to the milk parsley – the only food its larvae can stomach. In the hedgerows and woodlands dotting the county, a handful of bumblebee species are largely responsible for maintaining the area’s smattering of wildflowers.
But the days of the species are already numbered. Using climate change models, Jeff Price, a biodiversity researcher at the University of East Anglia in Norwich has compiled a list of Norfolk-based species that are unlikely to stick around if global temperature increases carry on as projected. There are 13 bumblebee species on Price’s list, as well as 24 birds, 15 trees and some 270 moths that could vanish altogether if global temperatures rise by 3.2 degrees centigrade. “If nothing else it’s a wake up call that we need to be monitoring these species,” he says.
None of these predictions are set in stone, however. Working out the impact of climate change is a notoriously tricky business. First, environmental scientists like Price have to model how global temperature increases will change the weather in a given area, predicting factors like average temperature highs and lows as well as the amount rainfall in a given time period. Then they have to take those models and match them up with the known climate ranges for existing species. If the summers are warmer and the winters wetter, they might ask, is Norfolk still the kind of place you’re likely to find swallowtail butterflies or heath bumblebees?
What we do know is that the days of this fragile landscape are already numbered. As global temperatures continue to steadily creep upwards and extreme weather events become more common, Norfolk’s delicate ecosystems are slowly spinning out of balance, one species at a time.
The bumblebees will be first to go. As the year 2050 passes, and – if current projections are accurate – we slide past the two degrees centigrade temperature increase agreed upon the Paris climate accord, these key pollinators will start to feel the pressure of climate change. Worker bees live for just five or six weeks, and spend much of their time bringing back pollen and nectar to feed young in their colony or gathering plant resin to reinforce their nest.
In heat waves, they find themselves too dazed to fly properly. “They really get kind of dopey and incapable of moving reliably and safely,” says Jeremy Kerr at the University of Ottawa in Canada. As the decades march on, the number of deadly heat waves is set to increase. By the year 2100, up to 74 per cent of the world’s population is projected to experience more than 20 days of lethal heat levels every year. And heat levels that are lethal to humans aren't good news for bees either.
With worker bees out of action, their nests are no longer as well-provisioned and will become unable to breed healthy queen bees. Queens are the only bumblebees that can reproduce so if a nest isn’t able to provide new ones the overall number of colonies will start to dwindle. After 15 years in decline, the bumblebees may eventually die out altogether, their colonies slowly ground down by year after year of intense hot spells.
With their chief pollinators gone, the Norfolk wildflowers will start to dwindle too. “It’s almost unimaginable to picture an ecosystem without its keystone pollinators,” says Kerr. “[Bees] are by far the most effective pollinators that exists – there is no other group of animals that is as good or as specialised as bees.”
Between two thirds and three quarters of plant species are pollinated by insects, and bees are chief among them. Without a full range of pollinators, Kerr says it is unlikely that plants would be able to reproduce as effectively. Instead, species such as ragweed that disperse their pollen on the wind start to claim the territories left behind by the wildflowers. Springtime walks lifted by splashes of bloom will become dominated by shades of yellow, brown and green.
Around the same time that the bumblebees fall silent, Norfolk’s butterflies will die out too. The British swallowtail – already a rare sight before climate change started to take hold – may slowly become less common until it’s gone altogether. Some species spend winter in a state of suspended animation, but brief snaps of warm mid-winter weather trick butterflies into coming back to life and burn precious energy before a return to colder weather kills them off.
“Butterflies are so dependent on temperature and the environment,” says Osgur McDermott-Long, a butterfly researcher at the University of East Anglia, “their movement really depends on the weather.” Species such as the swallowtail that spend the winter as pupae or eggs are also vulnerable to viruses and other pathogens that grow faster in warmer weather. As with the bumblebees, the falling number of butterflies doesn’t chart a gentle downward slope but dips and rises with the weather. In bad years, the one-two punch of an extreme cold snap combined with a warmer overall winter knocks the number of butterflies in particular species down by as much as 50 per cent. In steadier years, the population could slowly claw back some ground, but over decades the butterfly species once at home in Norfolk – orangetips, ringlets and peacocks – could disappear altogether.
European butterflies that might be able to fill the gap left by departing species may not be able to cross the English Channel and establish themselves in the UK. “A species has to come over in a big enough population in order to establish itself,” says Price. For butterflies like the swallowtail, leaving Norfolk would be just a small part of a much wider decline across the whole of Europe as temperatures across the continent soar, and less mobile species fail to stay ahead of warmer climates edging further north year by year. Unable to keep pace with the changing climate, most of Norfolk’s butterflies will stay where they are, in ever smaller numbers, until one day they simply aren't there anymore.
For people living in the village of Buckenham, eight miles to the east of Norwich, one change will be more noticeable than most. One year, the flock of taiga bean geese that currently spends its winters just outside the village stops visiting altogether. No longer forced to travel so far from its Siberian breeding grounds in search of warmer climes to spend the winter, the flock may chose to winter in mainland Europe instead. The birds stop several times during their yearly migration, each time taking subtle clues from their environment, assessing temperature, food supply and habitats, to work out whether they’ve found the perfect place to spend the winter. “If conditions are good enough where they are, then they’re not going to expend unnecessary energy on crossing over the ocean,” says Daniel Hayhow at the Royal Society for the Protection of Birds.
The taiga bean won’t be alone in their shift eastwards. A study published in 2008 found that the overall centre of population of seven wader species had shifted to the north east by 115 kilometres over 30 years of migration. As the whole of Europe slowly warms up, increasing numbers of bird species are finding themselves able to spend the winters much closer to their breeding grounds.
Most animals, however, don’t have the option to fly to more suitable habitats. Hemmed in by roads and natural barriers, some mammals will be forced to adapt to the changing temperatures and more frequent extreme weather events. Many won’t survive. “It would be an insidious loss – mortality would exceed breeding rate year after year after year,” says Chris Newman, a zoologist at the University of Oxford. Species like deer, which tend to only eat a limited range of food, mainly brambles, herbs and tree shoots, are particularly vulnerable to changes in temperature. If the summers are too hot, the forage the deer usually eat becomes dry and they eat less, making them more vulnerable to disease and death.
Other mammals, however, will adapt and thrive in the new climate. Globally, in the event of a two degrees temperature increase, about half the species in a given area will stay the same, says Price. Between 25 and 50 per cent of species will either leave an area or die out altogether, while the number of new species entering the area increases by 25 per cent. “You end up with fewer species and substantial numbers of those being different,” Price says. Newman agrees: “What’s forgotten about climate change is that animals are adaptable.” Badgers in Spain and Italy already eat olives, so if the climate in Norfolk becomes suitable for olive groves, local badgers should be able to change their diet to suit the new environment. “They will adapt, they won’t just roll over and say ‘the weather’s no good anymore.’”
Although the Norfolk case study gives us a broad idea of how climate change might impact a handful of ecosystems, it’s impossible to really know how much the countryside will change over the next century. “There are many things that we cannot project and we cannot model,” says Hayhow. Climate change models can estimate how the habitat range of certain species will change over the years, but they can’t tell us what will happen when a new species moves into an area already inhabited by a competitor. Faced such an uncertain future, the best we can do is make sure we help maintain as many different habitats as possible to help accommodate a diverse range of creatures. In Norfolk, this will mean preserving hedgerows, protecting vulnerable areas of coastline and making sure that the area’s ancient forests are maintained.
“We don’t really know what will happen beyond an increase of two degrees, or beyond the next 50 to 80 years,” Hayhow says. “But there is going to be change, and we need to accommodate this change.” For Hayhow and his fellow conservationists, this means preparing for the changes that they can predict, while accepting that the environments they work so closely with may change beyond recognition over the next century.
This article was originally published by WIRED UK
