Climate change and extinction
In early September 2004, Charles Monnett flew out of the Alaskan capital of Anchorage in a light aircraft bound for Barter Island, where his team of ecologists from the US Minerals Management Service were carrying out an airborne survey of marine mammals. It was a crisp autumn day, with bright sunshine and clear blue skies – perfect for the job at hand.
One of the first observations the team made was polar bears swimming in the Beaufort Sea. Over the roar of the engines, a junior member asked Monnett whether polar bears were strong swimmers. “Oh, they’re pretty good,” replied Monnet. “They would normally restrict themselves to the coastal waters, swimming around 30 kilometres. But since the sea ice has started to recede, we reckon some are now having to swim as far as 200 kilometres to reach their hunting grounds.”
In total, the team counted 40 swimming bears that day, some as far as 100 kilometres offshore. The observations provoked mild surprise, but little else. By the time the team was headed for home, their minds were focused elsewhere: dark clouds had moved in from the west and a fierce wind was causing the pilot a few problems.
The storm forced the team to sit out the next three days. Once it had passed, they set off to finish the survey. What they found made them question the indifference with which they’d observed the bears on the previous outing.
This time, their flight over the open sea revealed the carcasses of four bears. “We think they must have drowned during the storm,” says Monnett. “These animals are strong swimmers. But since the pack-ice has receded, they are being forced to swim farther and farther. If the trend continues, we could well see even more drowning-related deaths.”
Scientists have been warning for more than a decade that the polar bear would be among the first species to suffer from climate change. Now, they say, we’re witnessing the beginning of the end: as well as Monnett’s observations in the Beaufort Sea, WWF has reported cannibalism among bears competing for resources in northeastern Russia, while the Canadian Wildlife Service has observed a 22 per cent decline in the Hudson Bay population.
But it isn’t just polar bears that are feeling the heat. Species all over the world are being pushed to the brink of extinction and beyond. According to new research published this month, the world’s most biodiverse regions are set to lose the largest numbers, with extinction rates as high as 75 per cent. Not only are millions of individual species
in danger, but entire ecosystems could unravel, leaving humans at the mercy of an increasingly extreme and unpredictable climate.
Having woken up to the impact of climate change upon humankind, say conservationists, it’s time we took the threat to the world’s biodiversity seriously. “It’s difficult to underestimate the impact climate change could have,” says Lara Hansen, chief scientist of the WWF Climate Change Program. “Before the end of this century, it will become the single biggest threat to the world’s flora and fauna. It’s a global phenomenon, working on a scale that we’ve never seen from anthropogenic threats. It’s a huge new challenge and requires that we come up with a whole new way to do conservation. But we only have a short space of time, and it’s running out – fast.”
Tip of the iceberg
The UN’s Intergovernmental Panel on Climate Change (IPCC) reported in 2001 that the average global temperature had risen by around 0.6°C during the 20th century in response to an increase in atmospheric CO2. Today, it’s thought the rise in temperature could have reached 0.8°C. The effects of this rise are all around us: Arctic sea-ice is receding; 80 per cent of the world’s mountain glaciers are in retreat; sea levels are rising; and the frequency and intensity of both droughts and floods are increasing.
Without reducing emissions, said the IPCC, CO2 concentration would rise to 550 parts per million (ppm), roughly twice the pre-industrial level, in the next 40–100 years. As a result, temperatures would rise by 1°C–5.8°C. However, a draft IPCC paper leaked to the press earlier this year revealed that computer models suggest they could rise by 11°C.
Until recently, the discussion of climate change has focused on its impact upon humans; little attention has been focused on its effect upon biodiversity. But all over the world, global warming is already having a disastrous effect on a wide range of plants and animals. Two per cent of the world’s amphibian species have already gone extinct; penguin populations have crashed in the Antarctic; in the North Sea, tens of thousands of seabirds have failed to breed because of warming waters; and all over the world, coral reefs are experiencing destructive ‘bleaching’ episodes almost every year.
And it appears that climate change has already caused large-scale extinctions. In January, a paper published in Nature pointed to climate change as the ultimate cause of the extinction of two thirds of the 110 known species of harlequin frog. Changes in temperature and hydrology had apparently led to outbreaks of a deadly fungal disease that had raced through the frogs’ populations, the majority of which were found in pristine highland rainforests of the American tropics.
Now, a new study suggests that these extinctions could be the tip of a rapidly melting iceberg. Published in Conservation Biology in April, the paper assesses the impact of global warming on endemic species in the 25 Conservation International (CI) Biodiversity Hotspots. It suggests that some regions could lose three quarters of their endemics if CO2 concentrations reach 550ppm.
In 2004, scientists predicted that 24 per cent of the world’s species would be driven to extinction if global temperatures rose by 2°C by 2050. The new research concludes that extinctions could be as high as 75 per cent in the Pacific islands of New Caledonia, 70 per cent in southwestern Africa’s succulent Karoo, 66 per cent in southwestern Australia and 58 per cent in Polynesia. As many as 9,400 plant species could disappear from the tropical Andes, 5,750 from the Mediterranean Basin, 3,865 from South Africa’s Cape Floristic Region and 3,395 from the Caribbean.
“This study confirms previous estimates of global extinction risk from climate change,” says Hansen, one of the report’s authors. “It also tells us that, although the polar regions might experience more severe warming, the areas where biodiversity is most concentrated are also vulnerable, particularly those areas where species’ ranges are limited, such as mountains, ends of continents and islands.” This means that, in absolute terms, the greatest losses will be felt in tropical and temperate regions. “This is extremely worrying, considering that many of the species in question are already under threat from deforestation and pollution and other anthropogenic pressures.”
Background extinctions
Palaeontologists will tell you that extinctions are a fact of life, that since the beginning of life on Earth, there has been a constant turnover of plants and animals evolving and dying out. “Few species last more than a few million years,” says Adrian Lister, professor of palaeobiology at University College London. “And climate change has certainly played a significant part in past extinction events – not just the five mass extinctions, but what we call the background extinctions.”
Past episodes of global warming have seen species move towards the poles or upslope in order to maintain a comfortable environment, a phenomenon that’s also being observed today. “The most famous example is the Edith checkspot butterfly, which is shifting northwards from its range in Mexico and California,” says Lee Hannah, senior fellow of climate change biology at CI. “But we’ve also seen it with butterflies in the UK, plants in the Cape and birds in the USA and Europe.” In fact, more than 80 per cent of species that show any kind of distribution change are moving into environments that were previously too cool for them.
This isn’t to say that a blue tit wakes up one day in Kent, feels a bit hot and decides it will be cooler in Yorkshire – these shifts happen at the population level as the boundaries of a species’ range alter. “The distributions of many species are set by occasional extreme climatic events,” says Chris Thomas, professor of conservation biology at York University. “At the northern end of the distribution of the Dartford warbler, for example, we no longer see extended periods of extreme winter cold. So
the bird population has started to spread, and it no longer gets cut back. Meanwhile, at the southern, hot end of the distribution, it may do okay for a while until a new extreme temperature or drought comes along and kills off a bunch of populations.”
Such shifts in range aren’t themselves a problem; however, for many species they simply aren’t an option. “If you’re a wildflower in the Alps and the next suitable patch you might occupy is 1,000 kilometres away in Sweden,” says Brian Huntley, professor of palaeoecology at Durham University, “your chance of survival will be pretty small.” The same goes for the proteas in the Cape region of South Africa, says Hannah. “They’re surviving in a geographic cone at the moment, and as they move towards the South Pole, they’re going to lose range. Eventually, they’ll have nowhere to go.”
However, the limitations on range shifts are only half the problem. There’s a view that climate change was responsible for a major extinction event between 40,000 and 10,000 years ago,
by causing the disappearance of the habitat on which a group of mammals known as the megafauna depended (see Extinction of the megafauna). This theory illustrates an important point for conservationists today: that species respond to climate change individually rather than as communities. “This is perhaps the most difficult aspect for us to deal with,” says Hannah. “If whole communities moved as one, it would be relatively simple to maintain intact ecosystems. It would just be a matter of creating space. But as it stands, no-one can predict exactly how species will react.”
It’s all in the timing
Last year, the BBC teamed up with the Woodland Trust and the UK Phenology Network to launch Springwatch, the largest ever attempt to document the arrival of spring. More than 70,000 members of the public took part, recording the date and location of the first sightings of six key species.
While news presenters may treat these activities as light relief, changes in phenology – the timing of such events as migrations, nesting, breeding, hatching and blossoming – have serious implications for our biodiversity.
Hundreds of phenological studies have backed up what the British public observed. Oak leafing dates, for example, have advanced by around four weeks in the past 50 years, and the sand martin now arrives from Africa between two and three weeks earlier than it did in the 1950s. “Butterflies almost en masse seem to be becoming active much earlier in the year,” says Tim Sparks of the Centre for Hydrology and Ecology at Monks Wood. “And there’s a huge body of evidence that the flowering of plants is very much earlier.”
As with the range shifts, there are fears about the impact of independent phenological responses to climate change. “We’re principally concerned about disruption to the food web,” says Sparks. “If a plant, for example, has advanced considerably in its spring leafing or flowering, then the insects that rely on it have to match that, and the vertebrates that rely on those insects also have to respond.” But many species respond to day length rather than temperature, so the synchronisation of these events can easily break down.
There’s already evidence of such mismatches. A rise of 1°C in the average temperature of the North Sea during the past 25 years has apparently caused many seabirds to fail to breed on
the UK’s eastern coast. “The warming has caused sand-eel stocks to decline from some areas because their plankton food is now blooming at different times,” says Olly Watts, RSPB climate change policy officer. “Sand eels are the main source of food for such seabirds as Arctic terns, guillemots and puffins.”
Migrating animals may be particularly vulnerable to changes in phenology. “Canada geese are arriving in the Arctic before the plants that they feed on have had a chance to grow,” says Hannah. “The geese end up eating the roots, so they are potentially destroying their food source.”
These issues will create strong evolutionary selection pressure, says Hannah. At present, however, no-one knows what’s going to happen. “We don’t know whether we’re facing temporary bottlenecks and these things will be able to adapt and come through it, or whether these changes are moving too rapidly and these relationships will come apart at the seams and the impacts will be permanent.”
This appears to be the key issue surrounding not only phenological disruptions, but all of the impacts of climate change. Although the fossil record shows a constant turnover of species, it also shows that many have been able to adapt to changes in climate. But there’s a danger that today’s human-induced climate change will prove too much.
“We’re seeing a period of very rapid warming taking place on top of what is already a very warm climate,” says Huntley. “The Earth hasn’t experienced anything like this in the past two million years.” Even if some species were able to shift their ranges or adapt, he says, they may not be able to do so fast enough to keep up. “It’s very difficult to say definitively, but the evidence suggests that many species had difficulty coping with past climate change, so its unlikely they will keep up with the changes of the near future.”
Hedging our bets
Many people believe that because the Earth has experienced climate change and extinctions in the past, we shouldn’t worry about the current situation; that organisms will eventually adapt
and life will continue. In other words, don’t worry about climate change: it’s not the end of the world.
True, it probably won’t be the end of the world, says Lister, but this is an incredibly irresponsible view and could well backfire on us. “Humans evolved within a certain ecosystem,” he says. “It’s no coincidence that civilisation developed during the past 10,000 years, when the climate has been consistently warm. As things stand, we’re not only going to cause problems for communities around the world that are vulnerable to rising sea-levels, flooding and droughts. We could end up destroying the very ecosystem in which we evolved.”
Hannah explains: “Biodiversity and the natural world provide humans with a lot of the services we need to get by – clean water, clean air, soil integrity. We have no idea what will happen to these services if ecosystems begin to unravel. It’s quite possible that if temperatures rise above a certain level, whole vegetation structures will shift permanently, leaving us without many of those natural services and resources when we need them most.”
No-one can say, yet, whether there will be such a threshold or what it might be. But several studies predict dramatic changes in the world’s flora and fauna with a rise of around 2°C. “We’re already at around 0.6°C to 0.8°C,” says Hansen. “We’re locked into around 1.4°C because of what we’ve emitted already. So, a 2°C rise really isn’t very far away. It’s abundantly clear that we need to take action very soon to keep ourselves from reaching that point.”
Until now, conservationists have been slow to acknowledge the implications of climate change. “Many people are feeling overwhelmed,” says Hansen. But it looks as if this is starting to change. Most of the larger organisations are now actively addressing climate change. Indeed, at the end of April, CI, the Nature Conservancy and WWF are organising the first climate change training workshop for conservationists, in Washington DC. “The aim is to strengthen the ability of field projects and ecosystems to respond to climate change and promote communication within the conservation community,” says Hansen.
The challenge, she says, is immense. “We’ve traditionally looked to conserve species by protecting space, and we must continue to do that. But now we must think about how the location of that space will change as species shift their ranges. So we need to protect along climatological gradients, which generally will be either altitude or latitude.” And because no-one quite understands how ecosystems work, she continues, conservationists will have to hedge their bets and protect the areas that are more stable. “These so-called climate refugia should have the greatest heterogeneity, so we’re protecting as many parameters as possible.”
Hannah is eager to point out that conservationists must continue to address the traditional threats to biodiversity, such as habitat loss and pollution. “In no way does the threat of climate change mean that we should suddenly run over to the other side of the ship and start doing only climate change work. What it means is that we have a precious few years to address habitat loss before we wind up with this other, more complicated threat on our hands.”
But in the end, says Hansen, there’s a limit to what conservationists can do. “The truth is that we have to mitigate the cause of climate change. We have to reduce greenhouse gas emissions and we have to be serious about that as a global community. Because everything else will just be a Band Aid.”
One of the first observations the team made was polar bears swimming in the Beaufort Sea. Over the roar of the engines, a junior member asked Monnett whether polar bears were strong swimmers. “Oh, they’re pretty good,” replied Monnet. “They would normally restrict themselves to the coastal waters, swimming around 30 kilometres. But since the sea ice has started to recede, we reckon some are now having to swim as far as 200 kilometres to reach their hunting grounds.”
In total, the team counted 40 swimming bears that day, some as far as 100 kilometres offshore. The observations provoked mild surprise, but little else. By the time the team was headed for home, their minds were focused elsewhere: dark clouds had moved in from the west and a fierce wind was causing the pilot a few problems.
The storm forced the team to sit out the next three days. Once it had passed, they set off to finish the survey. What they found made them question the indifference with which they’d observed the bears on the previous outing.
This time, their flight over the open sea revealed the carcasses of four bears. “We think they must have drowned during the storm,” says Monnett. “These animals are strong swimmers. But since the pack-ice has receded, they are being forced to swim farther and farther. If the trend continues, we could well see even more drowning-related deaths.”
Scientists have been warning for more than a decade that the polar bear would be among the first species to suffer from climate change. Now, they say, we’re witnessing the beginning of the end: as well as Monnett’s observations in the Beaufort Sea, WWF has reported cannibalism among bears competing for resources in northeastern Russia, while the Canadian Wildlife Service has observed a 22 per cent decline in the Hudson Bay population.
But it isn’t just polar bears that are feeling the heat. Species all over the world are being pushed to the brink of extinction and beyond. According to new research published this month, the world’s most biodiverse regions are set to lose the largest numbers, with extinction rates as high as 75 per cent. Not only are millions of individual species
in danger, but entire ecosystems could unravel, leaving humans at the mercy of an increasingly extreme and unpredictable climate.
Having woken up to the impact of climate change upon humankind, say conservationists, it’s time we took the threat to the world’s biodiversity seriously. “It’s difficult to underestimate the impact climate change could have,” says Lara Hansen, chief scientist of the WWF Climate Change Program. “Before the end of this century, it will become the single biggest threat to the world’s flora and fauna. It’s a global phenomenon, working on a scale that we’ve never seen from anthropogenic threats. It’s a huge new challenge and requires that we come up with a whole new way to do conservation. But we only have a short space of time, and it’s running out – fast.”
Tip of the iceberg
The UN’s Intergovernmental Panel on Climate Change (IPCC) reported in 2001 that the average global temperature had risen by around 0.6°C during the 20th century in response to an increase in atmospheric CO2. Today, it’s thought the rise in temperature could have reached 0.8°C. The effects of this rise are all around us: Arctic sea-ice is receding; 80 per cent of the world’s mountain glaciers are in retreat; sea levels are rising; and the frequency and intensity of both droughts and floods are increasing.
Without reducing emissions, said the IPCC, CO2 concentration would rise to 550 parts per million (ppm), roughly twice the pre-industrial level, in the next 40–100 years. As a result, temperatures would rise by 1°C–5.8°C. However, a draft IPCC paper leaked to the press earlier this year revealed that computer models suggest they could rise by 11°C.
Until recently, the discussion of climate change has focused on its impact upon humans; little attention has been focused on its effect upon biodiversity. But all over the world, global warming is already having a disastrous effect on a wide range of plants and animals. Two per cent of the world’s amphibian species have already gone extinct; penguin populations have crashed in the Antarctic; in the North Sea, tens of thousands of seabirds have failed to breed because of warming waters; and all over the world, coral reefs are experiencing destructive ‘bleaching’ episodes almost every year.
And it appears that climate change has already caused large-scale extinctions. In January, a paper published in Nature pointed to climate change as the ultimate cause of the extinction of two thirds of the 110 known species of harlequin frog. Changes in temperature and hydrology had apparently led to outbreaks of a deadly fungal disease that had raced through the frogs’ populations, the majority of which were found in pristine highland rainforests of the American tropics.
Now, a new study suggests that these extinctions could be the tip of a rapidly melting iceberg. Published in Conservation Biology in April, the paper assesses the impact of global warming on endemic species in the 25 Conservation International (CI) Biodiversity Hotspots. It suggests that some regions could lose three quarters of their endemics if CO2 concentrations reach 550ppm.
In 2004, scientists predicted that 24 per cent of the world’s species would be driven to extinction if global temperatures rose by 2°C by 2050. The new research concludes that extinctions could be as high as 75 per cent in the Pacific islands of New Caledonia, 70 per cent in southwestern Africa’s succulent Karoo, 66 per cent in southwestern Australia and 58 per cent in Polynesia. As many as 9,400 plant species could disappear from the tropical Andes, 5,750 from the Mediterranean Basin, 3,865 from South Africa’s Cape Floristic Region and 3,395 from the Caribbean.
“This study confirms previous estimates of global extinction risk from climate change,” says Hansen, one of the report’s authors. “It also tells us that, although the polar regions might experience more severe warming, the areas where biodiversity is most concentrated are also vulnerable, particularly those areas where species’ ranges are limited, such as mountains, ends of continents and islands.” This means that, in absolute terms, the greatest losses will be felt in tropical and temperate regions. “This is extremely worrying, considering that many of the species in question are already under threat from deforestation and pollution and other anthropogenic pressures.”
Background extinctions
Palaeontologists will tell you that extinctions are a fact of life, that since the beginning of life on Earth, there has been a constant turnover of plants and animals evolving and dying out. “Few species last more than a few million years,” says Adrian Lister, professor of palaeobiology at University College London. “And climate change has certainly played a significant part in past extinction events – not just the five mass extinctions, but what we call the background extinctions.”
Past episodes of global warming have seen species move towards the poles or upslope in order to maintain a comfortable environment, a phenomenon that’s also being observed today. “The most famous example is the Edith checkspot butterfly, which is shifting northwards from its range in Mexico and California,” says Lee Hannah, senior fellow of climate change biology at CI. “But we’ve also seen it with butterflies in the UK, plants in the Cape and birds in the USA and Europe.” In fact, more than 80 per cent of species that show any kind of distribution change are moving into environments that were previously too cool for them.
This isn’t to say that a blue tit wakes up one day in Kent, feels a bit hot and decides it will be cooler in Yorkshire – these shifts happen at the population level as the boundaries of a species’ range alter. “The distributions of many species are set by occasional extreme climatic events,” says Chris Thomas, professor of conservation biology at York University. “At the northern end of the distribution of the Dartford warbler, for example, we no longer see extended periods of extreme winter cold. So
the bird population has started to spread, and it no longer gets cut back. Meanwhile, at the southern, hot end of the distribution, it may do okay for a while until a new extreme temperature or drought comes along and kills off a bunch of populations.”
Such shifts in range aren’t themselves a problem; however, for many species they simply aren’t an option. “If you’re a wildflower in the Alps and the next suitable patch you might occupy is 1,000 kilometres away in Sweden,” says Brian Huntley, professor of palaeoecology at Durham University, “your chance of survival will be pretty small.” The same goes for the proteas in the Cape region of South Africa, says Hannah. “They’re surviving in a geographic cone at the moment, and as they move towards the South Pole, they’re going to lose range. Eventually, they’ll have nowhere to go.”
However, the limitations on range shifts are only half the problem. There’s a view that climate change was responsible for a major extinction event between 40,000 and 10,000 years ago,
by causing the disappearance of the habitat on which a group of mammals known as the megafauna depended (see Extinction of the megafauna). This theory illustrates an important point for conservationists today: that species respond to climate change individually rather than as communities. “This is perhaps the most difficult aspect for us to deal with,” says Hannah. “If whole communities moved as one, it would be relatively simple to maintain intact ecosystems. It would just be a matter of creating space. But as it stands, no-one can predict exactly how species will react.”
It’s all in the timing
Last year, the BBC teamed up with the Woodland Trust and the UK Phenology Network to launch Springwatch, the largest ever attempt to document the arrival of spring. More than 70,000 members of the public took part, recording the date and location of the first sightings of six key species.
While news presenters may treat these activities as light relief, changes in phenology – the timing of such events as migrations, nesting, breeding, hatching and blossoming – have serious implications for our biodiversity.
Hundreds of phenological studies have backed up what the British public observed. Oak leafing dates, for example, have advanced by around four weeks in the past 50 years, and the sand martin now arrives from Africa between two and three weeks earlier than it did in the 1950s. “Butterflies almost en masse seem to be becoming active much earlier in the year,” says Tim Sparks of the Centre for Hydrology and Ecology at Monks Wood. “And there’s a huge body of evidence that the flowering of plants is very much earlier.”
As with the range shifts, there are fears about the impact of independent phenological responses to climate change. “We’re principally concerned about disruption to the food web,” says Sparks. “If a plant, for example, has advanced considerably in its spring leafing or flowering, then the insects that rely on it have to match that, and the vertebrates that rely on those insects also have to respond.” But many species respond to day length rather than temperature, so the synchronisation of these events can easily break down.
There’s already evidence of such mismatches. A rise of 1°C in the average temperature of the North Sea during the past 25 years has apparently caused many seabirds to fail to breed on
the UK’s eastern coast. “The warming has caused sand-eel stocks to decline from some areas because their plankton food is now blooming at different times,” says Olly Watts, RSPB climate change policy officer. “Sand eels are the main source of food for such seabirds as Arctic terns, guillemots and puffins.”
Migrating animals may be particularly vulnerable to changes in phenology. “Canada geese are arriving in the Arctic before the plants that they feed on have had a chance to grow,” says Hannah. “The geese end up eating the roots, so they are potentially destroying their food source.”
These issues will create strong evolutionary selection pressure, says Hannah. At present, however, no-one knows what’s going to happen. “We don’t know whether we’re facing temporary bottlenecks and these things will be able to adapt and come through it, or whether these changes are moving too rapidly and these relationships will come apart at the seams and the impacts will be permanent.”
This appears to be the key issue surrounding not only phenological disruptions, but all of the impacts of climate change. Although the fossil record shows a constant turnover of species, it also shows that many have been able to adapt to changes in climate. But there’s a danger that today’s human-induced climate change will prove too much.
“We’re seeing a period of very rapid warming taking place on top of what is already a very warm climate,” says Huntley. “The Earth hasn’t experienced anything like this in the past two million years.” Even if some species were able to shift their ranges or adapt, he says, they may not be able to do so fast enough to keep up. “It’s very difficult to say definitively, but the evidence suggests that many species had difficulty coping with past climate change, so its unlikely they will keep up with the changes of the near future.”
Hedging our bets
Many people believe that because the Earth has experienced climate change and extinctions in the past, we shouldn’t worry about the current situation; that organisms will eventually adapt
and life will continue. In other words, don’t worry about climate change: it’s not the end of the world.
True, it probably won’t be the end of the world, says Lister, but this is an incredibly irresponsible view and could well backfire on us. “Humans evolved within a certain ecosystem,” he says. “It’s no coincidence that civilisation developed during the past 10,000 years, when the climate has been consistently warm. As things stand, we’re not only going to cause problems for communities around the world that are vulnerable to rising sea-levels, flooding and droughts. We could end up destroying the very ecosystem in which we evolved.”
Hannah explains: “Biodiversity and the natural world provide humans with a lot of the services we need to get by – clean water, clean air, soil integrity. We have no idea what will happen to these services if ecosystems begin to unravel. It’s quite possible that if temperatures rise above a certain level, whole vegetation structures will shift permanently, leaving us without many of those natural services and resources when we need them most.”
No-one can say, yet, whether there will be such a threshold or what it might be. But several studies predict dramatic changes in the world’s flora and fauna with a rise of around 2°C. “We’re already at around 0.6°C to 0.8°C,” says Hansen. “We’re locked into around 1.4°C because of what we’ve emitted already. So, a 2°C rise really isn’t very far away. It’s abundantly clear that we need to take action very soon to keep ourselves from reaching that point.”
Until now, conservationists have been slow to acknowledge the implications of climate change. “Many people are feeling overwhelmed,” says Hansen. But it looks as if this is starting to change. Most of the larger organisations are now actively addressing climate change. Indeed, at the end of April, CI, the Nature Conservancy and WWF are organising the first climate change training workshop for conservationists, in Washington DC. “The aim is to strengthen the ability of field projects and ecosystems to respond to climate change and promote communication within the conservation community,” says Hansen.
The challenge, she says, is immense. “We’ve traditionally looked to conserve species by protecting space, and we must continue to do that. But now we must think about how the location of that space will change as species shift their ranges. So we need to protect along climatological gradients, which generally will be either altitude or latitude.” And because no-one quite understands how ecosystems work, she continues, conservationists will have to hedge their bets and protect the areas that are more stable. “These so-called climate refugia should have the greatest heterogeneity, so we’re protecting as many parameters as possible.”
Hannah is eager to point out that conservationists must continue to address the traditional threats to biodiversity, such as habitat loss and pollution. “In no way does the threat of climate change mean that we should suddenly run over to the other side of the ship and start doing only climate change work. What it means is that we have a precious few years to address habitat loss before we wind up with this other, more complicated threat on our hands.”
But in the end, says Hansen, there’s a limit to what conservationists can do. “The truth is that we have to mitigate the cause of climate change. We have to reduce greenhouse gas emissions and we have to be serious about that as a global community. Because everything else will just be a Band Aid.”
|
| |
 | |
2. Bangkok's ghost towers 3. UK population to exceed 100 million 4. Wild west a dusty place 5. NEW! Free Geographical wallpapers | |
 FREE DIGITAL ISSUE | |
 | |
