Hannah Devlin, Times Online 6 Nov 09;
Alarming predictions that climate change will lead to the extinction of hundreds of species may be exaggerated, according to Oxford scientists.
They say that many biodiversity forecasts have not taken into account the complexities of the landscape and frequently underestimate the ability of plants and animals to adapt to changes in their environment.
“The evidence of climate change-driven extinctions have really been overplayed. We’re going to lose five or six species due to climate change, not hundreds,” said Professor Kathy Willis, a long-term ecologist at the University of Oxford and lead author of the article.
Professor Willis warned that alarmist reports were leading to ill-founded biodiversity policies in government and some major conservation groups. She said that climate change has become a “buzz word” that is taking priority while, in practice, changes in human use of land have a greater impact on the survival of species. “I’m certainly not a climate change denier, far from it, but we have to have sound policies for managing our ecosystems,” she said.
The International Union for the Conservation of Nature backed the article, saying that climate change is “far from the number-one threat” to the survival of most species. “There are so many other immediate threats that, by the time climate change really kicks in, many species will not exist any more,” said Jean Christophe Vie, deputy head of the IUCN species program, which is responsible for compiling the international Redlist of endangered species.
He listed hunting, overfishing, and destruction of habitat by humans as more critical for the majority of species.
However, the Royal Society for the Protection of Birds disagreed, saying that climate change was the single biggest threat to biodiversity on the planet. “There’s an absolutely undeniable affect that’s happening now,” said John Clare, an RSPB spokesman. “There have been huge declines in British sea birds.”
The article, published today in the journal Science, reviews recent research on climate change and biodiversity, arguing that many simulations are not sufficiently detailed to give accurate predictions.
In particular, the landscape is often described at very low resolution, not taking into account finer variations in vegetation and altitude that are vital predictors for biodiversity.
In one analysis of the likelihood of survival of alpine plant species in the Swiss Alps, the landscape was depicted with a 16km by 16km (10 miles by 10 miles) grid scale. This model predicted that all suitable habitats for alpine plants would have disappeared by the end of the century. When the simulation was repeated with a 25m by 25m (82ft by 82ft) scale, the model predicted that areas of suitable habitat would remain for all plant species.
The article suggests that migration to new regions and changes in living patterns of species would take place but that actual extinction would be rare.
Other studies comparing predictions of extinction rates with actual extinction rates have come to similar conclusions. According to a high-profile paper published in the journal Nature in 2004, up to 35 per cent of bird species would be extinct by 2050 due to changes in climate. To be on track to meet this figure, Professor Keith Bennett, head of geography at Queen’s University Belfast, calculated that about 36 species would have to have become extinct each year between 2004 and 2008. In reality, three species of bird became extinct.
He said that many species are far more versatile than some prediction models give them credit for. “If it gets a couple of degrees warmer than they’re comfortable with, they don’t just die, they move,” he said.
Can Biodiversity Persist In The Face Of Climate Change?
ScienceDaily 6 Nov 09;
Predictions made over the last decade about the impacts of climate change on biodiversity may be exaggerated, according to a paper published in the journal Science.
Oxford University researchers, Professor Kathy Willis and Dr Shonil Bhagwat, argue that predicting the fate of biodiversity in the face of climate change is 'fraught with caveats and complexities'.
They say that several larger-scale models are failing to take into account local, more detailed variations and that models often underestimate the full capacity of plants and animals to adapt to a changing climate.
The researchers' view is that these factors 'seriously alter the model predictions'. They suggest that 'we should expect to see species turnover, migrations, and novel communities, but not necessarily the levels of extinction previously predicted'.
Their synthesis of research highlights the contradictions in previous studies about the likely survival rates of alpine plants in the Swiss Alps, European butterfly populations and the South American tropical rainforests.
'These studies highlight the level of complexity that we are faced with in trying to model and predict the possible consequences of future climate change on biodiversity,' the paper says. The researchers say the mixed picture that is emerging from previous studies also emphasises a high level of persistence in many communities.
Although over three quarters of the earth's deserts, grasslands, forests and tundra have changed because of human activity, the researchers say that even in this fragmented landscape species are surviving better than was previously predicted. The paper cites more recent studies and concludes that even in altered landscapes 'all is not lost for biodiversity'.
The researchers point to a study into 785 animal species across six continents, which suggests the most important factor for occupancy is the quality of the animals' immediate environment rather than whether their habitat is shrinking. Their paper also highlights a study of forest butterflies in West Africa, which found that despite an 87 per cent reduction in forest cover, 97 per cent of species are still present.
Professor Kathy Willis, from the School for Geography and the Environment, expresses some caution about the apparent ability of species to survive in a more fragmented habitat. She said: 'Presence or absence does not take into account lag effects of declining populations. Therefore, a more worrying interpretation is that the full effects of fragmentation will only be seen in future years.'
The paper also highlights a serious issue for future conservationists, arguing that the definition of 'natural' is changing fast.
Dr Shonil Bhagwat, from the School of Geography and the Environment, said: 'Although every measure should be put in place to reduce the further fragmentation of reserves, we cannot turn back the clock. We need to determine what represents a "good" intervention to preserve animal habitats in the countryside and in towns and cities. Furthermore, we will increasingly see new ecosystems emerging as a result of climate changes and so what is "natural" is going to require a whole new definition.'
Adapted from materials provided by University of Oxford.
Studies 'overstate species risks'
Mark Kinver, BBC News 6 Nov 09;
Some large-scale computer simulations may be overestimating the impact of climate change on biodiversity in some regions, researchers have suggested.
They said models that analyse vast areas often failed to take into account local variations, such as topography and microclimates.
Local-scale simulations, which did include these factors, often delivered a more optimistic outlook, they added.
The findings have been published in the journal, Science.
One of the studies cited in the paper looked at the fate of plant species in the Swiss Alps.
"A coarse European-scale model (with 16km by 16km grid cells) predicted a loss of all suitable habitats during the 21st Century," the researchers wrote.
"Whereas a model run using local-scale data (25m by 25m grid cells) predicted (the) persistence of suitable habitats for up to 100% of plant species."
Micro v macro
Co-author Shonil Bhagwat, a senior research fellow at the University of Oxford, UK, said when vegetation was looked at on a smaller scale, scientists saw a different picture.
"For example, smaller plots give data on microclimatic variations, whereas large-scale models predict (uniform) changes throughout the landscape."
Advances in computing power meant that more large-scale datasets were being made available to scientists, Dr Bhagwat explained.
"There is more interest in predicting widespread, large-scale effects," she told BBC News, "that is why coarser-scale models are normally used.
"However, the changes in communities of vegetation occur at a much smaller scale."
In the paper, Dr Bhagwat and co-author Professor Kathy Willis, wrote: "These studies highlight the complexities that we are faced with trying to model and predict the possible consequences of future climate change on biodiversity."
The researchers called for more micro-scale studies to be carried out that complement the overall picture presented by larger models.
However, they added that the overall picture for biodiversity loss was still bleak, especially once the rate of habitat loss and fragmentation was taken into account.
"Predicting the fate of biodiversity in response to climate change combined with habitat fragmentation is a serious undertaking fraught with caveats and complexities," they observed.
For example, Dr Bhagwat explained, the current system of having fixed nature reserves may need to be reconsidered.
"We have 12% of the Earth's land surface covered in protected areas, but climate change is likely to push species out of their home ranges and out of reserves," she added.
"So we need to look beyond reserves and create the conditions that allow the migration of species."
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