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"More Disasters" For Warmer World    [

    Forecast Puts Earth's Future Under a Cloud
    By Alok Jha
    The Guardian UK

    Tuesday 15 August 2006

3C increase would bring fires, floods and famine. Climate prediction most comprehensive so far.

    More than half of the world's major forests will be lost if global temperatures rise by an average of 3C or more by the end of the century, it was claimed yesterday. The prediction comes from the most comprehensive analysis yet of the potential effects of human-made global warming.

    Extreme floods, forest fires and droughts will also become more common over the next 200 years as global temperatures rise owing to climate change, according to Marko Scholze of Bristol University. Dr Scholze took 52 simulations of the world's climate over the next century, based on 16 different climate models, grouping the results according to varying amounts of global warming they predicted by 2100: less than 2C on average, 2C-3C and more than 3C. He then used the simulations to work out how the world's plants would be affected over the next few hundred years. The results were published yesterday in the Proceedings of the National Academy of Sciences.

    Alan O'Neill, science director for the National Centre for Earth Observation, said: "Some work in this area has been done before looking at the meteorological forecasts for climate change and feeding those into vegetation models ... this is a much more comprehensive study."

    He added that Dr Scholze's results would give climate scientists the most accurate scientific projection yet of the future effects of global warming.

    Dr Scholze said the effects of a 2C category were inevitable. This is the temperature rise that will happen, on average, even if the world immediately stopped emitting greenhouse gases. This scenario predicts that Europe, Asia, Canada, central America and Amazonia could lose up to 30% of its forests.

    A rise of 2C-3C will mean less fresh water available in parts of west Africa, central America, southern Europe and the eastern US, raising the probability of drought in these areas. In contrast, the tropical parts of Africa and South America will be at greater risk of flooding as trees are lost. Dr Scholze says a global temperature rise of more than 3C will mean even less fresh water. Loss of forest in Amazonia and Europe, Asia, Canada and central America could reach 60%.

    A 3C warming could also present a yet more dangerous scenario where the temperatures induce plants to become net producers of carbon dioxide. "As temperatures go up, plants like it better and they start to grow more vigorously and start to take up more carbon dioxide from the air," Dr O'Neill said. "But there comes a point where the take-up is saturated for a given vegetation cover, then the ecosystem starts to respire more than it's taking up."

    Dr Scholze's work shows that this so-called "tipping point" could arrive by the middle of this century. His scenarios echo research from the UK's Hadley Centre, a world leader in climate change modelling. In a report published last year called Avoiding Dangerous Climate Change, scientists at the centre predicted that a 3C rise in average temperatures would cause a worldwide drop in cereal crops of between 20m and 400m tonnes, put 400 million more people at risk of hunger, and put up to 3 billion people at risk of flooding and without access to fresh water supplies.

    In May, David King, the government's chief scientific adviser, warned that the world's temperature would rise by 3C, causing catastrophic damage around the world, unless governments took urgent action to reduce carbon emissions.

    Dr Scholze said his work could help to define the concept of dangerous climate change for policymakers. "Dangerous is very objective. We tried to define a dangerous level and see what the risks are," he said. In his definition, climate change becomes dangerous when an event - such as extreme flooding or heatwaves - that only happened once every 100 years becomes one that happens every 10 years.

    He added that a rise of 3C was not inevitable. "We can't just do what we do at the moment, what we call business as usual. We have a few decades - we have to do something before 2040."

    Burning Issue

    At the rate we are burning fossil fuels, global temperatures could easily increase by more than the 3C rise that Marko Scholze's research warns could increase flooding, forest fires and droughts. A 2001 report by the Intergovernmental Panel on Climate Change said an increase of between 1.4 and 5.8C by 2100 would be caused if current carbon emissions continue.

    Global sea levels would rise by between 0.09 and 0.88 metres as a result. Scientists at the UK Climate Impacts Programme predict that a 3C rise or above would reduce rain on the south coast to half of current levels, by more than 40% across the rest of England and 30% in Scotland.

    Sea levels could be 70cm higher in the south and there would be a 17-fold increase in flooding on the east coast. London could face a £25bn clean-up bill after a storm surge that would overwhelm the Thames barrier.

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    "More Disasters" For Warmer World
    BBC News

    Monday 14 August 2006

Rising temperatures will increase the risk of forest fires, droughts and flooding over the next two centuries, UK climate scientists have warned.

    Even if harmful emissions were cut now, many parts of the world would face a greater risk of natural disasters, a team from Bristol University said.

    The projections are based on data from more than 50 climate models looking at the impact of greenhouse gas emissions.

    The study appears in the Proceedings of the National Academy of Sciences.

    The researchers gathered results from 52 computer simulations to calculate the risks from climate-induced changes to the world's key ecosystems.

    They then grouped the results according to the amount of global warming: less than 2C (3.6F); 2-3C (3.6F-5.4F); and more than 3C (5.4F).

    For each of the temperature ranges, the team assessed the probability of changes in forest cover, the frequency of wildfires and changes to freshwater supplies over the next 200 years.

    "Dangerous Climate Change"

    Marko Scholze, from the University of Bristol's Department of Earth Sciences, and the paper's lead author, said the findings revealed a direct link between rises in global temperature and damage to ecosystems.

    "We show the steeply increasing risks, and increasingly large areas affected, associated with higher warming levels," he said.

    "The United Nations says we should limit greenhouse gas emissions so we do not have dangerous climate change. So the question is 'what is dangerous climate change?'.

    "In this paper we define the level we think is dangerous and see how likely it will come true," Dr Scholze told BBC News.

    Richard Betts, manager of Climate Impacts at the Met Office's Hadley Centre, welcomed the findings.

    "This makes an important new contribution to the debate on the effects of climate change," he said.

    "We already knew that we cannot rely on just one model, as different models give different answers.

    "This work helps us go beyond that vague statement, as it shows how much the models agree on particular levels of impact and how much they disagree."

    He said the research was an important first step towards quantifying the risks of damaging impacts associated with particular levels of global warming.

    The findings showed areas that would experience the worst forest loss would include Eurasia, eastern China, Canada and the Amazon.

    Areas of western Africa, southern Europe and eastern US states were at most risk from dwindling freshwater supplies and droughts as a result of rising temperatures.

    The data also showed that any temperature increase of more than 3C (5.4F) could result in land "carbon sinks" releasing their stored carbon into the atmosphere, exacerbating the problem of global warming.

    Dr Scholze hoped the collated data would answer some of the concerns among more sceptical members of the scientific community who questioned the accuracy of climatic modelling.

    "That is exactly why we did this study," he said. "We used as many models as we could and did not rely on any one study.

    "We looked at 52 simulations and the probabilities of dangerous climate change these models showed."

    Dr Betts agreed: "Of course it is risky to make these projections when models are continuously being changed, but we do have to make decisions on climate change now so if we wait for the perfect model we will be too late.

    "The models give the best encapsulation of current understanding of the climate system, and are the only way of assessing physically plausible futures."

    Dr Scholze said he hoped the findings would be used in debates on dangerous climate change and the measures needed to avoid it.