C l imatewatch

ABOVE: a survivor of Cyclone Aila takes part in a demonstration on the first anniversary of the cyclone in the capital of Bangladesh, Dhaka, in May

Climate change will hit Asia hardest

Asia is likely to be the continent worst affected by climate change, according to a new global ranking of the vulnerability of 170 countries to the impacts of climate change over the next 30 years.

British risk-analysis company Maplecroft created the index using data from more than 40 studies to evaluate 42 social, economic and environmental factors, including a nation’s exposure to climate-related disasters, its population density and dependence on agriculture. According to Maplecroft, the countries most at risk are characterised by high levels of poverty, dense populations, exposure to climate-related events and a reliance on flood and drought prone agricultural land.

ixteen countries were found to be at ‘extreme risk’, ten of them from Asia. Bangladesh was rated the country most at risk due to extreme levels of poverty, a high dependency on agriculture and the lowest capacity of all countries to adapt to changes in the climate. The countries at lowest risk were mostly in Scandinavia, although Ireland also performed well.

‘There is growing evidence that climate change is increasing the intensity and frequency of climatic events,’ said Anna Moss, an environmental analyst at Maplecroft. ‘Very minor changes to temperature can have major impacts on the human environment, including changes to water availability and crop productivity, the loss of land due to sea-level rise and the spread of disease.’

n Carbon dioxide levels act as planetary thermostat: The Earth’s temperature ultimately depends on the amount of carbon dioxide in the atmosphere, according to a new study by scientists at NASA’s Goddard Institute for Space Studies.

ater vapour and cloud are the major contributors to the greenhouse effect, accounting for three quarters of the absorption of outgoing infrared radiation. CO2 accounts for around 20 per cent of the effect, while minor gases and aerosols make up the remainder. However, according to the study, water vapour and cloud are unable to sustain the effect on their own.

he experiment carried out by the scientists was simple in both design and concept. They simply took an existing climate model and dropped the levels of so-called non-condensing greenhouse gases – such as CO2, methane and nitrous oxide – down to zero. They then ran the model forwards in time to see what effect this had.

hey found that without the sustaining support of these gases, the greenhouse effect rapidly collapsed as water vapour precipitated out of the atmosphere, and the Earth became icebound. The results clearly demonstrated that the water vapour acts as a feedback process that needs the climate-forcing effect of CO2 and other greenhouse gases to sustain the greenhouse effect.

‘The bottom line is that atmospheric CO2 acts as a thermostat in regulating the temperature of the Earth,’ said Andrew Lacis, one the study’s authors.

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16 www.geographical.co.uk december 2010 C l imatewatch shut terstock n Landslide risk on the rise: Melting glaciers are putting hundreds of thousands of people at risk from catastrophic landslides, according to a US scientist.

leven thousand years ago, about a third of the cone of the Planchón-Peteroa volcano in Chile collapsed, causing ten billion cubic metres of rock to slide down and cover an area of 370 square kilometres. According to Daniel Tormey, of ENTRIX, an environmental consultancy based in Los Angeles, previous studies have ruled out heavy rainfall as a cause of the landslide, so glacial melting must have been to blame.

ormey’s research on the collapse of PlanchónPeteroa, chosen because altitude and latitude make it likely to feel the effects of climate change before others, points to the likelihood of similar collapses taking place on other glaciated volcanoes around the world as global warming intensifies. Glacial melting removes the glue that holds steep mountain slopes together, and Tormey fears that the resulting landslides have the potential to cause significant loss of life. ‘There are far more human settlements and activities near the slopes of glaciated active volcanoes today than there were 10,000 years ago, so the effects could be catastrophic,’ he said.

on-glaciated volcanoes may also pose a significant risk if climate change increases rainfall, according to ongoing studies being carried out by Bill McGuire of University College London and Rachel Lowe of the University of Exeter. ‘We have found that 39 cities with populations greater than 100,000 are situated within 100 kilometres of a volcano that has collapsed in the past and which may, therefore, be capable of collapsing in the future,’ McGuire told New Scientist.

n Increasing amounts of fresh water flowing into oceans: More frequent and extreme storms linked to global warming are causing the amount of fresh water flowing into the oceans to increase significantly, according to a new study published in the Proceedings of the National Academy of Sciences.

he study used satellite records of sea-level rise, precipitation and evaporation to create a 13-year monthly record of water volume flowing from the continents into the oceans. The results showed that in total, 18 per cent more water fed into the oceans from rivers and melting polar ice sheets in 2006 than in 1994.

According to the authors, the evaporation and precipitation cycle is accelerating because of rising global temperatures. Higher temperatures lead to more rapid evaporation, which leads to thicker clouds and more powerful storms over land. ‘What we’re seeing is exactly what the Intergovernmental Panel on Climate Change predicted – that precipitation is increasing in the tropics and the Arctic Circle, with heavier, more punishing storms. Meanwhile, hundreds of millions of people live in semiarid regions, and those are drying up,’ said one of the study’s authors, Jay Famiglietti of the University of California, Irvine.

he researchers cautioned that the time frame covered by the study was relatively short, and that further study is required.

Drought set to become commonplace

Much of the globe will experience severe and prolonged drought in coming decades as a result of warming temperatures, according to a study by a US National Center for Atmospheric Research scientist.

Using results from the 22 computer models used by the Intergovernmental Panel on Climate Change and a comprehensive index of drought conditions, as well as analyses of previously published studies, Aiguo Dai created regional climate projections for the entire globe. The results showed that most of the Western Hemisphere, along with parts of Eurasia, Africa and Australia, may suffer extreme drought this century, while higher-latitude regions from Alaska to Scandinavia are likely to become more moist. Overall, the globe’s land areas are likely to be drier. ‘The increased wetness over the northern, sparsely populated high latitudes can’t match the drying over the more densely populated temperate and tropical areas,’ Dai said.

Dai cautioned that the findings were based on the best current projections for greenhouse gas emissions; the actual outcomes will depend on a number of factors, including both actual emissions and natural climate cycles such as El Niño. However, he warned that ‘if the projections in this study come even close to being realised, the consequences for society will be enormous’.

In brief

CARIBBEAN Unusually high water temperatures in the western Caribbean have caused extensive coral bleaching, according to Smithsonian Tropical Research Institute scientists. Temperatures as high as 32°C were recorded around Isla Colon in Panama’s Bocas del Toro province in July; normal temperatures at this time of year are closer to 28°C.

ARCTIC The latest Arctic Report Card, an annual assessment of Arctic conditions produced by the US National Oceanic and Atmospheric Administration, has pointed to continued unprecedented warming in the region. Among the 2010 highlights are record-setting temperatures in Greenland and the lowest snow-cover duration since records began in 1966.

UK Growth in carbon emissions from consumption has outstripped savings made through improvements in the efficiency of global supply chains, according to a recently published report from the Department for Environment, Food and Rural Affairs. The analysis of global production showed that although the move towards a service economy has helped to decrease emissions in the UK, increased consumption of foreign goods has led to an overall increase in emissions.

ARCTIC A group of US and Canadian scientists has warned that the opening up of new shipping lanes across the Arctic due to ice loss from warmer temperatures could accelerate warming in the region. Although distance savings would lower emissions by cutting fuel use, the production of soot particles could increase warming by as much as 78 per cent by 2030, according to the scientists.

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