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.
;shut terstock ir a j/REUTERS
16 www.geographical.co.uk december 2010