'Global warming century's biggest challenge'

"The global map as we know it has not changed in the last 12,000 years. This roughly corresponds to the origin and development of our own civilisation. This is the reason why we have gone ahead and built many of our cities on coastlines. But with global warming and the rising of sea water levels the global map as we know it is going to change," stressed David King, chief scientific advisor to the British government.

He was addressing a select audience of Bangalore's 'intellect' at the National Institute of Advanced Studies, Indian Institute of Sciences here on Monday, discussing 'Global Warming and Climate Change: The Imperative for Change', one of the subjects chosen by the UK to focus on during its G8 presidency.

Tracing the evolution of the understanding of the greenhouse effect from 1827, King pointed out the link between increased carbon dioxide concentrations in the atmosphere and changes in climate.

"Investigations in the ice cores as well as sea sediments reveal that the earth was warmer during the periods where carbon dioxide was present in larger quantities," he said.

"If you see the concentration of the gas in the atmosphere, going back 50,000 years, it was around 200 parts per million, which corresponds to the glacial age. This slowly increased to 260 parts per million, around 12,000 years ago."

Therefore, "our civilization is in one of the warmer periods of the earth. But then, we had the industrial revolution and increasing population resulting in more fossil fuel consumption. For the first time in history, we managed to take carbon and release it (by burning it) into the atmosphere, thereby transforming it. The carbon dioxide concentration now is around 379 parts per million and it is increasing at 2 parts per million every year," added King.

Calling global warming 'the biggest challenge faced by the globe this century', King went on to elaborate on how the increased temperatures was melting ice in different parts of the world and adding to sea water.

"Some of the changes that scientists have observed with the increasing temperature is a change in the earth's ice and cloud cover, the weakening of the 'gulf stream's' warming effect due to dilution and a switching of the Indian monsoon. Considering how the Indian economy is dependent on its monsoon, one can understand the effect that warming can have globally," emphasised King.

King emphasised that several thing would have to work together to prevent the drastic changes that would result from further warming.

Diversifying supplies of energy, improving energy efficiency and use of renewables could aid in cutting down on emission. Stopping emission growth now also commits us to a period of global warming and therefore, it's the long term effects that we have to focus on while reducing emissions, he said.