A leading climate scientist has said that the global warming has already reached "tipping points", and that present levels of greenhouse gases will further worsen the climate on Earth.
James Hansen, a climatologist at the NASA Goddard Institute for Space Studies in New York City, issued this warning during a presentation at the American Geophysical Union fall meeting in San Francisco.
He recommended curbing the use of fossil fuels such as oil and coal to avoid any further climatic damage. He said that such fuels were responsible for most of human-caused emissions of carbon dioxide (CO2), which are widely believed to be driving global warming.
Hansen revealed that the current level of CO2 in the atmosphere was enough to cause the Arctic sea ice cover and massive ice sheets such as in Greenland to eventually melt away.
He further said that uninterrupted changes would cause climatic zones like the tropics and temperate regions to continue to shift, and the oceans to become more acidic, endangering much marine life.
"I think in most of these cases, we have already reached the tipping point," the National Geographic quoted him as saying.
Hansen, however, said that mending the way people use energy might help prevent such damages.
"In my opinion, we have not passed the point of no return, so that it's still possible to avoid the impacts. The problem is that it's just been taken as a God-given fact that we're going to burn all of these fossil fuels and let the CO2 in the atmosphere," he said.
"You just can't do that if you're going to keep this planet resembling the one that we've had for the last 10,000 years," he added.
According to Hansen, the oceans and land currently absorb roughly half of the CO2 people emit each year. If humans stopped emitting CO2 through fossil fuel use, he said, the gas would continue to be soaked up and levels in the atmosphere would drop.
"We have to figure out how to live without fossil fuels someday. Why not sooner?" he said.