Some scientists believe it's already too late to stop the dangerous effects of climate change.But some say there is one possible way to at least slow the damage. CCTV correspondent Jeff Napshin has more on the controversial concept of geo-engineering.

It happens every time there's a major volcanic erruption.

Clouds of ash enter the atmosphere blocking the sun and lowering the temperature. That gave climate scientists an idea that's led to the development of geo-engineering: a man-made effort to modfiy the climate in order to fight global warming.

Mike Maccracken, Climate Institute, said, "It's something that's gonna be necessary.If we don't do it the damage will be so severe that we just won't wanna tolerate it."

Mike MacCracken is chief scientist at the Climate Institute in Washington.

He says geo-engineering is intended to slow the effects of climate change--which many believe is raising global temperatures and sea levels while changing weather patterns.

But some experts say you shouldn't play god with Mother Nature.

Ning Zeng, Professor of University of Maryland, said, "I think some of them could be potentially dangerous."

Professor Ning Zeng is an atmospheric scientist at the University of Maryland.

He says geo-engineering is just begninning to be studied.

Professor Zeng supports well known efforts like re-forrestation -- which adds trees in an effort to remove carbon dioxide from the atmosphere.

But he believes other ideas are potentially dangerous.

For example, some scientists are foccussed on reducing solar radiation: from intentionally brightening clouds to dropping sulphate particles into the air.

He said, "You inject them into the atmosphere for a longer life so they can stay there and mimic the process of a volcanic erruption."

The idea is to gradually lower the earth's temperature. But problems range from controlling the level of sun blockage to the impact on precipitation patterns which could result in a drought.

Jeff Napshin said, "That's why the House Committee on Science and Technology recently released a report that studied the issue. And the United Nations has taken a position opposing geo-engineering because of unintended consequences."

But scientists like Mike MacCracken say we'll have to find a way to fight global warming because today's high level of greenhouse gases will remain in the atmosphere for centuries to come.

He said, "You don't wanna do this kind of thing and modify the environment but we've gotten to a situation where there's no choice."

And perhaps that, more than anything else, is what's truly frightening.