VICTORIA, British Columbia, July 29 (UPI) -- A runaway greenhouse effect, where the Earth could get too hot to support life, is easier to initiate than previously believed, a Canadian scientist says.
New calculations that suggest this so-called runaway greenhouse could cause oceans to entirely evaporate, said Colin Goldblatt, a professor of Earth system evolution at the University of Victoria in British Columbia.
"We could go into the runaway greenhouse today if we could get the planet hot enough to get enough water vapor into the atmosphere," Goldblatt told NBC News.
In the greenhouse effect, increasing amounts of water vapor, carbon dioxide and other gases in the atmosphere absorb increasing amounts of solar energy reflected by the Earth, while only a fixed amount can escape from the atmosphere to space.
"If we absorb more solar radiation than that maximum we can emit, then all that can happen is the Earth is going to warm," Goldblatt said. "It just can't keep itself in energy balance anymore."
However, he said, even burning all the planet's fossil fuels such as oil and coal is "very unlikely" to trigger such uncontrollable warming.
"Our estimate is that it would take 30,000 parts per million of carbon dioxide in the atmosphere to make it warm enough to trigger this runaway greenhouse," Goldblatt said, noting current CO2 levels are at 400 parts per million.
Reaching 30,000 parts per million "really seems quite unlikely," Goldblatt said, although a slim chance of a runaway greenhouse due to human activity stems from the inherent uncertainty in the calculations.
Still, Goldblatt and his researcher colleagues said, "anthropogenic emissions are probably insufficient" to trigger a runaway greenhouse.