Worrying that humankind is destroying the Earth with global warming? Relax, says a University of Victoria assistant professor. Though overheating might eventually spell the planet's doom, it will take at least 500 million years to happen.

That's the prediction of Colin Goldblatt, a professor at the University of Victoria's School of Earth and Ocean Sciences. He believes a "runaway greenhouse" effect will be the true end to life on Earth.

Goldblatt's theory hinges on what scientists know about the atmosphere and what has occurred on other planets.

Goldblatt says the sun is slowly growing brighter and is now about 30 per cent brighter than it was when the Earth was formed.

As the sun brightens, the Earth's atmosphere will become thick, helping to trap the infrared radiation trying to escape from the planet's surface. Only the top of the atmosphere will be able to radiate heat out into space, while the rest of the Earth's surface will heat up.

The heat would eventually reach about 1,100 degrees Celsius – hot enough to leave us truly cooked.

He believes what will eventually occur on Earth already happened on the planet Venus about two to four billion years ago.

Goldblatt acknowledges that his theory doesn't' take into account unforeseeable event, such as nuclear war or massive asteroid impacts.

Goldblatt will present his theory, "The Physics and Chemistry of the Apocalypse: Runaway Greenhouses," during a seminar at the university on Tuesday.

Meanwhile, scientists at the University of Cambridge have an altogether different theory. They suggest that global warming might be helping to stave off another ice age, ensuring that large ice sheets and glaciers don't begin covering the Earth.

Researchers from the school's Department of Earth Sciences suggest that Earth is just about due for another ice age. The planet has typically gone about 11,000 years between ice ages and it's now been 11,600 years since the last one.

But they say human-made carbon dioxide emissions are keeping it at bay

Writing in a paper published in Nature Geoscience, the scientists say that carbon dioxide levels have been rising for about 8,000 years and accelerated sharply with the industrial revolution.

Those rising CO2 levels mean the next ice age is unlikely to begin for at least 1,500 years, because CO2 levels are too high to allow an increase in the volume of ice sheets.