The Martlet

Will the world end in 2012? Not according to Colin Goldblatt, an assistant professor in UVic’s School of Earth and Ocean Sciences. However, an apocalypse will eventually hap- pen. People just have to be a bit more patient . . . to the tune of 500 million years.

Goldblatt was the host of a recent Cafe Scientifique lecture, “The Physics and Chemistry of the Apocalypse,” which addressed the Earth’s ultimate future.

“This problem, it’s about the future of Earth, which is why we’re talking about it as the apocalypse,” ex- plains Goldblatt. “And it’s the history of Venus, and it’s something we’re going to see in the atmospheres of extra- solar planets, planets around other stars, which we’re going to be able to observe in the next five to 25 years.”

Goldblatt claims high- er output from the sun is what will do the Earth in. In 500 million years’ time, the Sun’s output will have increased by about 10 to 15 percent, and this will start a process leading to what is called a runaway greenhouse effect. As the Earth absorbs more energy from the sun, its surface temperature will heat up, creating more water vapour in the atmosphere, which, as it builds up, will prevent extra heat from escaping into outer space.

“Once we get to a very hot atmosphere that’s got a lot of water vapour in it, then you essentially block that [release of heat into space] off,” explains Goldblatt. “The only place you get heat out to space from is the upper atmosphere. But because you’ve gone to an atmosphere that’s tending toward the pure steam atmosphere, because you’re evaporating so much, you end up with a fixed temperature pressure profile in the upper atmosphere. And that means you have a fixed amount of heat that you can get out to space.” As Goldblatt explains, any humans that are unfortunate enough to be living on Earth 500 million years from now will not experience an immediate change. The Earth will reach a tipping point where rapid change will occur, but this tipping point would last centuries.

“It’s not going to happen overnight, because it takes a lot of energy to boil water, to make steam. You’ve still got to get that energy from the sun,” says Goldblatt. “It’s very rapid on a geological time-scale, but probably still longer than human lifetimes.”

But once things do get cooking, the Earth would be a much different place than it is now.

“Then we’ll get up to the critical point of water, that’s 647 degrees Kelvin [374°C], and at that point, liquid water and vapour become indistinguishable,” says Goldblatt. “So that’s it for the ocean; it’s all atmosphere now. And we’ll keep getting warmer, and then we’ll get to a point where carbonate rock — limestone, chalk, that kind of thing — starts to break down and release CO2. That’s like what hap- pens in a limekiln. You bake limestone to make lime, and that releases carbon dioxide.”

Goldblatt explains that at that point, the Earth’s atmo- sphere would be about 300 times thicker than it is today.

“And then that’s it! We have Venus,” he says.

While Goldblatt says that some life will be able to survive the increased heat, nothing on Earth will survive its eventual surface temperature of 1100°C. “Once we get into a runaway greenhouse, that really is the end. No life will survive that.”

Goldblatt says that scientists have been able to determine that Venus, the most Earth-like planet in the solar system in terms of size and atmosphere, once suffered a similar fate. These results were determined by observing the characteristics of its atmosphere. The runaway greenhouse effect would have occurred earlier due to Venus being closer to the sun.

“It looks like a kind of Earth that’s been cooked, basically,” says Goldblatt.

And while the Cafe Scientifique event definitely had a provocative title, what Goldblatt was discussing was by no means alarmist. He points out that human-caused climate change, although a cause for concern, would not lead to this same effect.

“Is climate change going to cause a runaway greenhouse, or any other kind of apocalypse? No,” says Goldblatt. “There’s not going to be any kind of physically driven apocalypse that’s going to come from climate change.

It’s going to be an ordinary danger we know how to deal with; it’s just as a society, we are refusing to deal with it.”

And as to other apocalyptic theories floating around that a quick YouTube search could turn up, Goldblatt dismisses these pseudo-scientific conspiracy theories, saying that making good use of science would dispel that kind of thinking.

“If there’s any kind of conspiracy theory on the apocalypse, I’m not in on it,” jokes Goldblatt. “You know, the most secret thing when I worked at NASA was where you could get the best beer on base.”