Nov. 11th, 2010

erinlefey: (Default)

AKA: Mentos and Diet Coke cause the deaths of millions

Do I have your attention? Not yet? I will. I'd like to share with you the most recent way I've learned that the Earth can fuck you up.

Exploding Lakes.

Technically they're called limnic eruptions. I include the link so you'll realize I'm not making up this thing out of my fevered imagination, go check it out later.

Here's what's involved:
1) A lake with CO2 (carbon dioxide) saturated water coming in.
2) A lake where the local temperature doesn't really change much. Think equatorial.
3) A volcano or fault line nearby that can make the lake rattle on occasion.

That's it! A recipe for disaster! Why? Well, CO2 saturated water is heavier than oxygenated water, so it sinks to the bottom. In the overwhelming majority of lakes, seasonal differences change the temperature of the lake, and it "turns over", gradually releasing the stored gases and moving the oxygenated water throughout the lake.

In three lakes in the world, Lake Monoun, Lake Nyos, and Lake Kivu, CO2 saturated water comes in and the lake does not "turn over" seasonally. This means the CO2 stays at the bottom of the lake, under increasing pressure. The water at the bottom of the lake becomes saturated with the carbon dioxide over the course of years, pressurized like the soda in a bottle of Diet Coke.

Then something nearby rattles. A fault line. A minor earthquake. A mudslide. Whatever. It rattles the lake enough that a bit of the pressurized CO2 saturated water comes to the surface. That acts as the Mentos in the Diet Coke bottle. Boom. The entire lake surface then looks like the bottle top of that Diet Coke bottle. A surface-wide geyser of carbonated liquid shoots hundreds of feet in the air. The lake level can drop by as much as three meters due to the removal of all of that pressurized CO2.

Awesome, huh? Jamie and Adam of Mythbusters should totally do this!

Well, except for the mass death. Why? CO2 is heavier than oxygen. All of that realized CO2 comes out as a huge invisible cloud, and it hugs the ground. It will gradually be dissipated into the surrounding atmosphere. But until it does, it is pulled by gravity, slowly coasting downhill.

Did I mention that animals, including my favorite species Homo Sapiens, cannot breathe CO2?

Lake Monoun's eruption in 1984 killed 37 people. Lake Nyos' eruption in 1986 killed about 1,800. The latter eruption released 80 million cubic meters of CO2. The cloud passed through valleys and villages, where people realized they were breathing oddly, were briefly puzzled, and then fell over dead. People were killed as far as 15 miles away

Now here's the kicker: The third lake, Lake Kivu, hasn't erupted in centuries so far as we know. Geologists, now that they know what to look for, have solid evidence of mass extinctions in the area every 1000 years or so. Lake Kivu is 2000 times larger than Lake Nyos. There are 2 million people living along it's shores. How's that for a potential disaster?

There's a way to degass Lake Kivu. Pretty easy, actually. Stick a huge pipe in it like a straw, pump up some of the water from the bottom, and as the CO2 saturated water comes up, it does the Mentos/Diet Coke trick into the air. You can even turn off the pump at that point, it will be self-sustaining.

But the cost is high, as you'd need dozens of such pipes. And it's hard to find money for anything in that region, let alone for some hypothetical future disaster avoidance. So, sometime in our lifetime or in our children's lifetimes, millions of people will die in Africa at one instant, due to an exploding lake.

Earth is a terrifying place to live.


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