Sunday, August 15, 2010

Hottest

Have we passed the tipping point for runaway climate change?

The evidence is still "hotly" debated. (Ow! Pun damage!)

The biggest clue will be a massive release of methane into the atmosphere, due to the melting of permafrost and ocean deposits of ice. Once the methane starts to bubble up from the continental shelves in large amounts, the process escalates on its own. At that point, nothing we do can stop it.

We know what will happen, because it happened before. The PT Mass Extinction Event. (Note: there is a lot of information about this on the internet. Google it and read as much about it as you can stand. It is worth knowing.)

The part about the greenhouse-like warming of the atmosphere and oceans is not hard to grasp. But what caused the oxygen to go away? The O2 content at the end of the Permian was close to 30%. Within a million years it had dropped to 10%. This means it was not the heat or climate change or habitat change that killed off more than 99% of all life on Earth at that time. Most creatures just suffocated, or at least became so weak from lack of oxygen that they could not survive.

Again, methane is the key. When you release methane into an oxygen-rich atmosphere, it degrades over time, becoming CO2 and water vapor.

Huh? How does that happen? And what does that have to do with oxygen?

Methane molecules are the simplest form of hydrocarbon. CH4. That means 1 carbon atom plus 4 hydrogen atoms. The free oxygen in our atmosphere is in the form of O2, that means 2 oxygen atoms bound together to make a molecule. In order for methane to change into carbon dioxide and water, it needs to suck up 2 oxygen molecules. That means each molecule of methane will take 2 molecules of oxygen out of our atmosphere.

Both CO2 and water vapor in the lower atmosphere also act as greenhouse gases, so just because the methane eventually goes away does not mean things go back to normal.

But this whole scenario will take about a million years to play out, right?

Burning fossil fuels has been converting O2 to CO2 since the start of the industrial age, so have seen some loss of oxygen already.

When the methane surge hits, that process will be accelerated.

And remember, once the atmospheric oxygen drops below 19.5%, people will start passing out on the street from hypoxia.

That's not a 20% drop. That's only half a percent.

We don't have a million years.

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