Saturday, October 27, 2007

We're full up!

By Carl

This is really bad news, because carbon sequestration was one possible way to prevent a worsening global warming crisis:

Carbon dioxide (CO2) levels in the atmosphere have risen 35% faster than expected since 2000, says a study. International scientists found that inefficiency in the use of fossil fuels increased levels of CO2 by 17%.

The other 18% came from a decline in the natural ability of land and oceans to soak up CO2 from the atmosphere.

About half of emissions from human activity are absorbed by natural "sinks" but the efficiency of these sinks has fallen, the study suggests.

Imagine a sponge. Drip water on the sponge when it's dry and not much of it gets out. The sponge absorbs a lot of the water.

Now imagine that sponge is as full as it's going to get. The water basically just rolls off the sponge.

That's what we've done with our carbon sinks. What are those sinks? Well, the oceans, for one. Remember, carbon isn't only created in the form of carbon dioxide. We've been dumping megatons of carbon in other forms into our oceans in industrial and human wastes.

Yup. You crap carbon.

Carbon has an unique ability to bond with other elements. In a balanced system, this can work miracles.

For example, take one atom of carbon and one of calcium, and you have the building blocks of a coral reef.

But, take TWO carbon atoms and one calcium atom and you get calcium bicarbonate, which works great on your stomach acid, but actually destroys coral.

Too, the oceans do a massive job of scrubbing the atmosphere. Plankton, which are probably the simplest form of vegetation on the planet, commit photosynthesis, taking carbon dioxide out of the air, and converting it to oxygen, absoring the carbon for use in their calcium carbonate skeletons. Thus starts the oceanic carbon cycle, ultimately sequestering massive amounts of carbon at the bottom of the ocean in decaying dead fish.

But look what has happened: as global warming has intensified the weather patterns over the oceans, winds have picked up. There's still plenty of carbon dioxide to go around, but it's harder for plankton to get at...after all, do you find it easier to eat when the boat is rocking?

Too, increasing carbon levels, particularly in the form of carbon dioxide, makes the oceans more acidic, which kills off the plankton. So you have fewer plankton, more carbon, and it's harder to get at.

Worse. Right now, the carbon that is sequestered deep in the ocean stays deep in the ocean because of temperature and density differences between the top and bottom waters, effectively forming a wall that mostly prevents mixing except where the oceans upwell and then over geologic time scales. If temperatures begin to rise higher in the ocean, the forces that created this halocline will cease functioning, which means that the oceanic waters will start mixing up more, bringing more carbon up to the ocean surfaces.

Which sinks (pardon the pun) any chance of using the deep oceans to store carbon that we might scrub out of our wastes.

Another sink, of course, is vegetation, which absorbs carbon dioxide as well as carbon in the soil (this is partially how burned forests bounce back so quickly). Any vegetation will do this, but trees are particularly efficient at scrubbing carbon out of the air and ground: extensive canopies, root systems, and large energy needs combine to make them oxygen factories.

Here, too, weather has played a prominent part, because as the earth warms...well, let's take a quick look at the hydrological cycle: temperatures rise, water evaporates, clouds form, rain falls. Basic physics tells us that warmer air can absorb more moisture, so literally, evaporation starts to suck the moisture out of the ground, parching the land. Now you have plants dying of thirst. Too, you have a higher risk of wildfires (we've seen that this week), which destroy vegetation outright.

Remove vegetation, either through clearing land or burning it out or simply creating a new desert, and you remove a major carbon sink.

We've reached, and passed, a tipping point in global warming, and I think there are some problems man cannot solve.

(Cross-posted at Simply Left Behind.)

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