This week, the EPA agreed to consider ocean acidification as a water quality issue that can be addressed under the clean water act. This move by the EPA is part of a settlement of a lawsuit brought against the EPA by the Center for Biodiversity in Washington State. The Center for Biodiversity sued the EPA for not protecting coastlines against ocean acidification, which is a direct result of increasing CO2 in the atmosphere. This settlement means that the EPA will consider ways states can limit the CO2 pollution that is cause the acidification. What's so interesting about this problem is that the amount of CO2 already in the atmosphere is predicted by scientists to be great enough to cause the ocean pH to fall to levels dangerous to organisms that make shells. This means, even if we stop burning carbon tomorrow, there is still enough CO2 in the atmosphere NOW to cause a problem. This fact makes ocean acidification different than other climate change issues. It is not a prediction like how warm the surface ocean will be in 20 years or what percentage of CO2 in the atmosphere will be - it is a value that can be measured now.
So, the only way to prevent ocean acidification would be to take CO2 out of the present atmosphere. That is not an easy task. A lot of ideas have been proposed to engineer this CO2 removal, which is often called carbon sequestration. Some people suggest pumping it to the bottom of the ocean or liquefying it and pumping it deep into the ground. Other, more realistic solutions include removing CO2 by stimulating plant growth. This can be in the form of carbon credits for leaving preexisting forests or planting new forests. Other, popular proposed solutions involve growing algae. One option involves fertilization of the areas of the ocean were algae are not blooming due to nutrient limitation. Usually, these "deserts" in the ocean are limited by iron, and experiments where iron is added stimulates algal blooms. Now this does, in the short term, allow the algae to facilitate the removal of CO2 out of the atmosphere as they grow. However, it is unclear how long the CO2 stays out of the atmosphere, because other organisms eat the blooming algae or the sinking biomass after the algae die, sending that CO2 right back to the atmosphere - just like we exhale CO2 sequestered in plants like spinach after we eat them.
What may be one of the best solutions for carbon sequestration is controlled algae growth. This means growing lots of algae in bioreactors where we have control over the resulting biomass. Many of us in the algae biofuels industry are trying to do just this, in order to provide a feedstock for biofuel. If we "sequester" the CO2 this way, again, the CO2 will be returned to the atmosphere once it is burned as a fuel. If the CO2 to grow the algae didn't come from the atmosphere but from the smoke stacks of power plants that are emitting CO2 from burning coal or natural gas, the biofuel that results from this process is carbon neutral. This helps curb the future emissions of CO2, but won't help us remove CO2 that is currently in the atmosphere.
The only way then for carbon sequestration from algae to be a reality for reducing current CO2 levels, is for it to be more valuable for us as a society to produce a bunch of biomass for long term burial (on the order of millions of years) rather than for more fuel. Burying biomass is not currently economical and won't be until we place more value on reducing atmospheric CO2 than having fuel. This is where cap and trade comes in. Our government can decide pass legislation to cap the amount of emissions any one company can produce and then if they produce more than that, they can trade for other, more efficient companies allotted emissions, or buy off their extra emissions with carbon credits. This would require a lot of work by the government and a lot of cooperation on the part of industry...... and will be the topic of another post....
http://www.nytimes.com/aponline/2010/03/11/us/AP-US-EPA-Acid-Oceans.html?_r=1&scp=5&sq=EPA%20lawsuit&st=cse
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