By David L. Brown
Surely one of the most important issues facing us today — and one of the least discussed in mainstream media and public forums — is the threat posed by rising amounts of CO2 and other greenhouse gases (GHG) in our planet’s atmosphere. CO2 has been identified as a major problem, reaching levels that have been clearly demonstrated to be causing global warming.
There is no longer any doubt that global warming is real and is taking place now. The evidence lies in melting glaciers everywhere, the receding Greenland Ice Sheet and breakup of huge ice floes along the fringes of Antarctica, and many other clear signals. Rising GHG comes in large part from the burning of fossil fuels which releases carbon long sequestered in the Earth into the air. Other factors include forest destruction and slash-and-burn agriculture.
The best course of action, many scientists agree, would be to “bury” the excess CO2, either before it enters the atmosphere or by removing it from the air. The question is, where to put it? Proposals have included the use of abandoned oil wells, coal seams and salt mines. But according to an article in this week’s edition of New Scientist magazine, the best place would be deep in the oceans, where high pressures and low temperatures would liquify the gas or lock it up in frozen hydrates by combination with water. According to the article:
Even earthquakes would not shift it, says Kurt House, a geoscientist at Harvard University. Better still, the available storage space is vast. The US could store thousands of years of emissions within its own territorial waters, he says (Proceedings of the National Academy of Sciences).
One worry is that if climate change warms up the oceans, the stored hydrates might be released back into the atmosphere, as might also happen with the methane hydrates that are already deep in the sediment. House says the bottom of the ocean would have to warm by more than 5 °C for that to happen “which is very unlikely”. Injecting CO2 into methane hydrates should be avoided, though, as it could destabilise them.
This last point raises a potential problem, since the ocean floor is already home to vast quantities of methane hydrates. If these should be disturbed and release the sequestered methane, it could initiate a significant increase in atmospheric GHG — and methane is a greenhouse gas 24 times more efficient than CO2.
A program to sequester CO2 on a global basis and in quantities large enough to stabilize or even reduce CO2 levels would undoubtedly be the most ambitious project ever undertaken. The cost would be extraordinary — but the question must be asked: What price will we pay if GHG is allowed to continue to rise? Continuing to do nothing no longer seems to be an option.