Many people, including some scientists, hope that new technologies will help with the global warming problem -- at least will buy time to make other changes.Recently, there have been a number of proposals aired for the development and deployment of technology which is designed to reduce global warming. Broadly, such technology is intended to do one of two things: 1) Decrease the warming due to the increase in CO2 by decreasing the solar input to the planet; or 2) Mitigate the CO2 increase directly by increasing its sequestration or removal from the atmosphere.
There was a review of this issue at a recent symposium at the annual meeting of the American Association for the Advancement of Science (AAAS) in San Diego (2010).. The consensus of the meeting was that (1) was relatively easy to do but didn't attack the main problem, consequently or in addition had a lot of potential negative effects; and that (2) is harder to do and will take longer but has fewer side effects and will have to be undertaken in the long run anyway.
As for (1), there have been a number of proposals to decrease the solar input to the planet, for example, by putting trillions of mirrors in space, or (more plausibly) increasing the sulfate levels in the stratosphere as volcanoes do. However, all reflection ideas suffer the same two problems: The CO2 level in the atmosphere would continue to increase, so all the bad effects of that would continue, e.g., the acidification of the oceans. Because the CO2 isn't removed, any reflection measure must be continued forever or the temperature will skyrocket when it is stopped. The more different the CO2 level is from normal the more unstable the whole system will become.
As for (2), removal of the CO2 that we have added and will undoubtedly continue to add to the atmosphere will have to be undertaken anyway. First, because long term removal and sequestration of CO2 actually solves the problem. Second, because natural methods of removal will take too long: Current estimates are that an appreciable fraction of the excess CO2 signature that we have already added will remain in the atmosphere for hundreds or thousands of years (see section 5 for details).
There have been several proposals for CO2 sequestration. Some seem plausible until you think of the real-world consequences. An example is putting millions of wave-driven pumps into the ocean to pump the colder deep water to the surface (figure at top), so plankton can more easily live there. Can you imagine the effect on shipping of an ocean full of these things? How would our beaches fare after a number of these huge pipes drifted ashore after a storm?
The proposal that has been most tested in small scale at this time involves putting tons of small iron particles into the upper layers of the ocean. Iron is the limiting resource for many diatoms, so a phytoplankton bloom usually results when this is done. The iron seeding appears to result in the preferential growth of larger diatoms, which tend to settle to the bottom of the deep ocean, taking the CO2 they incorporated in their growth with them.
Recently, the commission formed by the 1972 London treaty -- the treaty which governs ocean waste dumping by ships and nations -- has asserted that it has jurisdiction on this issue. The commission has set up a procedure for applicants to follow. No one has filed yet for a global application.
All of the conference presenters also stressed the following problem. The most basic flaw of any technological mitigation is that, if it looks like it is possible, people and politicians will not be motivated to make the necessary conversion to a sustainable society. We will keep spewing more carbon dioxide into the air, and if the amount doubles every 31 years (section 5), the exponential increase will eventually overwhelm any technology put in place.
Second, it must be noted that all technological solutions have a carbon footprint of their own. All of them take energy and resources to employ. It doesn't matter if your particular energy source is green, if there is any polluting energy used anywhere on the planet, you are contributing to pollution if you use additional power for such a scheme -- either for producing materials or for maintaining the scheme. You must show that your total carbon footprint is negative, that you are removing carbon overall.
There are also all the possible legal/ liability issues, and some were discussed at the AAAS conference. If you cause or even if you stop a world-wide change in climate, at least some people will be negatively affected, or can plausibly claim to be. India in particular appears to be very sensitive about anything which might interrupt the annual monsoon upon which their agriculture depends. This monsoon is getting very fickle, and the fickleness is expected to worsen with global warming. Any deliberate implementation might be viewed as dangerous, tantamount to an act of war, by an affected country.
In the end, I think the solution is to move toward a sustainable society, not to create even more of a mess in or above the planet. I am not arguing that we shouldn't explore technology that may help us out of the mess that we are in, just that it cannot be the main part of the solution, because a move to a sustainable society is going to be necessary in any case.
There was a review of this issue at a recent symposium at the annual meeting of the American Association for the Advancement of Science (AAAS) in San Diego (2010).. The consensus of the meeting was that (1) was relatively easy to do but didn't attack the main problem, consequently or in addition had a lot of potential negative effects; and that (2) is harder to do and will take longer but has fewer side effects and will have to be undertaken in the long run anyway.
As for (1), there have been a number of proposals to decrease the solar input to the planet, for example, by putting trillions of mirrors in space, or (more plausibly) increasing the sulfate levels in the stratosphere as volcanoes do. However, all reflection ideas suffer the same two problems: The CO2 level in the atmosphere would continue to increase, so all the bad effects of that would continue, e.g., the acidification of the oceans. Because the CO2 isn't removed, any reflection measure must be continued forever or the temperature will skyrocket when it is stopped. The more different the CO2 level is from normal the more unstable the whole system will become.
As for (2), removal of the CO2 that we have added and will undoubtedly continue to add to the atmosphere will have to be undertaken anyway. First, because long term removal and sequestration of CO2 actually solves the problem. Second, because natural methods of removal will take too long: Current estimates are that an appreciable fraction of the excess CO2 signature that we have already added will remain in the atmosphere for hundreds or thousands of years (see section 5 for details).
There have been several proposals for CO2 sequestration. Some seem plausible until you think of the real-world consequences. An example is putting millions of wave-driven pumps into the ocean to pump the colder deep water to the surface (figure at top), so plankton can more easily live there. Can you imagine the effect on shipping of an ocean full of these things? How would our beaches fare after a number of these huge pipes drifted ashore after a storm?
The proposal that has been most tested in small scale at this time involves putting tons of small iron particles into the upper layers of the ocean. Iron is the limiting resource for many diatoms, so a phytoplankton bloom usually results when this is done. The iron seeding appears to result in the preferential growth of larger diatoms, which tend to settle to the bottom of the deep ocean, taking the CO2 they incorporated in their growth with them.
Recently, the commission formed by the 1972 London treaty -- the treaty which governs ocean waste dumping by ships and nations -- has asserted that it has jurisdiction on this issue. The commission has set up a procedure for applicants to follow. No one has filed yet for a global application.
All of the conference presenters also stressed the following problem. The most basic flaw of any technological mitigation is that, if it looks like it is possible, people and politicians will not be motivated to make the necessary conversion to a sustainable society. We will keep spewing more carbon dioxide into the air, and if the amount doubles every 31 years (section 5), the exponential increase will eventually overwhelm any technology put in place.
Second, it must be noted that all technological solutions have a carbon footprint of their own. All of them take energy and resources to employ. It doesn't matter if your particular energy source is green, if there is any polluting energy used anywhere on the planet, you are contributing to pollution if you use additional power for such a scheme -- either for producing materials or for maintaining the scheme. You must show that your total carbon footprint is negative, that you are removing carbon overall.
There are also all the possible legal/ liability issues, and some were discussed at the AAAS conference. If you cause or even if you stop a world-wide change in climate, at least some people will be negatively affected, or can plausibly claim to be. India in particular appears to be very sensitive about anything which might interrupt the annual monsoon upon which their agriculture depends. This monsoon is getting very fickle, and the fickleness is expected to worsen with global warming. Any deliberate implementation might be viewed as dangerous, tantamount to an act of war, by an affected country.
In the end, I think the solution is to move toward a sustainable society, not to create even more of a mess in or above the planet. I am not arguing that we shouldn't explore technology that may help us out of the mess that we are in, just that it cannot be the main part of the solution, because a move to a sustainable society is going to be necessary in any case.
DETAILS
The sketch at top is from a BBC article about the proposal.
COMMENTS:
Feb 7, 2010. Anonymous said.
It has to be sound policies, governed not only by technology but commonsense as the issue is too complex for anyone to predict WHEN things will happen (ie disasters etc) but you can only say with reasonable probability that it WILL. So if you are a reasonable person, you would you not get car insurance as there is reasonable probability that an accident will happen....this is the same thing. You hope you never have to use the insurance, but by golly...you BETTER buy the insurance!
Feb 12, 2010: David Mills said:
I agree that we should learn what we can do with technology, certainly I support pilot projects to try out some of the ideas. But, to push your analogy: I am afraid that having this as "insurance" is like giving your car keys to your teenager and telling them that all the damage is covered, go have a good time! An invitation to disaster, given the tendency of people to deny the problem.
Feb. 16, 2010, HD Brichto said:
could you comment specifically on Crutzen's endorsement of the various sulpher dioxide seeding proposals.
They seek to balance the release of stored planetary energy with reduction of solar gain energy. Do they figure in the reduction in the arctic albedo effect due to increased particulate pollution?
Feb 23, 2010: David Mills replied:
The consensus at the last AAAS meeting was that carbon sequestration was the best long-term strategy, and not reflection schemes. Carbon sequestration or removal will be needed in any case because otherwise the excess will stay in the atmosphere a very long time. Solar reflection just might make the problem worse in the long run, won't solve the problem of the acidification of the ocean caused by CO2 at all,and would never be agreed to by all nations anyway. Sorry, reflection schemes seem DOA at this point.
It has to be sound policies, governed not only by technology but commonsense as the issue is too complex for anyone to predict WHEN things will happen (ie disasters etc) but you can only say with reasonable probalility that it WILL. So if you are a reasonable person, you would you not get car insurance as there is reasoable probability that an accident will happen....this is the same thing. You hope you never have to use the insurance, but by golly...you BETTER buy the insurance!!
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