I thought Professor Calvin's paper was superb and have extracted the summary of main points below. Information on Professor Calvin's other writings is at http://en.wikipedia.org/wiki/William_H._Calvin On the push-pull pipe sequestration idea, I think wave and tide power have more potential than wind as a pumping energy source. Robert Tulip William Calvin wrote: emissions reduction ... has become a largely ineffective course of action with poor prospects... Most of the growth in emissions now comes from the developing countries burning their own fossil fuels to modernize with electricity and personal vehicles. Emissions growth is likely out of control, though capable of being countered by removals elsewhere. > >...drastic emissions reduction worldwide would only buy the US nine extra >years. However useful it would have been in the 20th century, emissions >reduction has now become a failed strategy, though still useful as a booster >for a more effective intervention. > >We must now resort to a form of geoengineering that will not cause more >trouble than it cures, one that addresses ocean acidification as well as >overheating and its knock-on effects. Putting current and past CO2 emissions >back into secure storage would reduce the global overheating, relieve deluge >and drought, reverse ocean acidification, reverse the thermal expansion >portion of sea level rise, and reduce the chance of more abrupt climate >shifts. > >Existing ideas for removing the excess CO2 from the air appear inadequate: too >little, too late. They do not meet the test of being sufficiently big, quick, >and secure. There is, however, an idealized approach to ocean fertilization >that appears to pass this triple test. It mimics natural up- and down-welling >processes using push-pull ocean pumps powered by the wind. One pump pulls >sunken nutrients back up to fertilize the ocean surface—but then another pump >immediately pushes the new plankton production down to the slow-moving depths >before it can revert to CO2. > >...The atmospheric CO2 is currently above 390 parts per million and the excess >CO2 growth has been exponential. Excess CO2 is that above 280 ppm in the air, >the pre-industrial (1750) value and also the old maximum concentration for the >last several million years of ice age fluctuations between 200 and 280 ppm. > >Is a 350 ppm reduction target, allowing a 70 ppm anthropogenic excess, low >enough? We hit 350 ppm in 1988, well after the sudden circulation shift in >1976, the decade-long failure of Greenland Sea flushing that began in 1978, >and the sustained doubling (compared to the 1950-1981 average) of world >drought acreage that suddenly began in 1982. > >Clearly, 350 ppm is not low enough to avoid sudden climate jumps, so for >simplicity I have used 280 ppm as my target: essentially, cleaning up all >excess CO2. But how quickly must we do it? That depends not on 2°C overheating >estimates but on an evaluation of the danger zone we are already in. > >...big trouble could arrive in the course of only 1-2 years, with no warning. >So the climate is already unstable. (“Stabilizing” emissions is not to be >confused with climate stability; it still leaves us overheated and in the >danger zone for climate jumps. Nor does “stabilized” imply safe.) While >quicker would be better, I will take twenty years as the target for completing >the excess CO2 cleanup in order to estimate the drawdown rate needed. > >...we need to take back 600 GtC within 20 yr at an average rate of 30 GtC/yr >in order to clean up... we must find ways of capturing 30 GtC/yr with >traditional carbon-cycle biology, where CO2 is captured by photosynthesis and >the carbon incorporated into an organic carbon molecule such as sugar. Then, >to take this captured carbon out of circulation, it must be buried to keep >decomposing methane and CO2 from reaching the atmosphere. > >One proposal is to bundle up crop residue and sink the weighted bales to the >ocean floor. They will decompose there but it will take a thousand years >before this CO2 can be carried back up to the ocean surface and vent into the >air. Such a project, even when done on a global scale, will yield only a few >percent of 30 GtC/yr. Burying raw sewage is no better. > >...land-based photosynthesis, competing for space and water with human uses, >cannot do the job in time. It would need to be far more efficient than >traditional plant growth. At best, augmented crops on land would be an order >of magnitude short of what we need for either countering or cleanup. > >Because of the threat from abrupt climate leaps, the cleanup must be big, >quick, and secure. ...we must look to the oceans for the new photosynthesis >and for the long-term storage of the CO2 thus captured. > >Algal blooms are increases in biological productivity when the ocean surface >is provided with fertilizer containing missing nutrients...A sustained bloom >of algae can be fertilized by pumping up seawater from the depths... To settle >out another 30 GtC/yr, we would need about four times the current ocean >primary productivity. ... Our 41% CO2 excess is already too large to draw down >in 20 yr via primary productivity increases in the ocean per se. However, our >escape route is not yet closed off. There is at least one plausible prospect >for an emergency draw down for 600 GtC in 20 yr. It seeks to mimic the natural >ocean processes of upwelling and downwelling.
> >________________________________ > From: William H. Calvin <[email protected]> >To: [email protected] >Sent: Monday, 28 January 2013 11:51 AM >Subject: [geo] 1. Prospects for an Emergency Drawdown of CO2 > This is written for a less expert audience than seen here at Google Groups Geoengineering, but bear with me as this is an example of how to frame policy priorities. [email protected] ———— Suppose we had to quickly put the CO2 genie back in the bottle. After a half-century of “thinking small” about climate action, we would be forced to think big—big enough to quickly pull back from the danger zone for tipping points and other abrupt climate shifts. By addressing the prospects for an emergency drawdown of excess CO2 now, we can also judge how close we have already come to painting ourselves into a corner where all escape routes are closed off.7 Getting serious about emissions reduction will be the first course of action to come to mind in a climate crisis, as little else has been discussed. But it has become a largely ineffective course of action11 with poor prospects, as the following argument shows. In half of the climate models14, global average overheating is more than 2°C by 2048. But in the US, we get there by 2028. It is a similar story for other large countries. Because most of the growth in emissions now comes from the developing countries burning their own fossil fuels to modernize with electricity and personal vehicles, emissions growth is likely out of control, though capable of being countered by removals elsewhere. But suppose the world somehow succeeds. In the slow growth IPCC scenario, similar to what global emissions reduction might buy us, 2°C arrives by 2079 globally–but in the US, it arrives by 2037. So drastic emissions reduction worldwide would only buy the US nine extra years. However useful it would have been in the 20th century, emissions reduction has now become a failed strategy, though still useful as a booster for a more effective intervention. We must now resort to a form of geoengineering that will not cause more trouble than it cures, one that addresses ocean acidification as well as overheating and its knock-on effects. Putting current and past CO2 emissions back into secure storage5 would reduce the global overheating, relieve deluge and drought, reverse ocean acidification, reverse the thermal expansion portion of sea level rise, and reduce the chance of more4 abrupt climate shifts. Existing ideas for removing the excess CO2 from the air appear inadequate: too little, too late. They do not meet the test of being sufficiently big, quick, and secure. There is, however, an idealized approach to ocean fertilization5 that appears to pass this triple test. It mimics natural up- and down-welling processes using push-pull ocean pumps powered by the wind. One pump pulls sunken nutrients back up to fertilize the ocean surface—but then another pump immediately pushes the new plankton production down to the slow-moving depths before it can revert to CO2. How Big? How Fast? The atmospheric CO2 is currently above 390 parts per million and the excess CO2 growth has been exponential. Excess CO2 is that above 280 ppm in the air, the pre-industrial (1750) value and also the old maximum concentration for the last several million years of ice age fluctuations between 200 and 280 ppm. Is a 350 ppm reduction target12, allowing a 70 ppm anthropogenic excess, low enough? We hit 350 ppm in 1988, well after the sudden circulation shift18 in 1976, the decade-long failure of Greenland Sea flushing24 that began in 1978, and the sustained doubling (compared to the 1950-1981 average) of world drought acreage6 that suddenly began in 1982. Clearly, 350 ppm is not low enough to avoid sudden climate jumps4, so for simplicity I have used 280 ppm as my target: essentially, cleaning up all excess CO2. But how quickly must we do it? That depends not on 2°C overheating estimates but on an evaluation of the danger zone2 we are already in. The Danger Zone Global average temperature has not been observed to suddenly jump, even in the European heat waves of 2003 and 2010. However, other global aspects of climate have shifted suddenly and maintained the change for many years. The traditional concern, failure of the northern-most loop of the Atlantic meridional overturning circulation (AMOC), has been sidelined by model results20-22 that show no sudden shutdowns (though they do show a 30% weakening by 2100). While the standard cautions about negative results apply, there is a more important reason to discount this negative result: there have already been decade-long partial shutdowns not seen in the models. Not only did the largest sinking site shut down in 1978 for a decade24, but so did the second-largest site23,28 in 1997. Were both the Greenland Sea and the Labrador Sea flushing to fail together2, we could be in for a major rearrangement of winds and moisture delivery as the surface of the Atlantic Ocean cooled above 55°N. >From these sudden failures and the aforementioned leaps in drought, one must conclude that big trouble could arrive in the course of only 1-2 years, with no warning. So the climate is already unstable. (“Stabilizing” emissions4 is not to be confused with climate stability; it still leaves us overheated and in the danger zone for climate jumps. Nor does “stabilized” imply safe.) While quicker would be better, I will take twenty years as the target for completing the excess CO2 cleanup in order to estimate the drawdown rate needed. The Size of the Cleanup It is not enough to target the excess CO2 currently in the air, even though that is indeed the cause of ocean acidification, overheating, and knock-on effects. We must also deal with the CO2 that will be released from the ocean surface as air concentration falls and the bicarbonate buffers reverse, slowing the drawdown. Thus, I take as the goal to counter the anthropogenic emissions4,5 since 1750, currently totaling 350 gigatonnes of carbon. (GtC =1015g of Carbon=PgC.) During a twenty year project period, another 250 GtC are likely be emitted, judging from the 3% annual growth in the use of fossil fuels5 despite some efforts at emissions reduction. Thus we need to take back 600 GtC within 20 yr at an average rate of 30 GtC/yr in order to clean up (for the lesser goal of countering continuing emissions, it would take 10 to 15 GtC/yr). Chemically scrubbing the CO2 from the air is expensive and requires new electrical power from clean sources, not likely to arrive quickly enough. On this time scale, we cannot merely scale up what suffices on submarines. Thus we must find ways of capturing 30 GtC/yr with traditional carbon-cycle8 biology, where CO2 is captured by photosynthesis and the carbon incorporated into an organic carbon molecule such as sugar. Then, to take this captured carbon out of circulation, it must be buried to keep decomposition methane and CO2 from reaching the atmosphere. Sequestering CO2 One proposal26 is to bundle up crop residue (half of the annual harvest is inedible leaves, skins, cornstalks, etc.) and sink the weighted bales to the ocean floor. They will decompose there but it will take a thousand years before this CO2 can be carried back up to the ocean surface and vent into the air. Such a project, even when done on a global scale, will yield only a few percent of 30 GtC/yr. Burying raw sewage3 is no better. If crop residue represents half of the yearly agricultural biomass, this also tells you that additional land-based photosynthesis, competing for space and water with human uses, cannot do the job in time.5 It would need to be far more efficient than traditional plant growth. At best, augmented crops on land would be an order of magnitude short of what we need for either countering or cleanup. Big, Quick, and Secure Because of the threat from abrupt climate leaps, the cleanup must be big, quick, and secure. Doubling all forests might satisfy the first two requirements but it would be quite insecure—currently even rain forests4 are burning and rotting, releasing additional CO2. Strike One. We are already past the point where enhanced land-based photosynthesis can implement an emergency drawdown. They cannot even counter current emissions. Basically, we must look to the oceans for the new photosynthesis and for the long-term storage of the CO2 thus captured. Fertilization per se Algal blooms are increases in biological productivity when the ocean surface is provided with fertilizer containing missing nutrients15 such as nitrogen, iron, and phosphorus. A sustained bloom of algae can be fertilized by pumping up seawater5,16,19 from the depths, a more continuous version of what winter winds9 bring up. Currently about 11 GtC/yr settles out of the wind-mixed surface layer into the slowly-moving depths13 as plankton die. To settle out another 30 GtC/yr, we would need about four times the current ocean primary productivity. Clearly, boosting ocean productivity worldwide is not, by itself, the quick way to put the CO2 genie back in the bottle. Strike Two. Our 41% CO2 excess is already too large to draw down in 20 yr via primary productivity increases in the ocean per se. However, our escape route is not yet closed off. There is at least one plausible prospect for an emergency draw down for 600 GtC in 20 yr. It seeks to mimic the natural ocean processes of upwelling and downwelling. References (numbers refer to reference list in the following “Push-pull ocean pipes” Topic -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering?hl=en. 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