There's a nasty feedback here. Whereas the carbon sinks act, through negative feedback, to absorb around 50% of CO2 emissions into the atmosphere, these same sinks will re-emit the CO2 if CO2 is taken out of the atmosphere. Thus if 2 GtC is emitted by us, 1 GtC is absorbed by sinks, but if then 2 GtC are taken out of the atmosphere by us, 1 GtC will be re-emitted by the sinks.
At least, that's what I reckon. Cheers, John ----- Original Message ----- From: Alvia Gaskill To: Ken Caldeira Cc: [email protected] Sent: Monday, December 15, 2008 8:32 PM Subject: [geo] Re: Ocean Fertilization, an Incomplete Answer with Uncertain Long Term Implications Say Aussies Regarding the "absorption limit" for OIF, what should be the baseline against which the effectiveness of OIF is evaluated? Should it be the total of human CO2 emissions, the total of all human GHG emissions or should it be the amount of CO2 that is added to the atmospheric inventory annually? If the maximum quantity that can be captured by OIF enhanced plankton is constant, wouldn't the percent effectiveness decrease as human emissions increase as they likely will and also, as the natural sinks become less effective? I participated in a discussion recently regarding this issue, although not about OIF specifically. The decision was to base the effectiveness on the amount of CO2 added to the air and not the total emissions, assuming that about half the emissions wind up in the air. This also relates to how carbon credits from OIF would be calculated. Do the credits apply to the emissions or to the amount added to the air? Example calculations to illustrate these points: 1GtC from OIF/4GtC added to air each year in 2008 = 25% 1GtC/8GtC emitted by humans in 2008 = 13% 1GtC/6.66GtC as CO2 emitted by humans in 2008 = 15% 1GtC/16GtC emitted by humans in 2050 (arbitrary emissions and date, not any specific scenario) = 6% OIF gets a lot of attention for a technology that will never remove more than 25% of CO2 added to the atmosphere. ----- Original Message ----- From: Ken Caldeira To: [email protected] Cc: [email protected] Sent: Monday, December 15, 2008 1:00 PM Subject: Re: [geo] Ocean Fertilization, an Incomplete Answer with Uncertain Long Term Implications Say Aussies And while we are thinking deeply about this potential threat, we will continue to strip mine the ocean of edible fish. I am not a big fan of ocean fertilization, but I do not think that anybody has come up with any plausible damage from a well-managed ocean fertilization program that is of the same order-of-magnitude as what we are already routinely doing to the ocean with overfishing. I am even less clear on what the "irreversible risk" is supposed to be from a well-managed ocean fertilization program. Assuming that you monitor for anticipated risks, what could happen that would not be likely to reverse itself after fertilization ceases? [ By well-managed, I mean that endemic species abundances and oxygen contents and things like that are being monitored, so that you do not induce extinctions ... which are irreversible. ] [ This is not an excuse to induce more damage, but just a comment to note that attention to various potential risks are often incommensurate with the amount of actual risk incurred. ] On Mon, Dec 15, 2008 at 5:29 AM, Alvia Gaskill <[email protected]> wrote: http://www.alertnet.org/thenews/newsdesk/SP39844.htm RPT-FEATURE-Scientists urge caution in ocean-CO2 capture schemes 15 Dec 2008 13:04:25 GMT Source: Reuters (Repeats story that moved at 0000 GMT) By David Fogarty, Climate Change Correspondent, Asia SINGAPORE, Dec 15 (Reuters) - To some entrepreneurs, the wild and icy seas between Australia and Antarctica could become a money spinner by engineering nature to soak up carbon dioxide and then selling carbon credits worth millions of dollars. To some scientists and many nations, though, the concept of using nature to mop up mankind's excess CO2 to fight global warming is fraught with risk and uncertainty. An analysis by a leading Australian research body has urged caution and says more research is crucial before commercial ventures are allowed to fertilise oceans on a large scale and over many years to capture CO2. "I don't think the scientific community has even sat down and made a list of the things we need to check before we feel comfortable that this would be a low-risk endeavour," said one of the Australian report's authors, Tom Trull. "We never even designed measurement programmes to look at ecological change and the risks," said Trull, Ocean Control of Carbon Dioxide programme leader at the Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC) in Hobart. Scientists say sprinkling the ocean surface with trace amounts of iron or releasing other nutrients over many thousands of square kilometres promotes blooms of tiny phytoplankton, which soak up carbon dioxide in the marine plants. When the phytoplankton die, they drift to the ocean depths, along with the carbon locked inside their cells where it is potentially stored for decades or centuries in sediments on the ocean floor. Firms eyeing this natural carbon sink hope to commercialise it to yield carbon credits to help industries offset their emissions. The problem is no one knows exactly how much carbon can be captured and stored in this way, for how long, or the risks to ocean ecosystems from such large-scale geo-engineering. Some scientists fear such schemes could change species composition in the oceans, increase acidity or cause oxygen depletion in some areas, even promote the release of another powerful greenhouse gas, nitrous oxide. BLOOMING "Ocean fertilisation may cause changes in marine ecosystem structure and biodiversity, and may have other undesirable effects," says the ACE CRC position analysis on ocean fertilisation science and policy, soon to be publicly released. "While controlled iron fertilisation experiments have shown an increase in phytoplankton growth, and a temporary increase in drawdown of atmospheric CO2, it is uncertain whether this would increase carbon transfer into the deep ocean over the longer-term," it says. It also says the potential for negative impacts is expected to increase with the scale and duration of fertilisation. There are doubts that any damaging effects could be detected in time. "It is very important to recognise that if deleterious effects increase with scale and duration of fertilization, detection of these cumulative effects may not be possible until the damage is already done," said John Cullen, professor of oceanography at Dalhousie University at Nova Scotia in Canada. "It is extremely important to look at the ecological risks of this kind of activity," he said. Oceans soak up vast amounts of CO2 emitted by nature or through burning of fossil fuels and deforestation and the Southern Ocean plays the greatest role of all the oceans. But much of the Southern Ocean is depleted of iron and experiments have shown even small amounts of the nutrient can trigger phytoplankton blooms that can last for up to two months. Companies such as California-based Climos and Australia's Ocean Nourishment Corp are planning small-scale experiments to test their ocean carbon capture and sequestration projects. Ocean Nourishment uses ammonia and urea, delivered via a marine pipeline to a region deficient in nitrogen, to boost phytoplankton growth and boost fish stocks. Climos uses iron and plans experiments in the Southern Ocean in 2010. "Iron fertilization is no silver bullet for climate change -- which underscores the severity of the problem we have, and the urgency for immediate emissions reductions worldwide," Climos founder and CEO Dan Whaley told Reuters in an email interview. But he said it was premature to judge iron fertilisation as dangerous. "Phytoplankton are nature's way of sequestering CO2 to the deep ocean, where nearly 90 percent of earth's carbon lies. Further, most everything we put up in the air is going to the deep ocean eventually. The only question is how long it takes," he said. (For separate Q&A with Climos, click on [ID:nSP376631]) Many nations, though, remain cautious and member states of two treaties that govern dumping of wastes at sea passed a non-binding resolution in October calling for ocean fertilisation operations to be allowed only for research. Parties to the London Convention and related London Protocol, part of the International Maritime Organisation, signed the resolution that said member states were urged to use "utmost caution" to evaluate research proposals to ensure protection of marine life. ABSORPTION LIMIT Trull, who participated in the first ocean fertilisation experiment in 1999, one of a dozen since conducted globally, said commercial ventures would need to operate over huge areas of ocean for many years. The ACE CRC report also says ocean fertilisation just using iron would likely hit an absorption limit of about 1 billion tonnes of carbon (3.7 billion tonnes of CO2) annually, or about 15 percent of mankind's total carbon emissions. "That really puts the risk in context. We're talking about altering ecosystems of planetary scale for a benefit that won't actually relieve us from dealing with all the other issues, such as conservation or alternative energy generation." Cullen of Dalhousie University said studies suggested that to sequester large amounts of carbon would require fertilisation of most of the Southern Ocean for long periods of time. "The question is can we assess those large-scale and long-term effects on the basis of experiments 100 by 200 km (60 by 120 miles) in size. I have not seen evidence it can be done." (Editing by Megan Goldin) --~--~---------~--~----~------------~-------~--~----~ 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] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
