Andrew, Thank you for posting this.
My take on the relevant conclusions of that article as they pertain to SRM: "Anoxia is closely tied to temperature, so, if we can control temp than we can control anoxia." My response: This may be the case, however, this is a narrow view of SRM's impact on the ocean. If SRM is initiated without concurrent reductions in CO2 emissions, than the ocean will increase its uptake of CO2 beyond that which would have occured without SRM. With this logic, one could argue that SRM may increase ocean acidification, which could also lead to a mass extinction event. Neither this paper nor the recent GeoMIP paper that you posted on August 4th discuss acidification, and the GeoMIP paper explicitly states that their research insufficiently accounts for complex interactions within the ocean system. I am no expert on this material, and, if the experts have concluded that ocean acidification no longer poses a large threat of marine/Earth extinction, then I retract my statement. However, everything that I have read up to this point confirms these thoughts. And, as an aside, there are many global catastrophes that could result in human extinction, anoxia perhaps being one. Thanks again, Tim On Wednesday, August 1, 2012 11:56:35 AM UTC-4, andrewjlockley wrote: > > The paper below could imply that SRM would help avoid ocean anoxia. I > personally believe that anoxia in a high carbon future could pose a serious > risk of human extinction. I know of no comparable threat to species > survival. > > I think some specific modelling in this regard would be very helpful. > It's a threshold we can't afford to cross, and therefore seems to offer a > strong argument for geoengineering. > > A > > www.annualreviews.org/doi/abs/10.1146/annurev.earth.36.031207.124256 > > Oceanic Euxinia in Earth History: Causes and Consequences > Annual Review of Earth and Planetary Sciences > > DOI: 10.1146/annurev.earth.36.031207.124256 > Katja M. Meyer and Lee R. Kump > > Euxinic ocean conditions accompanied significant events in Earth history, > including several Phanerozoic biotic crises. By critically examining modern > and ancient euxinic environments and the range of hypotheses for these > sulfidic episodes, we elucidate the primary factors that influenced the > generation of euxinia. We conclude that periods of global warmth promoted > anoxia because of reduced solubility of oxygen, not because of ocean > stagnation. Anoxia led to phosphate release from sediments, and continental > configurations with expansive nutrient-trapping regions focused nutrient > recycling and increased regional nutrient buildup. This great nutrient > supply would have fueled high biological productivity and oxygen demand, > enhancing oxygen depletion and sulfide buildup via sulfate reduction. As > long as warm conditions prevailed, these positive feedbacks sustained > euxinic conditions. In rare, extreme cases, euxinia led to biotic crises, a > hypothesis best supported by evidence from the end-Permian mass extinction. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To view this discussion on the web visit https://groups.google.com/d/msg/geoengineering/-/mXuA7TZq5HoJ. 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.
