On a quick read, it seems mostly sensible. A few points (which I should make formally):
*Climate change poses an increasingly severe range of threats to biodiversity and ecosystem services, with ~10% of species estimated to be at risk of extinction for every 1⁰C rise in global mean temperature.* My guess is that this statement is hard to support empirically. The argument would need to be about rates of change and not amounts of change. For example, we did not see 30 to 50% of species going extinct as a result of the 3 to 5 C warming coming out of the last glacial. This statement might be more supportable if it were phrased in terms of rates of change (e.g., "for every 1 C per century increase in the rate of warming") which was probably implicit in the minds of the writers. *Enhanced weathering would involve large-scale mining and transportation of carbonate and silicate rocks, and the spreading of solid or liquid materials on land or sea with major impacts on terrestrial and coastal ecosystems and, in some techniques, locally excessive alkalinity in marine systems.* I do not know of any evidence that spreading carbonate or silicate minerals in the land or sea would have major impacts on terrestrial and coastal ecosystems. Those of us who have considered using such approaches to ameliorate effects of ocean acidification on coastal communities have been somewhat dismayed at the difficulty of obtaining significant impact on coastal ecosystems -- impacts, by the way, that are anticipated to be beneficial to these ecosystems. The authors could echo the language from the afforestation bullet -- i.e., "impacts (postitive and negative) would depend on the method and scale of implementation." *Ocean storage of biomass (e.g. crop residues) would likely have negative impacts on biodiversity.* I do not know of any evidence to support this contention. While it could be true, I would guess that adoption of this approach would make the seafloor a more heterogeneous place and bring food to the seafloor. Both of these things could increase biodiversity. That said, we should not fall into the trap of thinking that more biodiversity is necessarily good. Introduced species often increase local biodiversity. The issue is helping natural ecosystems to persist, not increasing biodiversity. *The very fact that the international community is presented with geo-engineering as a potential option to be further explored is a major social and cultural issue*.* * Is this intended to be an empirically testable statement? If so, how do I determine what is a major social and cultural issue? War, poverty, justice, freedom, geoengineering? *Climate change could be addressed by a rapid and significant reduction in greenhouse gas emissions through a transition to a low-carbon economy with overall positive impacts on biodiversity. Measures to achieve such a transition would avoid the adverse impacts of climate change on biodiversity *. Even with a hypothetical rapid transition, much more climate change is in the pipeline. Should read: "Measures to achieve such a transition would REDUCE adverse impacts of climate change on biodiversity. " *The deployment of geo-engineering techniques, if feasible and effective, could reduce some aspects of climate change and its impacts on biodiversity. At the same time, geo-engineering techniques are associated with their own negative impacts on biodiversity*. *The net effect will vary among techniques and is difficult to predict. * Again, these negative effects have not been demonstrated for all possible deployments. At the very least , "At the same time, DEPLOYMENTS OF geo-engineering techniques COULD BE associated with their own negative impacts on biodiversity." _______________ Ken Caldeira Carnegie Institution Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA +1 650 704 7212 kcalde...@carnegie.stanford.edu http://dge.stanford.edu/labs/caldeiralab @kencaldeira *YouTube:* Crop yields in a geoengineered climate<http://www.youtube.com/watch?v=-0LCXNoIu-c> Influence of sea cucumbers on a coral reef CaCO3 budget<http://www.youtube.com/watch?v=-FSd4zy8iMo> On Fri, Jan 27, 2012 at 8:43 AM, Andrew Lockley <and...@andrewlockley.com>wrote: > The CBD report on geoengineering is open for a second and final round of > review comments: http://www.cbd.int/climate/geoengineering/review/ > > Pls comment, esp on the exec summary > > A > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to geoengineering@googlegroups.com. > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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