I am traveling and have not had a chance to read the Pongratz article closely yet, but it looks like the comparison is between a control scenario, a 2xCO2 world, and a 2xCO2 + stratospheric aerosols world. This is common practice, and the analytical logic is clear, however presenting model runs this way plays into the hands of critics who mischaracterize the policy choice as between mitigation and geoengineering. Opponents point to these results and portray researchers as supporting geoengineering as an alternative to mitigation - "or else why wouldn't emissions cuts be represented in the models?" Couldn't modelers include mixed mitigation/ geoengineering scenarios as a routine feature of such studies, to make it harder for critics to misrepresent things? After all, almost no one is arguing for intervention without emissions cuts.
Josh Horton joshuahorton...@gmail.com http://geoengineeringpolitics.blogspot.com/ On Jan 24, 4:09 pm, rongretlar...@comcast.net wrote: > Ken and list: > > 1. I have enjoyed the "Pongratz" article sent recently which is the subject > of this NPR interview given below. In it, Dr. Pongratz, you and your > co-authors did a pretty good job of separating "SRM" from "Geoengineering". > (I don't think the phrase "CDR" appeared, however) This is to again hope that > all authors doing fine work like yours at Carnegie go out of their way to say > that Geoengineering has both SRM and CDR parts. > like > 2. The NPR interview below does not do that at all. Fortunately the other two > ("bitsof science" and "smartplanet") do at least use the terms "SRM" and > "sunshade". All of them fail to mention that CDR is a second (and much less > controversial) part of Geoengineering. > > 3. I mention this mainly because your Carnegie team is (I think correctly) > not arguing for any SRM at this time. However, there are many on this list > who think we are ready now for an accelerated push on CDR. > > 4. I also have hopes that your modeling work can be extended into the CDR > world. We need such modeling - urgently. > > As previously, thanks for alerting us - and (especially) making your Carnegie > papers available - to the list. > > Ron > > > > ----- Original Message ----- > From: "Ken Caldeira" <kcalde...@carnegie.stanford.edu> > To: "geoengineering" <geoengineering@googlegroups.com> > Sent: Tuesday, January 24, 2012 9:59:00 AM > Subject: [geo] Crop yields in a geoengineered climate (notes from the > blogosphere ...) > > Some coverage in the "blogosphere" of our recent paper from Nature Climate > Change (attached): > > http://www.npr.org/blogs/thesalt/2012/01/20/145535536/geoengineered-f... > Geoengineered Food? Climate Fix Could Boost Crop Yields, But With Risks > > For a few years now, a handful of scientists have been proposing grandiose > technological fixes for the world's climate to combat the effects of global > warming — schemes called geoengineering . > > Climate change has the potential to wreak all kinds of havoc on the planet, > including the food system. Scientists predict that two variables farmers > depend on heavily — temperature and precipitation — are already changing and > affecting food production in some arid parts of the world where there isn't a > lot of room for error. And if the problem worsens on a larger scale, it could > do a lot of damage to agricultural yields and food security. > > At some point, governments may decide "to do something desperate to protect > our food and our people," Ken Caldeira , an environmental scientist at > Stanford University, tells The Salt. And that "something desperate" could be > geoengineering. > > One proposal scientists are batting around is to fill the upper atmosphere > with tiny particles that could scatter sunlight before it reaches, and warms, > the Earth's surface. Sulfate droplets inside volcanic ash clouds already do > this naturally. So the idea is that a few million tons of sulfates, sprayed > into the stratosphere by airplanes, could produce the same effect > artificially. > > Scientists have been messing with local weather for decades. China does it > all the time, most infamously during the 2008 Olympics . But around 2006, the > notion of doing it on a global scale got more traction, especially when Nobel > laureate Paul Crutzen got behind it . A backlash ensued, as many pointed out > that tampering with such a complex system was far too risky. > > Caldeira began studying geoengineering with the intent of proving that it's a > bad idea. But his new research suggests that manipulating the climate could > actually produce benefits, at least for food production. For instance: a > study from his lab, published Sunday in Nature Climate Change , compares the > effect on the global food supply of unmitigated global warming versus > geoengineering. > > The result? Crop yields of wheat, rice and corn would actually get a boost > from geoengineering. > > Julia Pongratz , a post-doc researcher, led the study. She used computer > climate models to simulate a doubling of carbon dioxide levels in the > atmosphere. Plants like CO 2 , but the models showed that the resulting > temperature increase would lead to an overall decrease in crop yields. > > When she added the cooling effects of geoengineering, however, the model > showed crop yields increasing as much as 20 percent. Without the stress of > higher temperatures, plants would be able to take full advantage of the extra > CO 2 . > > So, does this mean we should start geoengineering today? > > "Definitely not," Pongratz says. > > For one thing, her simulation only studied the average global temperature – > not the localized effects of geoengineering. Even if the global average > remained the same, some regions might get hotter while others get colder. > That could cause drastic local or regional changes in climate and weather > patterns. > > Also, geoengineering wouldn't prevent other harmful effects of higher CO 2 > levels, such as ocean acidification, she says. > > And both of those problems would threaten local food security, especially in > areas where people already have trouble getting enough to eat. > > Until researchers learn more about the specific consequences of > geoengineering, neither Pongratz nor Caldeira is endorsing the idea. > > "Tinkering with planetary-scale processes is a very risky business, and one > that I think most people would not want to undertake lightly," Caldeira says. > "I think it's the sort of thing that people wouldn't consider unless our > backs are against the wall. > > see also: > > http://www.bitsofscience.org/srm-geoengineering-climate-food-producti...http://www.smartplanet.com/blog/thinking-tech/blocking-the-sun-to-sav... > _______________ > Ken Caldeira > > Carnegie Institution Dept of Global Ecology > 260 Panama Street, Stanford, CA 94305 USA > +1 650 704 7212 > kcalde...@carnegie.stanford.eduhttp://dge.stanford.edu/labs/caldeiralab@kencaldeira > > On Sun, Jan 22, 2012 at 8:09 PM, Ken Caldeira < > kcalde...@carnegie.stanford.edu > wrote: > > While our results indicate that crop yields are likely to increase under > sunshade-geoengineering, as you point out these results are not "guaranteed" > to attain in the real world, especially when we take into consideration > complex and difficult-to-predict sociopolitical feedbacks. > > Because of these uncertainties, while there is potential for risk reduction > we cannot state with confidence that climate risks will be reduced through > such efforts. (For example, what if people respond to sunshade-geoengineering > by increasing CO2 emissions?). > > We can state with confidence that reducing emissions will reduce climate > risk. (Note that we did not state that emissions reduction would reduce > overall risk, as we did not do an economic or sociopolitical analysis.) > > There is an important distinction between the certainty of risk reduction and > the expectation of risk reduction. > > Our study was mostly a climate and crop modeling study, and we did not > venture far into the dark woods of sociopolitical analysis. > > On Sun, Jan 22, 2012 at 4:04 PM, Sam Carana < sam.car...@gmail.com > wrote: > > <blockquote> > Ken, > > I did post this finding > at:http://geo-engineering.blogspot.com/2012/01/crop-yields-in-geoenginee... > > The abstract concludes with: > > "Nevertheless, possible yield losses on the local scale as well as > known and unknown side effects and risks associated with > geoengineering indicate that the most certain way to reduce climate > risks to global food security is to reduce emissions of greenhouse > gases." > > This may give the impression that merely reducing emissions of > greenhouse gases was the lowest-risk scenario. In my view, however, > the lowest-risk scenario is a combination of dramatic emission cuts > and responsible geo-engineering. > > Let me add that these simulations do not guarantee that such crop > yields will indeed be achieved, given the threat that continued > emissions pose to the water supply. Further acceleration of the > melting of glaciers in the Himalaya Tibetan plateau threatens to cause > short-term flooding followed by rapid decrease of the flow of ten of > Asia’s largest river systems that originate there, with more than a > billion people’s livelihoods depending on the continued flow of this > water.http://arctic-news.blogspot.com/p/warming-in-arctic.html > > I must again add my protest against the moderation at the Google > geoengineering group that has previously blocked discussion of this > issue. > > Cheers, > Sam Carana > > On Mon, Jan 23, 2012 at 9:01 AM, Ken Caldeira > < kcalde...@carnegie.stanford.edu > wrote: > > Folks, > > > We had a paper come out in Nature Climate Change today that is likely to be > > of interest to readers of this group. The main conclusion is "We find that > > in our models solar-radiation geoengineering in a high-CO2 climate generally > > causes crop yields to increase, largely because temperature stresses are > > diminished while the benefits of CO2 fertilization are retained." > > > Enjoy, > > > Ken > > >http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate137... > > > J. Pongratz, D. B. Lobell, L. Cao, K. Caldeira, Crop yields in a > > geoengineered climate, Nature Climate Change (2012) doi:10.1038/nclimate1373 > > > Abstract: > > > Crop models predict that recent and future climate change may > > have adverse effects on crop yields. Intentional deflection > > of sunlight away from the Earth could diminish the amount of > > climate change in a high-CO2 world. However, it has been > > suggested that this diminution would come at the cost of > > threatening the food and water supply for billions of people. > > Here, we carry out high-CO2, geoengineering and control > > simulations using two climate models to predict the effects on > > global crop yields. We find that in our models solar-radiation > > geoengineering in a high-CO2 climate generally causes crop > > yields to increase, largely because temperature stresses are > > diminished while the benefits of CO2 fertilization are retained. > > Nevertheless, possible > > ... > > read more »- Hide quoted text - > > - Show quoted text - -- 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.
