Thanks, Dave, for the careful read and perspectives. I too am somewhat confused by the demarcation that Ken refers to. Isn't the entire field of geoengineering prescriptive and hence not science by Ken's definition? How can the science body IPCC publish numerous prescriptive tomes on CO2 mitigation? Or does science = observations, models, and predictions, and engineering = responses/actions, and hence IPCC is a science + engineering body? I think for anyone to be forced to stay in a particular box is troubling. As a scientist I'm certainly going to speak up if I have prescriptive ideas, as should anyone else. What am I risking by doing this? -Greg ________________________________________ From: geoengineering@googlegroups.com [geoengineering@googlegroups.com] On Behalf Of Hawkins, Dave [dhawk...@nrdc.org] Sent: Saturday, July 23, 2011 9:40 AM To: kcalde...@gmail.com Cc: John Nissen; em...@lewis-brown.net; geo-engineering grp; John Nissen Subject: [geo] Prescriptive statements in scientific papers
Hi Ken, Your prescription that science papers should not include prescriptive statements raises interesting issues. While I agree that it is important to avoid confusion between science-based findings and statements based on values, it seems to me that it is possible to avoid this confusion in a single paper by careful writing that clearly separates the findings components of the paper from any value-infused implications that the authors draw from the findings. To me it seems an unnecessary obstacle to communication to require that values-based statements appear only in a separate publication than the paper containing the science-based findings. Regarding the Hansen paper, he would probably argue that as a technical matter his paper does not breach your rule though. Certainly, the following sentence from the abstract could be interpreted as a prescriptive statement: "Rapid reduction of fossil fuel emissions is required for humanity to succeed in preserving a planet resembling the one on which civilization developed." But it can also be read as a science-based statement; to wit, based on the paleo-climate information presented in the paper, the authors conclude that continued loadings from fossil fuel use are very likely to result in conditions that are outside the envelope of conditions prevalent during the rise of modern human civilizations. One can argue whether the authors have provided adequate support for this statement but that is different than calling it a policy prescription. In the body of the paper, the last page (pasted below) contains essentially all of the statements that veer into prescriptions. But on my inspection at least, the statements mostly boil down to the inclusion of terms that some (not me) might quarrel with: "disastrous," "devastating," "not safe or appropriate," "unwise," and "disaster scenario." I would agree that "appropriate" and "unwise" are values-infused terms, as, arguably, is "safe.". But "disaster" and "devastating" are just as easily understood as descriptive of the changes the authors argue are likely, based on the paleo-climate science discussed in the paper. In any event, the paper is an interesting illumination of the fuzzy nature of the line between science and prescriptive policy pronouncements. David excerpt from Hansen: "Thus burning all or most fossil fuels guarantees tens of meters of sea level rise, as we have shown that the eventual sea level response is about 20 meters of sea level for each degree Celsius of global warming. We suggest that ice sheet disintegration will be a nonlinear process, spurred by an increasing forcing and by amplifying feedbacks, which is better characterized by a doubling time for the rate of mass disintegration, rather than a linear rate of mass change. If the doubling time is as short as a decade, multi-meter sea level rise could occur this century. Observations of mass loss from Greenland and Antarctica are too brief for significant conclusions, but they are not inconsistent with a doubling time of a decade or less. The picture will become clearer as the measurement record lengthens. There are physical constraints and negative feedbacks that may limit nonlinear ice sheet mass loss. An ice sheet sitting primarily on land above sea level, such as most of Greenland, may be limited by the speed at which it can deliver ice to the ocean via outlet glaciers. But much of the West Antarctic ice sheet, resting on bedrock below sea level, is not so constrained. We recognize the negative feedback that comes into play as iceberg discharge reaches a rate that cools the regional ocean surface. But that negative feedback would be cold comfort. High latitude cooling and low latitude warming would drive more powerful mid-latitude cyclonic storms, including more frequent cases of hurricane force winds. Such storms, in combination with rising sea level, would be disastrous for many of the world's great cities and they would be devastating for the world's economic well-being and cultural heritage. "5.3. How much warming is too much? The most substantial political effort to place a limit on global warming has been the European Union's target to keep global temperature from exceeding the preindustrial level by more than 2°C (European Union, 2008). This goal was later reaffirmed (European Union, 2010) and it was endorsed by a group of Nobel Laureates in the Stockholm Memo (2011). However, based on evidence presented in this paper a target of 2°C is not safe or appropriate. Global warming of 2°C would make Earth much warmer than in the Eemian, when sea level was 4-6 meters higher than today. Indeed, with global warming of 2°C Earth would be headed back toward Pliocene-like conditions. Conceivably a 2°C target is based partly on a perception of what is politically realistic, rather than a statement of pure science. In any event, our science analysis suggests that such a target is not only unwise, but likely a disaster scenario. Detailed consideration of targets is beyond the scope of this paper, but we note that our present study is consistent with the "target CO2" analysis of Hansen et al. (2008). Those authors argued that atmospheric CO2 should be rolled back from its present ~390 ppm at least to the level of approximately 350 ppm. With other climate forcings held fixed, CO2 at 350 ppm would restore the planet's energy balance and keep human-made global warming less than 1°C, as we and several colleagues discuss in two papers ("Earth's Energy Imbalance" and "The Case for Young People and Nature") in preparation." Sent from my iPad On Jul 22, 2011, at 11:03 AM, "Ken Caldeira" <kcalde...@gmail.com<mailto:kcalde...@gmail.com>> wrote: Two points: I am not opposed to scientists making prescriptive statements in their roles as citizens. However, I am opposed to prescriptive statements (statements about what we should do) in peer-reviewed scientific papers. I think science is about establishing objective facts about the world. As citizens, we take these facts and our values and make judgments about what we should do. I am 100% in favor of Jim Hansen making prescriptive statements. I would just prefer that he not do it in the context of a peer-reviewed scientific paper. Science cannot tell us what to do. It can give us information which we can use to make decisions. If the science gets mixed up with politics in peer-reviewed scientific publications, I think it ends up weakening the credibility of the entire scientific publication process (since statements whose truth value cannot be empirically established are obviously getting past reviewers). I should say that the worst in this respect are the economists, who insist that they should be regarded as a science while simultaneously trying to tell us what we should be doing. --- On deployment of some sort of solar reflection system: all of our model results indicate that a high co2 world with deflection of some sunlight would be more similar to a low co2 world than is a high co2 world without deflection of sunlight. So, do I think that direct environmental damage from greenhouse gases could be diminished by deploying such a system? Yes, probably although I am not 100% certain of this. Do I think near-term deployment will reduce overall risk and improve long-term well-being? Of this I am less certain, as it is hard to predict the various sociopolitical, as well as environmental, repercussions that might occur. Ken Caldeira <mailto:kcalde...@carnegie.stanford.edu>kcalde...@carnegie.stanford.edu<mailto:kcalde...@carnegie.stanford.edu> +1 650 704 7212 <http://dge.stanford.edu/labs/caldeiralab>http://dge.stanford.edu/labs/caldeiralab Sent from a limited-typing keyboard On Jul 22, 2011, at 16:38, John Nissen <<mailto:johnnissen2...@gmail.com>johnnissen2...@gmail.com<mailto:johnnissen2...@gmail.com>> wrote: Dear Ken, I've already looked at this interesting paper [1], from Jim Hansen and Mikiko Sato - but I'd not read before of his conjecture about rate of ice mass loss doubling per decade, producing many metres of sea level rise this century. But the implication is that the situation can be saved simply by reducing fossil fuel emissions! Is that the prescription that you are complaining about? Wouldn't a well-considered prescription be welcome from somebody as eminent as Prof Hansen? Geoengineering for example! I don't see a way out of our predicament without it. Do you, Ken? Does Hansen accept that 90% sea ice could be gone as soon as at end summer 2016? (BTW, I've another reference to this date we've been arguing about [2].) Hansen seems to dismiss methane as always producing less forcing than CO2: "This sensitivity has the merit that CO2 is the principal GHG forcing and perhaps the only one with good prospects for quantification of its long-term changes." (page 15) However the paper is relevant to the methane issue in several ways. One argument, which I've heard from Jeff Ridley, is that there is no sign of a methane excursion at previous interglacials* such as end-Eemian, when it was hotter, so we don't need to worry about having an excursion now. Hansen shows that it was never hotter than it is now (in Holocene) by more than one degree. Elsewhere Hansen points out that the current rate of global warming is much higher than it has been for millions of years. Andrew Lockley suggests it's higher than even it was at the PETM some 55.8 million years ago, when temperatures rose about 6 C [3]. That rate of change is important, because of methane's short lifetime. The increasing speed of change implied by Hansen's climate sensitivity is thus relevant to methane. A further way that the paper is relevant to methane is because of climate sensitivity to radiative forcing. The paper suggests various alternative values that could be taken - see [1] table 1. If we get over 2 W/m-2 from methane, then that certainly takes us over the danger line of 2 degrees global warming, using his argument. Cheers, John * During the past 800,000 years, methane never rose much above 700 ppb until recently, see [1] figure 2 [1] Full paper <http://arxiv.org/ftp/arxiv/papers/1105/1105.0968.pdf> <http://arxiv.org/ftp/arxiv/papers/1105/1105.0968.pdf> http://arxiv.org/ftp/arxiv/papers/1105/1105.0968.pdf Abstract here: <http://arxiv.org/abs/1105.0968v3><http://arxiv.org/abs/1105.0968v3>http://arxiv.org/abs/1105.0968v3 [2] <http://www.bbc.co.uk/news/science-environment-13002706> <http://www.bbc.co.uk/news/science-environment-13002706> http://www.bbc.co.uk/news/science-environment-13002706 [3] <http://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum> <http://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum> http://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum --- On Thu, Jul 21, 2011 at 11:07 PM, Emily <<mailto:em...@lewis-brown.net><mailto:em...@lewis-brown.net>em...@lewis-brown.net<mailto:em...@lewis-brown.net>> wrote: Hi, here is a recent paper from Jim Hansen,including some figures I've read before, which stunned me: "In the early Pliocene global temperature was no more than 1-2°C warmer than today, yet sea level was 15-25 meters (50-80 feet) higher." best wishes, Emily. *Paleoclimate Implications: Accepted Paper and 'Popular Science'* "Paleoclimate Implications for Human-Made Climate Change" has been reviewed, revised in response to the referee's suggestions, and accepted for publication in "Climate Change at the Eve of the Second Decade of the Century: Inferences from Paleoclimate and Regional Aspects: Proceedings of Milutin Milankovitch 130th Anniversary Symposium" (Eds. A. Berger, F. Mesinger and D Šijački), Springer. This final version has also been published in arXiv:1105.0968v3 [physics.ao-ph] <<http://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=fbefcc8464&e=60a7483168><http://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=fbefcc8464&e=60a7483168>http://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=fbefcc8464&e=60a7483168> A__'popular science' summary <<http://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=d3b93e0894&e=60a7483168><http://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=d3b93e0894&e=60a7483168>http://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=d3b93e0894&e=60a7483168> of the paper, intended for lay audience, is available. Thanks especially to reviewer Dana Royer for helpful comments, foundations and NASA program managers for research support, and a number of people for comments on an early draft of the paper, as delineated in the acknowledgements. Jim Hansen -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to <mailto:geoengineering@googlegroups.com> <mailto:geoengineering@googlegroups.com> geoengineering@googlegroups.com<mailto:geoengineering@googlegroups.com>. To unsubscribe from this group, send email to <mailto:geoengineering%2bunsubscr...@googlegroups.com> <mailto:geoengineering+unsubscr...@googlegroups.com> geoengineering+unsubscr...@googlegroups.com<mailto:geoengineering+unsubscr...@googlegroups.com>. 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