David, In practice, that is what I do in public talks. I usually spend most of the talk on science and then i announce that i am moving from science to my own personal value-laden opinions and proceed to make a raft of prescriptive statements.
If this is done in a written paper, I could live with that although it still strikes me as a better idea to write two pieces only one of which is published in a journal whose ostensible purpose is to present scientific findings. Ken Caldeira [email protected] +1 650 704 7212 http://dge.stanford.edu/labs/caldeiralab Sent from a limited-typing keyboard On Jul 23, 2011, at 18:40, "Hawkins, Dave" <[email protected]> wrote: > 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" <[email protected]> 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 >> [email protected] >> +1 650 704 7212 >> http://dge.stanford.edu/labs/caldeiralab >> >> Sent from a limited-typing keyboard >> >> On Jul 22, 2011, at 16:38, John Nissen <[email protected]> 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 -- 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.
