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
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