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.
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-food-climate-fix-could-boost-crop-yields-but-with-risks
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-production-4774/
http://www.smartplanet.com/blog/thinking-tech/blocking-the-sun-to-save-the-planet/10004
_______________
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
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-geoengineered-climate.html
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/nclimate1373.html
>
> 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 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.
>
> A press release is available here:
> http://www.eurekalert.org/pub_releases/2012-01/ci-gag012012.php
>
> We also made a couple of YouTube videos:
>
> Crop yields in a geoengineered climate: Dr. Julia Pongratz
>
> http://www.youtube.com/watch?v=fhxzOUQVD38
>
> Crop yields in a geoengineered climate: Ken Caldeira
>
> http://www.youtube.com/watch?v=-0LCXNoIu-c
>
> _______________
> 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
>
> --
> 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 .
</blockquote>
--
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.
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.
