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GEOPHYSICAL RESEARCH LETTERS, VOL. 37, L02704, doi:10.1029/2009GL041662, 2010
Changing links between South Asian summer monsoon circulation and tropospheric land-sea thermal contrasts under a warming scenario
Ying Sun and Yihui Ding
National Climate Center,
China Meteorological Administration,
Beijing, China
National Center for
Atmospheric Research,
Boulder, Colorado,
USA
[1] Forced with
increased greenhouse gases, the South Asian summer monsoon (SASM)
circulation weakens in climate models, which appears inconsistent with
the projected increases in near-surface land-sea thermal contrasts
during the 21st century. Our analysis shows that the SASM intensity
positively correlates with the land-sea thermal contrast in both the
lower- and upper-troposphere before year 2000; thereafter a reduced
upper-tropospheric thermal contrast leads to a weakened SASM
circulation, despite an increasing lower-tropospheric thermal contrast.
The decrease in the upper-tropospheric thermal contrast mainly results
from enhanced upper-tropospheric warming over the tropical Indian Ocean
due to increased latent heating. The results suggest a crucial role of
enhanced tropical convection in the weakening of SASM circulation and a
weak influence of lower-tropospheric thermal contrast on the SASM under
global warming. They also imply a less important role of near-surface
processes over the Tibetan Plateau in the long-term SASM change during
the 21st century.
Last paragraph from th conclusion,
" Because the enhanced upper-tropospheric warming results primarily
from
increased latent heating from tropical convection, this study implies a
crucial role of increased water vapor in SASM’s response to increased
GHGs. Furthermore, despite the weakened monsoon winds, summer monsoon
precipitation in South Asia still increases in most GCMs because of the
increased water vapor content and convergence over the SASM region
[e.g., Ueda
et al., 2006].
Therefore, in the selected seven AR4 models both the increased monsoon
precipitation and the decreased monsoon winds in South Asia are mainly
caused by the increased water vapor and enhanced tropical convection in
a GHG-induced warmer climate."
Received 4 November 2009;
revised 2 December 2009; accepted 15 December 2009; published 21
January 2010.
Sincerely,
Oliver Wingenter
2- Besides, I just don't see the technology "failing". i.e. in that
it might work effectively for a period of time and then somehow we
might not be able to perform it. The only case i can see this
likelihood is in the event that our world returns to some kind of
feudal state-- i.e. collapse. (a reasonably high probability, but in
which case we've all got bigger problems.) But if we're able to
succeed with some method of delivery, such that it "works" (i.e.
global temperatures begin to fall), isn't it likely that we'd be able
to continue what amounts to a pretty low-tech operation into the
future? What is the imagined scenario in which we would not? This is
stipulated, but I don't think defensible. In the movie "Contact" one
unit fails, but we built a second one. It seems reasonable to me that
we would have duplicate or triplicate systems, or even a fully
distributed infrastructure if this was indeed essential for humanity.
3- Your alternative suggestion seems to be, let the methane be
released, we'll capture it. I think this is naive, and essentially
impossible. What is going to be your % effectiveness at capturing
what amounts to trillions of tons of CO2 leaking out from every pore
of the previously frozen north? Not 100%, and probably not even 10%.
But even if by benefit of some extraordinary and (currently unknown
technique) you're somehow 80% effective, we're still pushed way into
the red.
4- Ocean pipes. Assuming the basic technology works-- i.e. that you
can tune the length of the tube to select for more nutrient than the
CO2 you're also bringing up from depth, which the evidence says you
probably can't-- you would still need 10s of thousands--probably
more-- of these units deployed globally. These would either drift
lagrangian stye-- in which case they would tend to accumulate, and
would need to be redeployed-- or as phil kithil suggests, they would
need to be moored and guy-wired together under the sea such that they
maintain adequate distance from each other. This is such a far-
fetched notion as to be essentially preposterous. How would fishing
operations happen with so many fixed devices, what about fouling,
serviceability? What about current shear across the depth of them,
etc etc. Dave Karl and Ricardo Letelier's recent tests were
admirable but revealed a host of issues-- and they were really only
interested in their ability to produce localized phytoplankton blooms
which could be more easily studied for their biological properties.
So, not only does the technology most likely fail on a net carbon
reduction basis, but it most likely fails on a practical and
operational basis as well-- not to mention the unknown effects of
influencing ocean mixing and temperature on that scale. I have yet to
see any thoughtful engineering proposals to the contrary. Just a lot
of arm waving.
5- LCA means Life Cycle Assessment or Analysis. Look it up. It's
become quite sophisticated, with open source input-output tables for
all kinds of manufactured goods and materials available from many
places. It is part of the design requirement for any mature carbon
technology, eg. under the most basic UNFCCC methodological
submission. Simply, it means you have to account for the energy,
carbon, water and overall cost etc. from the full lifecycle process of
all materials, fabrication, installation, operation, servicing,
consumables, water, carbon, and eventual recycling, etc. in order to
demonstrate that what you're doing is any better than the baseline
case (i.e. doing nothing).
Cheers,
Dan
On Feb 3, 1:11 am, Andrew Lockley <andrew.lock...@gmail.com> wrote:
> Thanks Dan.
>
> I don't fully agree with all you've written, and I'll set out why.
>
> As I said before, I'm worried by SRM. Any failure of the technology could
> lead to sudden methane excursions. CO2 air-capture does not have this
> issue.
>
> These methane technologies would, in many cases, be available as a standby
> in the event of future excursions over the next 50 years. Assuming large
> renewable capacity by this time does not seem unreasonable.
>
> I'm not sure I fully understand your concerns regarding logistics of ocean
> pipes. Could you be more specific about the problem you expect?
>
> I think the rankings may indeed be unhelpful, and I'd be interested to hear
> other views on whether they should be removed, rather than revised.
>
> As regards the NOx idea, I don't understand what you mean by LCA. The
> reference for this approach is:
> Wild, O.; Prather, M. J.; Akimoto, H. (2001). "Indirect long‐term global
> radiative cooling from NOxEmissions". *Geophysical Research Letters* *28*:
> 1719.doi <http://en.wikipedia.org/wiki/Digital_object_identifier>:
> 10.1029/2000GL012573 <http://dx.doi.org/10.1029%2F2000GL012573>.
> <http://en.wikipedia.org/w/index.php?title=Template:Cite_doi/10.1029.2...>
>
> I really hope you can continue to comment on this draft paper, as your
> feedback is very helpful.
>
> Thanks!
>
> A
>
> ...
>
> read more »