Nasa paper in GRL suggesting climate effects of CO2 less drastic than claimed
Richard Harter
don't you know. The essence is that most models do not properly
account for the effects of increased CO2 on plants and that there
would be significant evapotranspiration cooling. I'm hoping that
some of regulars who climate science researchers will comment.
Here is the paper abstract from the Geophysical Research Letters
web site,
http://europa.agu.org/?view=article&uri=/journals/gl/gl1023/2010GL045338/2010GL045338.xml&t=gl,bounoua
Several climate models indicate that in a 2 × CO2 environment,
temperature and precipitation would increase and runoff would
increase faster than precipitation. These models, however, did
not allow the vegetation to increase its leaf density as a
response to the physiological effects of increased CO2 and
consequent changes in climate. Other assessments included these
interactions but did not account for the vegetation
down-regulation to reduce plant's photosynthetic activity and as
such resulted in a weak vegetation negative response. When we
combine these interactions in climate simulations with 2 × CO2,
the associated increase in precipitation contributes primarily to
increase evapotranspiration rather than surface runoff,
consistent with observations, and results in an additional
cooling effect not fully accounted for in previous simulations
with elevated CO2. By accelerating the water cycle, this feedback
slows but does not alleviate the projected warming, reducing the
land surface warming by 0.6°C. Compared to previous studies,
these results imply that long term negative feedback from
CO2-induced increases in vegetation density could reduce
temperature following a stabilization of CO2 concentration.
Mitchell Coffey
> I found a reference to this paper in slashdot - news for nerds,
> don't you know. The essence is that most models do not properly
> account for the effects of increased CO2 on plants and that there
> would be significant evapotranspiration cooling. I'm hoping that
> some of regulars who climate science researchers will comment.
>
> Here is the paper abstract from the Geophysical Research Letters
>
> Several climate models indicate that in a 2 CO2 environment,
> temperature and precipitation would increase and runoff would
> increase faster than precipitation. These models, however, did
> not allow the vegetation to increase its leaf density as a
> response to the physiological effects of increased CO2 and
> consequent changes in climate. Other assessments included these
> interactions but did not account for the vegetation
> down-regulation to reduce plant's photosynthetic activity and as
> such resulted in a weak vegetation negative response. When we
> combine these interactions in climate simulations with 2 CO2,
> the associated increase in precipitation contributes primarily to
> increase evapotranspiration rather than surface runoff,
> consistent with observations, and results in an additional
> cooling effect not fully accounted for in previous simulations
> with elevated CO2. By accelerating the water cycle, this feedback
> slows but does not alleviate the projected warming, reducing the
> land surface warming by 0.6 C. Compared to previous studies,
> these results imply that long term negative feedback from
> CO2-induced increases in vegetation density could reduce
> temperature following a stabilization of CO2 concentration.
Wait - back up: You believe that climate change nonsense?!
Mitchell Coffey
Paul J Gans
>I found a reference to this paper in slashdot - news for nerds,
>don't you know. The essence is that most models do not properly
>account for the effects of increased CO2 on plants and that there
>would be significant evapotranspiration cooling. I'm hoping that
>some of regulars who climate science researchers will comment.
>Here is the paper abstract from the Geophysical Research Letters
>web site,
>http://europa.agu.org/?view=article&uri=/journals/gl/gl1023/2010GL045338/2010GL045338.xml&t=gl,bounoua
>Several climate models indicate that in a 2 ? CO2 environment,
>temperature and precipitation would increase and runoff would
>increase faster than precipitation. These models, however, did
>not allow the vegetation to increase its leaf density as a
>response to the physiological effects of increased CO2 and
>consequent changes in climate. Other assessments included these
>interactions but did not account for the vegetation
>down-regulation to reduce plant's photosynthetic activity and as
>such resulted in a weak vegetation negative response. When we
>combine these interactions in climate simulations with 2 ? CO2,
>the associated increase in precipitation contributes primarily to
>increase evapotranspiration rather than surface runoff,
>consistent with observations, and results in an additional
>cooling effect not fully accounted for in previous simulations
>with elevated CO2. By accelerating the water cycle, this feedback
>slows but does not alleviate the projected warming, reducing the
>land surface warming by 0.6?C. Compared to previous studies,
>these results imply that long term negative feedback from
>CO2-induced increases in vegetation density could reduce
>temperature following a stabilization of CO2 concentration.
I'm not sure I understand this. They are arguing that more
water will evaporate thus absorbing more heat. That's certainly
correct in that if more water evaporates, more heat will be absorbed.
But the water doesn't uusually *stay* evaporated. That releases the
energy absorbed while being evaporated so if all the extra evaporated
water is precipitated, there is no net energy change.
They do seem to be arguing that the extra water would be incorporated
into plants. That's fine, but the heat absorbed will still be released.
If the extra evaporated water stays in the atmosphere which it can
only to a certain extent[1] then one has to deal with the fact that
water is a better greenhouse gas than CO2.
[1] The extent is governed by the fact that evaporated water cannot
increase beyond the limits imposed by the equilibrium between liquid
water (oceans) and water vapor in the atmosphere. That equilibrium
depends only on temperature with the amount of water possible in the
atmosphere increasing (but not dramatically at these temperatures)
with temperature.
--
--- Paul J. Gans
Richard Harter
You are a climate change researcher? I didn't know that. I'm
quite confident your commment contains a comment on the
scientific issues but whatever it might be seems to have escaped
me. BTW, do you contribute regularly to GRL?
Sheesh.
Mitchell Coffey
I don't see that as a denial.
Mitchell Coffey
Ernest Major
<gan...@panix.com> writes
>'m not sure I understand this. They are arguing that more water will
>evaporate thus absorbing more heat. That's certainly correct in that
>if more water evaporates, more heat will be absorbed.
>
>But the water doesn't uusually *stay* evaporated. That releases the
>energy absorbed while being evaporated so if all the extra evaporated
>water is precipitated, there is no net energy change.
Everything else being equal, In the presence of evapotramspiration more
energy is transported from the surface by convection, being deposited in
higher layers of the atmosphere when the water condenses. Therefore
there is less energy to be lost by radiation, so the temperature at
which the surface is in equilibrium is lower.
Heat transport into the atmosphere as latent heat is about 20% of the
amount radiated from the earth's surface.
>
>They do seem to be arguing that the extra water would be incorporated
>into plants. That's fine, but the heat absorbed will still be
>released.
>
>If the extra evaporated water stays in the atmosphere which it can only
>to a certain extent[1] then one has to deal with the fact that water is
>a better greenhouse gas than CO2.
One does wonder why this effect wouldn't dominate. Perhaps if the
increased among of heat transfer by convection is primarily caused by an
increased in the velocity of water in the atmosphere, rather than it's
amount, i.e. more violent and stormy weather.
--
alias Ernest Major
Richard Harter
Nobody says that climate science is simple. :-)
I would like comments from someone who knows a lot more about the
issues than I do. It might be that the absorbed heat goes into
chemical energy - more leaf density means more plant means more
energy locked up in the plants. Whether that works and is
significant is another matter. It is very easy for lay persons
to appreciate the subtle but over arching effects of the details
of plant life on the climate. In any case if evaporation cools
"where does the heat energy go" is the issue.
As a note discussing the effects of water as a green house gas is
tricky because of the cloud cover issue.
As another note, the authors aren't dissing global warming;
rather they are saying that the warm up won't happen as fast as
expected.
Mitchell Coffey
> In message <idr7ij$fl...@reader1.panix.com>, Paul J Gans
Another possibility is that Harter knows something we don't know. 'S
got something up his sleeve, if you know what I mean. Bears watching,
always, that rascal.
Mitchell Coffey
Friar Broccoli
> don't you know. The essence is that most models do not properly
> account for the effects of increased CO2 on plants and that there
> would be significant evapotranspiration cooling. I'm hoping that
> some of regulars who climate science researchers will comment.
>
> Here is the paper abstract from the Geophysical Research Letters
>
> Several climate models indicate that in a 2 CO2 environment,
> temperature and precipitation would increase and runoff would
> increase faster than precipitation. These models, however, did
> not allow the vegetation to increase its leaf density as a
> response to the physiological effects of increased CO2 and
> consequent changes in climate. Other assessments included these
> interactions but did not account for the vegetation
> down-regulation to reduce plant's photosynthetic activity and as
> such resulted in a weak vegetation negative response. When we
> combine these interactions in climate simulations with 2 CO2,
> the associated increase in precipitation contributes primarily to
> increase evapotranspiration rather than surface runoff,
> consistent with observations, and results in an additional
> cooling effect not fully accounted for in previous simulations
> with elevated CO2. By accelerating the water cycle, this feedback
> slows but does not alleviate the projected warming, reducing the
> land surface warming by 0.6 C. Compared to previous studies,
> these results imply that long term negative feedback from
> CO2-induced increases in vegetation density could reduce
> temperature following a stabilization of CO2 concentration.
An effectively opposite view:
http://www.uoguelph.ca/news/2010/10/forests_arent_t.html
el cid
> don't you know. The essence is that most models do not properly
> account for the effects of increased CO2 on plants and that there
> would be significant evapotranspiration cooling. I'm hoping that
> some of regulars who climate science researchers will comment.
>
> Here is the paper abstract from the Geophysical Research Letters
>
I recommend pinging Robert Grumbine or running over to his blog
http://moregrumbinescience.blogspot.com/
I'd call him the talk.origins resident expert but don't know how often
he checks in. He also has a page pointed to some FAQs that
may be of some interest.
http://www.radix.net/~bobg/
Yet you probably already knew all this.
Paul J Gans
I take your points. I'm not sure I totally agree. For instance
high-altitude water can cause a number of effects. I have no idea
which predominate.
We are all aware that climate models don't take every factor into
account. They can't, at least not yet. But all are calibrated
against the past (that's the best that can be done). So some of
the water effects must be taken care of. The details are unknown
to me.
All I was suggesting is that the complications the authors introduce
have many ramifications. One wonders if they've all been taken into
account.
Paul J Gans
I would like expert opinion as well.
The thrust of my comments is that there are many effects and it
may also be that the authors have it backwards... ;-)
Richard Harter
Interesting. Not really relevant, but interesting.
Richard Harter
Just so. I'm not obligated to confirm or deny talk.origins trash
talk.
David Hare-Scott
This was my reaction. Evapotranspriration does not get the heat out of the
system, ie off the earth.
I suspect that it is clumsily worded. Perhaps what was meant was that the
increased carbon cycle will store more carbon in plants and this will lower
atmospheric CO2 which will cause the cooling.
David
el cid
> <gan...@panix.com> writes
> >If the extra evaporated water stays in the atmosphere which it can only
> >to a certain extent[1] then one has to deal with the fact that water is
> >a better greenhouse gas than CO2.
>
> One does wonder why this effect wouldn't dominate. Perhaps if the
> increased among of heat transfer by convection is primarily caused by an
> increased in the velocity of water in the atmosphere, rather than it's
> amount, i.e. more violent and stormy weather.
The effect of water vapor is considered to be a feedback effect
and not a forcing effect. My understanding of the feedback effect
is that a warmer ocean means more evaporation which means
more water vapor but also more clouds with the cloud effect
being significantly cooling so the more water you put up into
the troposphere where it is still cold the more clouds you get
and so put less water up in the troposphere. And more clouds
of course means more precipitation which means less water
water and water vapor in the atmosphere. There are lots and
lots of difficult to compute parameters but there is a system in
place where you can observe the effect. That has been done
and within observable natural temperature variation there's
no runaway tendencies for increased evaporation to lead to more
increased evaporation. Rather, the feedback cycles around
a point established by other factors, like CO2 and solar input.
For much much better explanations, try
http://www.realclimate.org/
And googling water vapor feedback forcing yields plenty of
resources.
I don't know how to put the abstract wording about "accelerating
the water cycle" into this context of if it is meant to be
used in context of run-off versus transpiration with other
implications.
It is perhaps relevant to talk.origins from the perspective of
a further mechanism of homeostasis of a biosphere where
somehow life promotes conditions that support life. Just
don't tell the Gaia people.
William Hyde
I have not seen the paper so I have only a couple of comments.
The first is that at least one of the authors, Piers Sellers, has been
working on vegetation in climate models for decades now, so he clearly
knows more about the subject than I do. That said:
The essence is that most models do not properly
> account for the effects of increased CO2 on plants
I don't think that anybody knows how to properly do this. What
happens in the lab in high-CO2 experiments isn't necessarly what
happens in the field. For example (it isn't the best link, but I've
lost track of the real paper):
http://news.illinois.edu/news/08/0325plantdefense.html
Basically, soybeans raised in high CO2 environments in the lab did
indeed grow faster and larger. But in a high CO2 experiment outdoors
this did not happen to nearly the same extent. The difference is
predation. When chewed upon the plants produce jasmonic acid as part
of a chain which results in toxins being created in the leaves, which
cause the predators to eat less. But high CO2 levels interfered with
jasmonic acid production, so the predators ate their fill, cutting
down on the CO2 fertilization effect. There was no predation in the
original lab experiments, so this effect didn't show up.
There is an interesting evolutionary balance here, as the toxin is
too expensive to produce except when needed, so it is produced only
when it is signalled for. Meantime the bugs can eat a bit of the
toxin (though they live much longer in the lab feasting on toxin-free
leaves) but not much. HIgh CO2 disrupts this balance in favour of the
bugs.
This is only one species of plant, of course, but the point is that we
don't know whether unexpected consequences of this kind will affect
other plants. It seems a bit rash to say that all other plants except
the one studied here will be unaffected. As there are whole biomes
which have not been studied in this way, I don't see how we can model
the overall plant response "properly".
Still, the vegetation model in the paper is doubtless a decent
representation of what we currently know. I just balk at the word
"properly".
and that there
> would be significant evapotranspiration cooling.
I assume that what they mean is that cooling will occur at the
surface, the water will rise high in the atmosphere and give off its
energy as it condenses, and that more of the resulting IR will escape
to space than it would have from the surface. Seems possible but I
would take any quantitative estimates with a grain of salt until this
aspect of the science has developed further.
William Hyde
Desertphile
wrote:
It was a joke.
By the way, 97.6% of climatologists still say humans caused and
arter still causing global climate change.
http://www.pnas.org/content/suppl/2010/06/07/1003187107.DCSupplemental/pnas.201003187SI.pdf
--
http://desertphile.org
Desertphile's Desert Soliloquy. WARNING: view with plenty of water
"Why aren't resurrections from the dead noteworthy?" -- Jim Rutz
"I can't wait till next year when the house starts un funding the EPA!" -- Nutcase in alt.global-warming
Desertphile
<m.co...@starpower.net> wrote:
As Professor Santer pointed out in testimody in front of the USA
congressional hearing on the subject, one must include the effects
of human-produced aerosols (chiefly "black carbon" (soot)) on
plant transpiration. Doing so added about 0.4c to the model, which
=THEN= matched the observed data.
> Wait - back up: You believe that climate change nonsense?!
Good one. But you did not put a "smiley" on it.
> Mitchell Coffey
Desertphile
<eli...@gmail.com> wrote:
> On Dec 9, 11:01 am, c...@tiac.net (Richard Harter) wrote:
The subject "Nasa paper in GRL suggesting climate effects of CO2
less drastic" is not correct. The paper suggests the effects of
atmospheric CO2 on climate may be slower, but just as "drastic" as
otherwise.
Goddard Climate Research found a 5% decrease in global plant
productivity for the past nine years (due to an increase in CO2).
Plant productivity increased regionally, mostly in the northern
hemisphere--- where the most plants are. Globally, the decreases
were greater than the increases.
The abstract from the Geophysical Research Letters (it's still
behind a pay-wall) is only valid if globally plant production
increases with the increasing CO2 in the atmosphere. The opposite
happened from year 2000 to year 2009, and the year 2010 data has
yet to be published (as far as I can find on the 'net). That data
renders the model (above) pointless, since the above model is
predicated upon a global increase in plant productivity due to CO2
increase.
Canada's ground-based tree survey showed a steady slowing of tree
growth as CO2 increased, in the northern hemisphere. The TERRA
satellite shows a decrease in all plant production globally.
One may examine the data:
http://modis.gsfc.nasa.gov/data/dataprod/index.php
Mitchell Coffey
wrote:
Thank you. I hadn't occurred to me that Harter, of all people, would
confuse me for a serious individual.
Mitchell Coffey
Desertphile
> > > Sheesh.
> > It was a joke.
> [snip]
It made me spit up diet orange soda, it was so funny. Just the
"wait - back up" part added 62% of the humor.
> Mitchell Coffey
Richard Harter
<m.co...@starpower.net> wrote:
>On Dec 9, 8:12 pm, Desertphile <desertph...@invalid-address.net>
>wrote:
>> On Thu, 09 Dec 2010 18:46:06 GMT, c...@tiac.net (Richard Harter)
>> wrote:
[snip]
>> > Sheesh.
>>
>> It was a joke.
>[snip]
>
>Thank you. I hadn't occurred to me that Harter, of all people, would
>confuse me for a serious individual.
Oh, I knew it was meant as a joke. I was not amused.
Frank J
'Course not. There's no evidence that the globe is getting warmer. But
there is plenty evidence that human action is the only cause. ;-)
(in case anyone is wondering, that's a jab at deniers who regularly
(always?) confuse GW with anthropogenic GW with "what the govt. must
do about it")
>
> Mitchell Coffey- Hide quoted text -
>
> - Show quoted text -
Steven L.
"Frank J" <fc...@verizon.net> wrote in message
news:82acd998-24b0-4729...@w2g2000yqb.googlegroups.com:
That's because the deniers, who are mostly right of center politically,
have abandoned the field of policy to the left wing.
If they followed Milton Friedman's philosophy and proposed a straight-up
carbon tax, market forces could allocate resources to those goods and
services that produce less CO2. That was what I favored. The public
might buy that over massive Government regulation of the private sector.
But because they just go around insisting that 97% of the world's
scientists are conspiring to hoax the world's population, they have
walked off the field of rational policy, and conceded policy on global
warming to the left wing.
Which they can then attack as "socialism".
-- Steven L.
Desertphile
"Left wing?" LOL! There is no "left wing" making or suggesting
policy in the USA. Not on any subject at all, let alone global
climate change and how to mitigate the effects.
> If they followed Milton Friedman's philosophy and proposed a straight-up
> carbon tax, market forces could allocate resources to those goods and
> services that produce less CO2. That was what I favored. The public
> might buy that over massive Government regulation of the private sector.
That already happened: people prefer automobiles that are more
fuel efficient over others, if and when they can afford it.
Meanwhile CO2 still increases by 2 parts per million per year.
There is only one way to reduce CO2 emissions successfully (i.e.,
economically): reduce the number of humans.
> But because they just go around insisting that 97% of the world's
> scientists are conspiring to hoax the world's population, they have
> walked off the field of rational policy, and conceded policy on global
> warming to the left wing.
By "Left Wing" you actually mean conservatives and moderates.
> Which they can then attack as "socialism".
Pseudoconservatives never need an excuse to attack imaginary
enemies.
Paul J Gans
Walter Bushell
They are proof positive that Satan exists.
--
The Chinese pretend their goods are good and we pretend our money
is good, or is it the reverse?
Mitchell Coffey
C'est la guerre.
Mitchell
Desertphile
<eli...@gmail.com> wrote:
Note that the denialist cult whackjobs have been lying about what
NASA's paper says, falsely claiming NASA says it will take 200
years for the current global temperature anomaly to reach +1.64c
IT IS A LIE. NASA's paper says no such thing.
See for example:
Original paper: "Quantifying the negative feedback of vegetation
to greenhouse warming: A modeling approach" L. Bounoua et al,
Geophysical Research Letters, Dec 2010 (currently behind a
paywall)
See: Contributions to accelerating atmospheric CO2 growth from
economic activity, carbon intensity, and efficiency of natural
sinks -- J. Canadell, Proceedings of the National Academy of
Sciences 2007
See: "Probabilistic Forecast for 21st Century Climate Based on
Uncertainties in Emissions (without Policy) and Climate
Parameters" -- A.P. Sokolov et al, MIT 2009
http://www.nasa.gov/topics/earth/features/cooling-plant-growth.html
Mauna Loa CO2 growth data:
http://www.esrl.noaa.gov/gmd/ccgg/trends/
The hoax exposed:
http://www.youtube.com/watch?v=l3vIWD4tAHc
Dawlish
wrote:
> Desertphile's Desert Soliloquy. WARNING: view with plenty of water
>
> - Show quoted text -
Normal denier's lies and hopeless attempts at spin. Fortunately, no-
one's listening and govenmnets listen to organisations like NASA
instead.
Steven L.
"deser...@invalid-address.net" <deser...@invalid-address.net>
wrote in message news:9orcg6lhfacrt18cg...@4ax.com:
Uh, you need to distinguish what the Left says from what it believes
privately.
In America as in other democracies, politicians and activists are
naturally duplicitous.
Many in the Congressional Progressive Caucus are also members of the
Democratic Socialists of America (DSA), a genuinely socialist group that
favors government control of all production and distribution. (They
even want single-proprietor small businesses like convenience stories
seized and handed over to worker cooperatives.) You can check this out
for yourself on the Internet.
*BUT* this they will never say on CNN or to the New York Times or the
Washington Post. They have to appear reasonably supportive of our
mostly capitalist economy, in order to keep getting re-elected.
So they are real socialists. But they don't advertise it, which is why
you don't hear about it unless you make the effort to investigate them
using the tools now available to you on the Internet.
> > If they followed Milton Friedman's philosophy and proposed a straight-up
> > carbon tax, market forces could allocate resources to those goods and
> > services that produce less CO2. That was what I favored. The public
> > might buy that over massive Government regulation of the private sector.
>
> That already happened: people prefer automobiles that are more
> fuel efficient over others, if and when they can afford it.
> Meanwhile CO2 still increases by 2 parts per million per year.
The differential could be increased by taxation. Plus there needs to be
a comparable differential for electric energy. Utility companies aren't
going to switch to alternative energy as long as coal is so cheap.
> There is only one way to reduce CO2 emissions successfully (i.e.,
> economically): reduce the number of humans.
In the very long run, there is a question of just how many humans the
planet Earth can sustain.
But you don't want to raise that issue today. In the current state of
our civilization, we do population control by war.
A limited nuclear war between India and Pakistan would both reduce world
population AND kick up enough fallout into the stratosphere to
compensate for global warming. But I don't want to recommend that right
now.
-- Steven L.
Steven L.
"Paul J Gans" <gan...@panix.com> wrote in message
news:ie6n68$4ba$2...@reader1.panix.com:
I've always said that the classic sci-fi movie "When Worlds Collide"
should be required viewing for these deniers and their intended
audience.
In that movie, some scientists around the world discover that the Earth
will soon collide with a distant planet heading toward us from outer
space. They propose a very expensive solution: Build space ships to
evacuate the world's population to other planets.
First, the deniers deny that it's happening.
Then, they admit it's happening, but they say that nothing can be done
about it.
Then when this approaching planet is so close that everyone on earth can
see it in the sky with the naked eye--that's when the panic really
starts.
-- Steven L.
Jeffrey Turner
>
> Canada's ground-based tree survey showed a steady slowing of tree
> growth as CO2 increased, in the northern hemisphere. The TERRA
> satellite shows a decrease in all plant production globally.
There's also the issue of borer beetles and other pests extending
their ranges and killing off Canada's boreal forests. (I toyed
with changing that to "boreal arboreal growth.")
> http://terra.nasa.gov/
>
> One may examine the data:
>
> http://modis.gsfc.nasa.gov/data/dataprod/index.php
--Jeff
--
"We can have democracy in this country,
or we can have great wealth concentrated
in the hands of a few, but we can't have both."
--Louis D. Brandeis
Desertphile
> Normal denier's lies and hopeless attempts at spin. Fortunately, no-
> one's listening and govenmnets listen to organisations like NASA
> instead.
The negative feedback suggested is predicated upon increased
global plant production while CO2 "doubles." Unfortunately that
appears to be an unfounded hope, as photosynthesis tends to
decline as CO2 increases.
http://ddr.nal.usda.gov/bitstream/10113/23/1/IND20369883.pdf
http://treephys.oxfordjournals.org/content/15/3/159.abstract
http://www.esajournals.org/doi/abs/10.1890/0012-9658%281998%29079%5B1526%3ATROTPB%5D2.0.CO%3B2?journalCode=ecol
http://www.springerlink.com/index/32370807846477K5.pdf
Lewis Page just took a few numbers and subtracted him, without
caring what the numbers mean.
--
Desertphile
<sdli...@earthlink.net> wrote:
What "left?" We're talking about the United States of America.
> In America as in other democracies, politicians and activists are
> naturally duplicitous.
Of course.
> Many in the Congressional Progressive Caucus are also members of the
> Democratic Socialists of America (DSA), a genuinely socialist group that
> favors government control of all production and distribution. (They
> even want single-proprietor small businesses like convenience stories
> seized and handed over to worker cooperatives.) You can check this out
> for yourself on the Internet.
"According to its website, the CPC advocates "universal access to
affordable, high quality healthcare," fair trade agreements,
living wage laws, the right of all workers to organize into labor
unions and engage in collective bargaining, the abolition of
significant portions of the USA PATRIOT Act, the legalization of
same-sex marriage, US participation in international treaties such
as the climate change related Kyoto Accords strict campaign
finance reform laws, a complete pullout from the war in Iraq, a
crackdown on corporate welfare and influence, an increase in
income tax rates on upper-middle and upper class households, tax
cuts for the poor, and an increase in welfare spending by the
federal government."
Oh, how =DARE= they?!
Robert Grumbine
> I found a reference to this paper in slashdot - news for nerds,
> don't you know. The essence is that most models do not properly
> account for the effects of increased CO2 on plants and that there
> would be significant evapotranspiration cooling. I'm hoping that
> some of regulars who climate science researchers will comment.
>
>
> Here is the paper abstract from the Geophysical Research Letters
> web site,
>
> Several climate models indicate that in a 2 × CO2 environment,
> temperature and precipitation would increase and runoff would
> increase faster than precipitation. These models, however, did
> not allow the vegetation to increase its leaf density as a
> response to the physiological effects of increased CO2 and
> consequent changes in climate. Other assessments included these
> interactions but did not account for the vegetation
> down-regulation to reduce plant's photosynthetic activity and as
> such resulted in a weak vegetation negative response. When we
> combine these interactions in climate simulations with 2 × CO2,
> the associated increase in precipitation contributes primarily to
> increase evapotranspiration rather than surface runoff,
> consistent with observations, and results in an additional
> cooling effect not fully accounted for in previous simulations
> with elevated CO2. By accelerating the water cycle, this feedback
> slows but does not alleviate the projected warming, reducing the
> land surface warming by 0.6°C. Compared to previous studies,
> these results imply that long term negative feedback from
> CO2-induced increases in vegetation density could reduce
> temperature following a stabilization of CO2 concentration.
I'll throw in a few thoughts, though probably none are terribly surprising.
* It's fairly likely that effects of CO2 on plants are modelled poorly in
climate models; afaik, they're typically not modelled at all.
* Plants, period, are not terribly well-modelled in climate models.
(Perhaps more widely than that, but it's climate models I know something
about.)
* CO2 affects more than leaf density. For many plants, it also reduces
their stoma size, and thence evapotranspiration rates. The authors are
certainly more knowledgeable about the state of those researches than I
am. But it's clearly one with chances for missing multiple competing
effects. Early experiments on CO2 fertilization showed substantial effect,
for instance, which later turned out to be limited to earlier parts of
growth, and zeroed or negative if left in a realistic ecosystem. (And
these later results probably got more complex as more experiments were done;
I'm recalling papers from the later 90s.)
* Taking the result as given, it is less pleasant rather than happier.
There's a widespread mistaken idea that the only thing that matters
(to people, to climate, to ecosystems, ...) is global mean surface temperature,
or global land surface temperature. It follows naturally from people
talking about 'global warming'. That's why I've long thought we should
be talking, and questioning, in terms of climate change.
Anyhow, the supression of global land mean _surface_ _temperature_,
from this model experiment, comes at the hand of increased evapotranspiration
-- increased evaporation from the surface (the plants) _and_ increased
precipitation raining the water back down.
So, taking the paper as completely correct, it says things (at the surface)
won't warm up quite as much, and you'll have more thunderstorms (plus
attendant lightning, flash flooding, runoff, erosion, ...)
Not in the abstract, but mandated by the conservation of energy, the
cooling (relative to expectations) of the surface also comes with
a warming of the atmosphere at the cloud level (where the water is
condensing). That will have further effects through the climate system.
What, exactly, I'm not seeing as obvious. But you can't change
the stability of the atmosphere (warming upper levels faster than
lower levels makes the atmosphere more stable, in a vertical convection
sense) without having effects. Maybe the thunderstorms are somewhat
suppressed (thinner clouds)? But then you don't have the enhanced
evapotranspiration cycle (if it's a sufficient supression).
Climate models do not handle thunderstorm-scale weather yet, so deciding
that question takes more creativity, or patience. On the same hand,
though, the models also don't handle ecosystems well yet either.
So I'd say it's interesting, but there are undoubtedly a number of
caveats (from the authors, for a starter), and substantial need for
seeing what the second paper to address the topic finds.
Thanks El Cid for the advertising.
I do normally field questions from the 'question place' posts at my blog
http://moregrumbinescience.blogspot.com/
my web site/faq site is egregiously old, but having addressed fundamentals,
is still pretty useful for starting points:
http://www.radix.net/~bobg/
I've been far less active at the blog than usual, and far less
active in t.o. than usual -- both since breaking my wrist. It's
improving, and in January, I'm expecting to be getting back to more
normal levels of activity. (For t.o., it means I'll probably notice
any thread with a climate-themed subject, and probably read most
posts on it. If a thread drifts in to climate, I may or may not
notice; fair chance I will if any of a fairly large number of people
comment after the drift.)
I'll also mention that my email address is valid, so you (all) can
write me directly. If we haven't corresponded before, it might be
a while before I find your message in my 'default' folder. (procmail
filtering).
--
Robert Grumbine http://moregrumbinescience.blogspot.com/ Science blog
Sagredo (Galileo Galilei) "You present these recondite matters with too much
evidence and ease; this great facility makes them less appreciated than they
would be had they been presented in a more abstruse manner." Two New Sciences