Crop losses to water shortage may exceed those from all other causes combined. If agriculture is to feed the world’s burgeoning population, yields of water-limited crops must be improved substantially. Efforts to accomplish this have concentrated on increasing the fraction of available water that crops transpire and increasing plant water use efficiency(biomass produced per unit of transpiration. These and other components of crop water economy will be affected by anticipated global changes, changes that include correlated increases in both atmospheric carbon dioxide (CO2) concentration and mean temperature.

Yield of water-limited crops is determined by crop water use and plant water use efficiency, each of which will be affected by the anticipated rise in atmospheric carbon dioxide (CO2) concentration and concomitant increase in temperature. At the leaf level, a given proportional increase in CO2 concentration generally elicits a similar relative increase in transpiration efficiency (ratio of net photosynthesis to transpiration). The increase in transpiration efficiency may result both from an increase in photosynthetic rate and a decrease in stomatal – conductance.
Feedbacks involved in scaling from leaf to crop constrain the increase in net carbon gain and reduce the anti-transpiration effect of CO2 enrichment. As a result, the increase in crop water use efficiency at high CO2 typically is less than 75% of that measured at the leaf level. By accelerating crop development and reducing harvest index, higher temperatures often erode yield benefits of improved water use efficiency at high CO2. The fraction of available water that is used by crops could increase with CO2 concentration because of greater root growth and faster canopy closure, but these effects have received scant study. Field experiments indicate that CO2 enrichment will increase crop water use efficiency mainly by increasing photosyn-thesis and growth. Yield should be most responsive to CO2 when temperatures approximate the optimum for crop growth. Elevating CO2 can ameliorate negative effects of above-optimal temperatures, but temperatures near the upper limit for crops will depress yields irrespective of CO2 concentration.

Implications of Atmospheric and Climatic Change for Crop Yield and Water Use Efficiency
H. Wayne Polley*
Published in Crop Sci. 42:131–140 (2002).

Anyway – so you tell me why Louis is wrong then.

Incidentally some dogs will lie anywhere. Louis had been bagging string theory – now he’s quoting a string theorist when it suits him. Oh the sweet smell of hypocrisy. You need to keep check on your character.

Maybe some companies already get it and don’t need pacts to get moving.

http://www.bpalternativenergy.com/liveassets/bp_internet/alternativenergy/index.html

Anyway your Martian CO2 stuff on your blog is idiotic – get back to Warwick’s blog and answer my substantive claims about your rampant dishonesty and total lack of any analysis in your blog. How you passed geology I’ll never know.

You are clueless about what you are talking about. Ask any physics lecturer.

Better still – you explain here now how the greenhouse effect supposedly works .. .. come on – for the readers .. ..

It is getting worse – some greenhouse effect calculations on the climate sceptics group for Martian CO2 are producing numbers which contradict the belief in the greenhouse effect. So far two quite different approaches were adopted, both analyses coming to the same general conclusion. I expect it will appear in Realclimate sometime.

There is a suggestion that the Greenhouse Gas concept itself might be flawed though considering how mainstream that idea is, I doubt anything will change soon. It has reached the status of a core belief so it will be resistant to contradiction.

A major representation of the world’s best scientists through their publishing record in various areas have through the IPCC process produced some very dry indigestible stste of the science information about where increased atmospheric CO2 might be heading. There are unknowns but a fair bit a stake they say – and once you get the CO2 up there you’re practically stuck with it.

You have a current warming trend that the only plausible reason seems to radiative forcing from extra CO2. It ain’t solar.

It’s a very hard call. Humanity is not good at this stuff. We’re not good at managing droughts and climate “problems” that we already have.

If it were myself I would prefer a market mechanism using Asia Partnership technologies, but also make carbon a commodity of value, and set some “realistic” targets to at least rein in growth of CO2 somewhat. I don’t that would ruin the world and make actually increase global domestic product through innovation.

But from where I sit – Kyoto is gone (was never there really and not enough), Asia pact won’t deliver anything more than a better way to burn coal. Public won’t touch nuclear. So CO2 will keep going up.

Incidentally I think the climate scientists now having been mauled as the messenger are giving up and moving to quietly refining the science and working on adaptation. Pessimistic that any reponse will be taken before major climate changes occur and the public want to know “why”.

I enclose some empircal evidence on greenhouse forcing using pyranometers for your perusal.

Radiative forcing – measured at Earth’s surface – corroborate the
increasing greenhouse effect
Rolf Philipona,1 Bruno Du¨rr,1 Christoph Marty,1 Atsumu Ohmura,2 and Martin Wild2
Received 3 October 2003; revised 3 December 2003; accepted 23 December 2003; published 6 February 2004.
[1] The Intergovernmental Panel of Climate Change
(IPCC) confirmed concentrations of atmospheric
greenhouse gases and radiative forcing to increase as a
result of human activities. Nevertheless, changes in
radiative forcing related to increasing greenhouse gas
concentrations could not be experimentally detected at
Earth’s surface so far. Here we show that atmospheric
longwave downward radiation significantly increased
(+5.2(2.2) Wm
2) partly due to increased cloud amount
(+1.0(2.8) Wm
2) over eight years of measurements at eight
radiation stations distributed over the central Alps. Model
calculations show the cloud-free longwave flux increase
(+4.2(1.9) Wm
2) to be in due proportion with temperature
(+0.82(0.41)
C) and absolute humidity (+0.21(0.10) g m
3)
increases, but three times larger than expected from
anthropogenic greenhouse gases. However, after
subtracting for two thirds of temperature and humidity
rises, the increase of cloud-free longwave downward
radiation (+1.8(0.8) Wm
2) remains statistically
significant and demonstrates radiative forcing due to an
enhanced greenhouse effect. INDEX TERMS: 0325
Atmospheric Composition and Structure: Evolution of the
atmosphere; 1610 Global Change: Atmosphere (0315, 0325);
1620 Global Change: Climate dynamics (3309); 1640 Global
Change: Remote sensing; 3359 Meteorology and Atmospheric
Dynamics: Radiative processes. Citation: Philipona, R., B. Du¨rr,
C. Marty, A. Ohmura, and M. Wild (2004), Radiative forcing -
measured at Earth’s surface – corroborate the increasing
greenhouse effect, Geophys. Res. Lett., 31, L03202, doi:10.1029/
2003GL018765.

ALSO

Greenhouse forcing outweighs decreasing solar radiation driving rapid
temperature rise over land
Rolf Philipona and Bruno Du¨rr
Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Davos Dorf, Switzerland
Received 6 July 2004; revised 1 September 2004; accepted 25 October 2004; published 25 November 2004.
[1] Since 1988, surface temperature over land in Europe
increased three times faster than the northern hemisphere
average. Here we contrast surface climatic and radiative
parameters measured in central Europe over different time
periods, including the extreme summer 2003, to pinpoint
the role of individual radiative forcings in temperature
increases. Interestingly, surface solar radiation rather
decreases since 1981. Also, on an annual basis no net
radiative cooling or warming is observed under changing
cloud amounts. However, high correlation (rT = 0.86) to
increasing temperature is found with total heating radiation
at the surface, and very high correlation (rT = 0.98) with
cloud-free longwave downward radiation. Preponderance of
longwave downward radiative forcing suggests rapidly
increasing greenhouse warming, which outweighs the
decreasing solar radiation measured at the surface and
drives rapid temperature increases over land. INDEX
TERMS: 0325 Atmospheric Composition and Structure:
Evolution of the atmosphere; 1610 Global Change: Atmosphere
(0315, 0325); 1620 Global Change: Climate dynamics (3309);
1640 Global Change: Remote sensing. Citation: Philipona, R.,
and B. Du¨rr (2004), Greenhouse forcing outweighs decreasing
solar radiation driving rapid temperature rise over land, Geophys.
Res. Lett., 31, L22208, doi:10.1029/2004GL020937.

AND

Anthropogenic greenhouse forcing and strong water vapor feedback
increase temperature in Europe
Rolf Philipona,1 Bruno Du¨rr,2 Atsumu Ohmura,3 and Christian Ruckstuhl3
Received 25 May 2005; revised 8 July 2005; accepted 17 August 2005; published 8 October 2005.
[1] Europe’s temperature increases considerably faster
than the northern hemisphere average. Detailed month-bymonth
analyses show temperature and humidity changes for
individual months that are similar for all Europe, indicating
large-scale weather patterns uniformly influencing
temperature. However, superimposed to these changes a
strong west-east gradient is observed for all months. The
gradual temperature and humidity increases from west to
east are not related to circulation but must be due to
non-uniform water vapour feedback. Surface radiation
measurements in central Europe manifest anthropogenic
greenhouse forcing and strong water vapor feedback,
enhancing the forcing and temperature rise by about a
factor of three. Solar radiation decreases and changing cloud
amounts show small net radiative effects. However, high
correlation of increasing cloud-free longwave downward
radiation with temperature (r = 0.99) and absolute humidity
(r = 0.89), and high correlation between ERA-40 integrated
water vapor and CRU surface temperature changes (r =
0.84), demonstrates greenhouse forcing with strong water
vapor feedback. Citation: Philipona, R., B. Durr, A. Ohmura,
and C. Ruckstuhl (2005), Anthropogenic greenhouse forcing and
strong water vapor feedback increase temperature in Europe,
Geophys. Res. Lett., 32, L19809, doi:10.1029/2005GL023624.