But there seems to be no signs of a major slowdown despite heat waves of the past 60 years.
![indicator3_2013_ProductionGrain[1]](http://wattsupwiththat.files.wordpress.com/2014/03/indicator3_2013_productiongrain1.png?quality=75)
From the Institute of Physics
Heat waves could significantly reduce crop yields and threaten global food supply if climate change is not tackled and reversed.
This is according to a new study led by researchers at the University of East Anglia and published today, 20 March, in IOP Publishing’s journal Environmental Research Letters, which has, for the first time, estimated the global effects of extreme temperatures and elevated levels of carbon dioxide (CO2) on the production of maize, wheat and soybean.
Earlier studies have found that climate change is projected to reduce maize yields globally by the end of the century under a “business as usual” scenario for future emissions of greenhouse gases; however, this new study shows that the inclusion of the effects of heat waves, which have not been accounted for in previous modelling calculations, could double the losses of the crop.
Lead author of the study Delphine Deryng, from the Tyndall Centre for Climate Change Research at the University of East Anglia, said: “Instances of extreme temperatures, brought about by a large increase in global mean temperature, can be detrimental to crops at any stage of their development, but in particular around anthesis—the flowering period of the plant.
“At this stage, extreme temperatures can lead to reduced pollen sterility and reduced seed set, greatly reducing the crop yield.”
The impacts on wheat and soybean are likely to be less profound, primarily because of the fertilisation effects that elevated levels of CO2 can have on these crops.
In plants, CO2 is central to the process of photosynthesis—the mechanism by which they create food from sunlight, CO2 and water. When there is more CO2 in the atmosphere, the leaves of plants can capture more of it, resulting in an overall increase in the biomass of the plant.
In addition, plants are able to manage their water use much more efficiently in these conditions, resulting in better tolerance to drought episodes. However, it is not clear whether these CO2 fertilisation effects will actually occur in the field owing to interactions with other factors.
If the CO2 fertilisation effects do occur, the researchers found that the yields of wheat and soybean are expected to increase throughout the 21st century under a “business-as-usual” scenario; however, the increases are projected to be significantly offset by the effects of heat waves, as these plants are still vulnerable to the effects of extreme temperatures.
The positive impacts on soybean yield will be offset by 25 per cent and the positive impacts on wheat will be offset by 52 per cent.
The researchers, from the Tyndall Centre for Climate Change Research (University of East Anglia, Norwich), Grantham Research Institute on Climate Change and the Environment (London School of Economics and Political Science, London), and Global Environmental and Climate Change Centre (McGill University, Montreal), arrived at their results using the global crop model PEGASUS to simulate crop yield responses to 72 climate change scenarios spanning the 21st century.
The study also identified particular areas where heat waves are expected to have the largest negative effects on crop yields. Some of the largest affected areas are key for crop production, for example the North American corn belt for maize. When the CO2 fertilisation effects are not taken into account, the researchers found a net decrease in yields in all three crops, intensified by extreme heat stress, for the top-five producing countries of each crop.
“Our results show that maize yields are expected to be negatively affected by climate change, while the impacts on wheat and soybean are generally positive, unless CO2 fertilisation effects have been overestimated,” continued Deryng.
“However, extreme heat stress reinforced by ‘business-as-usual’ reduces the beneficial effects considerably in these two crops. Climate mitigation policy would help reduce risks of serious negative impacts on maize worldwide and reduce risks of extreme heat stress that threaten global crop production.”
From Thursday 20 March, this paper can be downloaded from http://iopscience.iop.org/1748-9326/9/3/034011/article
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Them researchers got to be dumber then a wooden fence post. I guess they grow their crops in a computer funny farm. Any real farmer would tell them that warmer is better! longer growing seasons better! Bull Scat belongs in the field. pg
It’s an uphill climb, but I do try to get my students to take time to read what they just wrote, just to see if they said what they think they said. Somebodies in UEA should have paid more attention to their grade school teachers:
…extreme temperatures can lead to reduced pollen sterility…
These claims leave one with the impression that those making them have never picked up a history book, or worse, they’re in the embrace of some delusional madness that makes them believe that modern society is immune to weather.
Anasazi – all you’ll ever need to know about people, weather, and the consequences of choosing badly where to hang your hat.
“Heat waves could significantly reduce crop yields and threaten global food supply if climate change is not tackled and reversed.”
This is just fear mongering. The negative effect is on corn. US produces 40% of the world’s corn supply and 70% of US corn goes to animal feeds, biofuel, beer and whiskey. Truthfully these scientists should say climate change threatens animal feeds, biofuel, beer and whiskey supply. But that wouldn’t be too scary. BTW the staple foods in most countries are rice and wheat.
another useless prediction to go from printer to bin.
China produces 30% of world’s corn supply and 70% of China corn is for animal feeds too. Maybe if the animals die because of climate change the vegans will rejoice.
All based on the baseless assertion that extreme heat waves will become the norm. Drivel.
UEA – enough said.
How meaningless is this study? I’ve just tried checking the parameters used for Pegasus to see if it uses increasing / changing growth areas coupled with any temperature increases. No luck on that one but going through the PNAS.org study covering ‘Global gridded crop model intercomparison’ the variations between models are quite astounding.
Maize – varies from +38% to -38%
Wheat – varies from +38% to -27%
Rice runs off the scale looking at 100%++ increase to a -19%
Soy – varies from +80%++ to -30%.
(These tables are found on page 15 of the supplementary appendix)
Spreads of output between the models are so vast as to render them meaningless.
I guess that UEA (University for Environmental Activists) which created the Pegasus model is doing its bit to keep the climate change scare alive as part of what appears to be the current and well-orchestrated release of scare stories .
Pause for thought.
Yes they are right.
But the temperature has to go up first.
Over how long?
Then how fast can crops adapt or be adapted?
Work for the Wunderkinds.
There has been no global warming for over 17 years. However since Earth is continuing to recover from an ice age it seems likely global temperatures will continue to eventually rise. Fortunately increased CO2 fertilization will help to mitigate heat sensitivity various plant species may face.
Drought stress in temperate maize germplasm during flowering season is well known.
Both temperate, and sub/tropical maize germplasms are sensitive to drought stress, less so to heat stress during it’s flowering season reducing yield.
If there is increased rainfall associated with globally increased temperatures, much of the heat and drought stress of maize will be mitigated as this is in a large part due to concomitant drought conditions during periods of elevated temperature.
Current research to identify and optimize maize germplasms for use in Sub Saharan Africa, and Asia are under way. In these areas both drought and heat stress are factors. Fortunately there has been some early success in identifying tropical and subtropical maize germplasms (Asian) that are more resistant to heat and drought stress as part of the Heat Tolerant Maize for Asia (HTMA) project. It is likely these strains can be optimized through further breeding programs to produce viable strains of maize useful in a warmer world.
Overall the likelihood of success of mitigation efforts to lower global CO2 for global climate control seem to be essentially nonexistent despite the billions of dollars and undying faith of many. On the other hand, it will be very likely heat stress tolerant, drought tolerant maize germplasms will be available to feed the world, when needed.
Reference: “Breeding for Heat Stress Tolerance in Tropical and Subtropical Maize.” at
https://scisoc.confex.com/crops/2013am/webprogram/Paper78761.html
I would have thought “reduced pollen sterility” would increase crop yields but I shall put that one down to a misquote by the interviewer.
The three real problems with this report are 1) the lack of any definition of “extreme” or a statement of the likelihood of the “extremes” being reached, 2) the fact that their projected climate scenarios still improve crop yields overall and 3) the assumption that, even if the climate does become untenable for these crops where they are now, the farming can not re-locate.
“however, this new study shows that the inclusion of the effects of heat waves, which have not been accounted for in previous modelling calculations, could double the losses of the crop.”
I just cannot get past the obtuseness of these OCD intellectuals, why do they believe everything that comes out of the backside of a computer model? The end of Humanity is truly nigh!
‘extreme temperatures can lead to reduced pollen sterility ‘
Does that make it more fecund?
Can I say speculation? Europeans of the Little Ice Age must have been positively obese with all that famine and failed crops.
Now let’s see the results after the ‘HOTTEST DECADE ON THE RECORD’ and the rapid, alarming rise in temperature since the late 1970s. It’s worse than we thought, it’s all our fault and we must act now!
Since we are allowed speculation here is some more.
And here are some recent observations after all this terrible heat.
It’s getting worse all the time and we are doomed.
Is it also possible that more warmth (as opposed to heatwaves) at higher latitudes will INCREASE global food supply? Canada? I was told that global warming would make itself mostly felt as you headed away from the tropics and towards the poles, and at night. Less frost damage?
Increased heat waves over the Alps could lead to more glacier melt.
Getting hit by a car driving at 170mph will likely kill you.
Can I have my money now?
“Our results show that maize yields are expected to be negatively affected by climate change, while the impacts on wheat and soybean are generally positive, unless CO2 fertilisation effects have been overestimated,” continued Deryng.
So what if CO2 warming effects have been overestimated? Wouldn’t that also invalidate the whole premise?
[sarc]Or did they decided not to consider that possibility because with no warming for 17 years it is obvious that the CO2 warming effects are real and fully understood?[/sarc]
Getting rid of the mindless ethanol mandate in gas entirely would make even more good to global corn supply. The Fischer–Tropsch process is always available to manufacture transportation fuel from abundant coal as needed.
‘according to a new study led by researchers at the University of East Anglia’
That is as likely to encourage you to read further as
‘according to a new study led by researchers at Disneyland ‘
So people who been show to use poor scientific practice , lose data when it suits them and spin for all their worth and who would be out of job without climate ‘doom’ make a wild claim based on a wild guess. Perhaps I have insulted the researches at Disneyland.
“global crop production” “global food supply”
There is no such thing as “global food supply.” Food supply is local to regional. A tomato in Texas is of no value to people in India. We get the same absurd claims for “global water supply.” I see it as collectivist dreams to control all.
Global climate is another collectivist invention. The earth has many climates, not one. “Global climate” means you don’t know what climate is.
There is a way to increase US corn crops.
We reap what we sow. Are the seeds of future starvation being sown now?
We all keep in mind -more or less (?)- parallel charts comparing world temperature anomalies and CO2 levels. Is the equivalent available for food production and agricultural subsidies?
The Institute of Physics you say? Got news for those physicists and aint it about time they began asking the hard questions-
http://quadrant.org.au/opinion/tony-thomas/2014/03/finally-real-climate-science/
Hallelujah! Ring the bells and deck the halls of the AGU
(hat tip Andrew Bolt)
Woops…the APS
Brian hatch says:
March 19, 2014 at 8:08 pm
“Dr hubert lamb of east anglia uni said in the 1970s that the global cooling then happening would cause crop failure and famine. are both right?”
As average temperatures go down the growing belt narrows (in the north it moves south and in the south it moves north) and food production capabilities decline, or so the story went back then.
The reverse should be true if temperatures rise.