HEAT ON WHEAT: Rising temperatures are depressing yields of wheat, as pictured here, offsetting gains from improved farming practices
Image: Courtesy of AAAS/Science
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The people of the world get 75 percent of their sustenance—either directly, or indirectly as meat—from four crops: maize (corn), wheat, rice and soybeans. The world's rising population—now predicted by the United Nations to reach 10.1 billion by century's end—has been fed thanks to rising yields of all four of these crops during the past century. Humanity's predilection for burning fossil fuels, however, is now contributing to the slowing of such rising yields, cutting harvests of wheat 5.5 percent and maize 3.8 percent from what they could have been since 1980, according to a new analysis of yields.
"On a global scale, we can see pretty clearly significant changes in the weather for most places where we grow crops," explains agricultural scientist David Lobell of Stanford University's Woods Institute for the Environment, who led the analysis published in the May 6 issue of Science. "Those changes are big enough to sum up to pretty big losses for wheat and corn."
Using U.N. Food and Agriculture Organization data going back to 1980 for crop yields in all major crop-growing regions of the world, and pairing that with temperature and precipitation data for their growing seasons, Lobell and his colleagues found that warming temperatures were reducing yields—although changes in precipitation did not appear to be having an effect, yet.
Those temperature changes are the result of increasing concentrations of atmospheric greenhouse gases, such as carbon dioxide (CO2), largely as a result of burning fossil fuels and agricultural practices. But CO2 also helps rice, soybeans and wheat grow. In fact, the researchers suggest the extra CO2 boosted yields for these crops by roughly 3 percent during the period studied. Unfortunately, in the case of wheat, that wasn't enough to overcome the loss in yields resulting from warming temperatures. "Temperature effects are already overriding CO2 effects," Lobell notes.
Of course, this loss of yield translates directly into food prices, which have been rocketing upward in recent months and years. The new analysis suggests that the climate-related yield loss has contributed as much as 18.9 percent to the average price of a given crop during the period of the study. Climate change "is not disastrous but it's a multibillion-dollar-per-year effect already," Lobell says.
More troubling, further climate change is already locked in: Current CO2 levels imply warming of at least another degree Celsius by 2100. That means areas that have not been affected to date, such as the "corn belt" of the U.S., may soon see the same or worse impacts. "No climate change [in the U.S. corn belt] meant productivity improvements all went to increased yields. By contrast, in Europe the improvements [in yield] went to counteracting the effects of higher temperature," says agricultural economist Gerald Nelson of the International Food Policy Research Institute (IFPRI), who was not involved in the study but found it convincing. "We need to think seriously about breeding crops for dealing with higher temperatures."
Already, agricultural companies such as Monsanto are investing in developing such strains for maize and soybeans, but that leaves less profitable wheat and rice at the mercy of shrinking public sector agricultural research budgets. "Working on a trait like drought resistance is more complex than introducing a trait like insect resistance," says plant breeder Robert Reiter, vice president of biotechnology at Monsanto. "We don't have a lot of genes [to work with] that help produce more grain under water stress."
Nevertheless, Monsanto plans to begin field trials of such a hybrid corn next year, and hopes to introduce it for sale as early as 2013. "Our first gene close to commercialization—what it seems to be doing is helping the plant basically maintain more normal metabolic levels as opposed to trying to shut those processes down under stress," Reiter explains. "We may be taking [genetic] leads from corn and putting them into wheat to help it be drought tolerant and high-yielding."
But IFPRI's Nelson also noted that extreme weather at "fragile points" in a crop's growing cycle, such as high temperatures during the few weeks of flowering in maize and rice plants, could have big impacts. "There are these narrow windows where a small spike in temperature can have a big effect…. Agronomists know these sensitivities but they haven't been looking at them in the context of future climate change."
Adapting agriculture to face a hotter—and potentially drier—future has become a necessity. "We're not saying the sky is falling and food is becoming scarcer and scarcer," Lobell adds. "But there's a real drag on food production from climate change already."
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35 Comments
Add CommentWhile not dismissing this report & not having access to its full details, fuel, fertiliser & pesticide prices have also increased during this period resulting in lower applications & less cultivation between crops during early growing periods to suppress weed growth.. Weather variability has a dramatic effect on crop yields. Much greater than temperature changes of a fraction of a degree.
Reply | Report Abuse | Link to thisBlaming climate change on everything makes many of us suspicious. It is the most sure-fire way of getting research funding.
I agree with you, Carlyle, especially if it's true. If it is, we will actually have to DO something about it, oh my!
Reply | Report Abuse | Link to thisSince carbon dioxide has no effect on climate, blaming CO2 for climate change is not logical. How can CO2 affect climate if CO2 already blocks all 15-micron photons?
Reply | Report Abuse | Link to thisOxygen concentration change is the real cause of climate change. A new ice age will begin when oxygen concentration returns to normal. Oxygen blocks short-wavelength sunlight.
Another commercial article from Monsanto to sell GM products. It is not controlling the nature but adapting to it is the answer.
Reply | Report Abuse | Link to this"One has to be pretty detached from reality not to notice the increase in extreme weather events over the last 30 years." - Vendicar
Reply | Report Abuse | Link to thisSo, this is your contribution of scientific data? You have "noticed" and increase in extreme weather events over a 30 year period? Ever heard of the dust bowl (1930-1940) or the Galveston hurricane (1900) or the tornado super outbreak of 1974? After Katrina (2005) we heard the same garbage and heard predictions of massive devastating hurricanes now becoming the norm. Since then, it's been remarkably quiet.
Extreme weather events have always been with us and the variation is mostly random and not attributable to some fraction of a degree increase in average temperature.
I just love the environmental whackoes (VEN DE) that since their 'facts' don't add up they resort immediately to personal name calling.
Reply | Report Abuse | Link to thisI seriously resent the AGW agenda this magazine is constantly pushing despite all the ACTUAL data that can be analyzed showing that variances in climate is a norm.
It is not the small increase in global average temperature that will damage crops. It is the increase in various local temperatures that will do the damage. That local increase could be much higher than the global average temperature increase. The average is calculated from all the local temperatures over places and times on the planet.
Reply | Report Abuse | Link to thisSimilarly the decrease in plant productivity is here reported from a calculation of the whole agricultural production.
It is indeed somewhat early to decide that this is due to locally expressed global warming. But if it turns out to be true I would not be surprised.
Again it is not the singular event that indicates an effect of global warming. Your examples of extreme weather events do not even come close to the really big ones. There was for example an ice age that covered about half of North America with an enormous ice sheet for about 50000 years.
Reply | Report Abuse | Link to thisBut it is true that the frequency of extreme events has increased over the last 30 years or so and it is likely that the frequency will further increase in the coming years.
Eventually more and more people will come to "notice" that increase.
I agree that name calling is uncalled for, pardon the poor pun.
Reply | Report Abuse | Link to thisIn defence of the Scientific American "persons" I do have to point out that they are reporting on an article published in the peer reviewed Science journal. I do not see this as pushing an agenda.
The "actual" data does indeed show that variances in the climate are the norm. I do not think that anybody disagrees with that.
The question is: Are the current changes in the climate normal and natural fluctuations or are they not normal and not natural in the sense that they are happening much faster than is the norm and that this high rate of change is caused by human beings and their activities?
Strange. I recently read another article on the observed increase in worldwide biomass believed to be due to higher levels of CO2. Seems the tropics worldwide, as well as some temperate zones especially in North America, are showing increases in plant growth. I wonder how this same increase in CO2 can be causing less growth in cereals? As Judge Judy would say, 'if it doesn't sound right it probably isn't true'. I suspect there are other causes if this is in fact, factual.
Reply | Report Abuse | Link to thisAh, VD, you are certainly a name calling nut case if there ever was one. Thought you had lurked over to troll some other site. You can commence calling me names now if you want, but I will not respond.
Reply | Report Abuse | Link to thisHere's an interesting twist on global warming:
Reply | Report Abuse | Link to this...[o]ne of the reasons paleontologists today believe one of the reasons dinosaurs grew so large, was that they weren’t cold-blooded like today’s lizards; they were lukewarm-blooded....But another reason for their size may have been the sweltering oxygen-rich environment that came to dominate the dinosaur era; an environment triggered by volcanism....It was global warming gone wild; CO2 levels increased over 500 percent and temperatures soared. In the greenhouse conditions this created, huge tropical forests spread over many of the continents....Many scientists believe that evolving for millions of years, in this warm, oxygen-rich world, allowed the lukewarm-blooded dinosaurs to reach their enormous sizes. Huge dinosaurs may have been a biological response to a volcanically over-active planet....65 million years ago. The planet was lush. Vegetation was thick on the surface. Living things were prospering like never before."
[2007 DVD. How the Earth was Made. London: Pioneer Productions for the History Channel, 55 min., ff., 1 hr., 3 min.]
The current rapid climate change is anthropomorphic in origin. However don't blame it on CO2 emissions, that is totally wrong. For one thing humans pollute the atmosphere with a multitude of gasses that promote warming and are a lot worse than CO2.
Reply | Report Abuse | Link to thisThe principal culprit driving rapid climate change is Homo sapien population levels, that have decimated the biosphere.
Science may create earthworm burgers and fungal food substitutes, but we can not create environment, and that is what we have run out of now.
As I pointed out on another string recently, the best way to turn population growth around involves three main factors.
Reply | Report Abuse | Link to this1/ Womens rights, where they have the right to take contraception, chose their own partner, be educated & not be forced to remain in a union where they are compelled to obey male partners.
2/ A worldwide attack on corruption.
3/ Free trade, where developing countries have tariff free access to sell their goods wherever they can find a market. Much better than aid which mostly feeds the corrupt though some aid of course is good.
These three issues are the greatest causes of preventing developing countries from climbing out of poverty. With greater prosperity, population will stabilise first, then decline as it already has in many developed countries.
When the internal combustion engine was invented, the people in the oil industry went very glad, as formerly there was not use for gasoline, a mandatory byproduct of the crude distillation. Somebody knows which part of the current gasoline production comes from the mandatory output from crude distillation, and which percentage is produced by cracking or other specially devoided procedures ?. If we are consuming an excess of gasoline, perhaps it would be wise applying a tax reduction for low fuel use transport means
Reply | Report Abuse | Link to thisCarlyle: Your 3 points can be condensed into one: Education.
Reply | Report Abuse | Link to thisHowever this is not going to be. Reason: Greed and religion.
So brace yourself for the savagery of a world population fleeing from the most overpopulated parts and not accepting any law or accepted civilised customs as the raving hordes loot, plunder and murder in the name of their gods and cultures.
In Australia we have been coping with these excesses by those forcing themselves on us. Young girls raped by recent African immigrants are marginalised to keep thing looking neat and tidy. Middle east immigrants spit on girls who do not dress to their standards, rape by these people is also high and remains under wraps, their religion tells them the 10 commandments apply only to those of their own religion. The moderates in their groups are asking people of non middle eastern origin to dress modestly, out of consideration of their sensitivities and culture. However they will not accept that they too need to be sensitive to other cultures and values.
Sadly climate disruption is happening much faster than most of us ever anticipated.
Too pessimistic on all fronts. Humanity has survived many crises that were much worse than we face now. Disease, unrelated to climate is our greatest risk. Even the ‘flu epidemic after the first world war killed more people than were killed in the war.
Reply | Report Abuse | Link to thisHopefully modern medical science will prevent a recurrence of such an event.
The wars we see today, tragic as they are, are nothing compared to earlier times.
There will be loss of life from famine, but far fewer die from this cause than in earlier times. Wars over food never wiped out the human race during earlier famines so why would it in the future.
Global warming, whether natural or human induced, could just as easily result in increased agricultural production. After all, the Nile Valley, Greenland & even Central Australia were lush & green with higher rainfall, not less, in warmer times. As was the Sahara.
I do not disagree with you in total however. Religious extremism has always been & remains a problem. Greed? Not so sure. Look at Bill Gates. I would not call him greedy. The greatest philanthropist the world has ever known. There is a limit to how much an individual can personally consume. The remainder of their wealth is rarely just sitting in some bank vault. It is usually working, providing jobs & wealth for others.
Too pessimistic on all fronts. Humanity has survived many crises that were much worse than we face now. Disease, unrelated to climate is our greatest risk. Even the ‘flu epidemic after the first world war killed more people than were killed in the war.
Reply | Report Abuse | Link to thisHopefully modern medical science will prevent a recurrence of such an event.
The wars we see today, tragic as they are, are nothing compared to earlier times.
There will be loss of life from famine, but far fewer die from this cause than in earlier times. Wars over food never wiped out the human race during earlier famines so why would it in the future.
Global warming, whether natural or human induced, could just as easily result in increased agricultural production. After all, the Nile Valley, Greenland & even Central Australia were lush & green with higher rainfall, not less, in warmer times. As was the Sahara.
I do not disagree with you in total however. Religious extremism has always been & remains a problem. Greed? Not so sure. Look at Bill Gates. I would not call him greedy. The greatest philanthropist the world has ever known. There is a limit to how much an individual can personally consume. The remainder of their wealth is rarely just sitting in some bank vault. It is usually working, providing jobs & wealth for others.
Sorry. Double post.
Reply | Report Abuse | Link to thisGreat job regurgitating Monsanto's PR blitz. They want to create a new market for GW-resistant seeds and you do their bidding.
Reply | Report Abuse | Link to thisI also love how, in one paragraph, we go from decreased increase (still a net gain) to "big losses."
People wonder why AGW preachers have no credibility with skeptics, PR BS like this is one reason why.
Scientific earthling: "...don't blame it on CO2 emissions, that is totally wrong. For one thing humans pollute the atmoshere with a multitude of gases that promote warming and are a lot worse then CO2."
Reply | Report Abuse | Link to thisI glad to see that at least you recognise that the current is anthropogenic however you are incorrect about the influence on the warming climate by CO2 being the least effective. Look at the primary gases which have been implicated in global warming. Methane is said to be 20 times as effective as CO2 by a per unit basis, but methane is much less concentrated then CO2 at about 1800 parts per billion where as CO2 is at about 392 parts per million. H2O is also very effective as a greenhouse gas much more then CO2 but the amount in the atmosphere is determined by temperature. CO2 is going up by about 2 parts per milion per year and is has the clearest overall impact on rising temperatures.
Bodhi: Nitrogen fluorides are tens of thousands of times more effective as greenhouse gasses than CO2. We need to recognise this fact as we ramp up production to produce more electronics and flat screens to assist our masturbatory needs.
Reply | Report Abuse | Link to thisCO2 will in time be taken up by photosynthesis, it is very possible that the human race will be extinct by then. This is not my concern. I am concerned that the damage done might be irreversible (NF3 takes us down this path), this would prevent life from re-establishing itself, while our planet would normally be in a position to sustain life. This too, is not a major concern, its just a nice to have wish.
I believe there is no purpose to life, which is the result of natural selection acting in an environment that accidentally permits life, as we know it, to flourish.
Carlyle: Yes humanity has survived, but often just. We lived in balance with the biosphere, we took and gave to the biosphere. Now we take take & take. 6.9G humans exceed all the humans that have been before. The biosphere is out of balance, the ongoing sixth extinction tells us so. Wars, tsunamis, aids nothing is going to restore balance. Those breeding are the least likely to be educated or educate their children. Famine will follow, just read Malthus, he was brilliant considering the era in which he lived. Science stopped the boom bust population cycle, but now it can do no more. We have run out of resources needed by science to do its magic. A lot of the blame can be attributed to charity, they saved the child and bred the rapist, terrorist, thief and murderer.
Reply | Report Abuse | Link to thisLets talk about disease. A pathogen invades a host's body and seeks to reproduce in that environment. This causes discomfort in the host, perhaps pain and illness as well, remember the pathogen needs the host for its survival. Those pathogens that do the most damage to their hosts, kill their hosts and themselves in the process. At the same time some hosts are more resistant to the pathogen and survive, sustaining the pathogen. Natural selection acts to ensure in time hosts that are resistant and pathogens that cause less harm survive. The pathogen becomes a parasite causing little harm.
Every one of us supports at least 10 trillion microscopic lifeforms in and on our body, we can not live without some, at some stage along the evolutionary route many of these must have been pathogens.
Now look at medicine, we created antibiotics to destroy parasites and pathogens, but we have to now take bacterial supplements to replace the necessary one lost to the antibiotics.
It does not end there. The antibiotics are not equally effective against the entire population of the targeted pathogen, some are more resistant, these survive longer and procreate, generating a new generation better able to cope with the antibiotic. Eventually our antibiotics become useless. Its a war, where each develops newer weapons, but there are no winners.
In India Cholera is back totally resistant to all existing antibiotics. So is TB and expect the others to follow.
While there is plenty to be glum about, predictions of imminent human demise from one cause or another are as old as recorded history at least.
Reply | Report Abuse | Link to thisThere are plenty of causes for hope. The total destruction of smallpox shows what can be achieved. I know that equally, ignorance & religion so far has thwarted a similar success with polio but I remain optimistic.
Yes, humans are consuming resources at a frightening rate but vast resources remain. Eventually more & more of the wasteful practices will be phased out. There have been huge advances in energy efficiency but cheap minimally polluting energy remains elusive. That does not mean that it will not be achieved. Practically everything hinges on cheap energy being developed. With cheap energy, deserts can be made to bloom.
I've seen corn crops fail because of low rainfall, but not because the summer was hot. I'll give this as much weight as I give the other drivel that comes from the U. N.
Reply | Report Abuse | Link to thisWell, winds and rain fall where they do because that's where the winds take them. Winds exist because of thermodynamic imbalances. If you think you can change the thermodynamic properties of the planet and not change where the winds blow, you have a bit to learn.
Reply | Report Abuse | Link to thisa) As the concentration increases, the absorption of the bands around 15 microns expands.
Reply | Report Abuse | Link to thisb) At what altitude or partial density of CO2 do you think the atmosphere stops being saturated when the atmospheric concentration is 287 ppm? 450 ppm?
The European cereal growing region is at a higher latitude that the U.S. region. The higher latitudes have undergone the most rapid temperature change. The tropic, which have been already operating at high temperatures, have suffered crop stress from even a small increase of temperature. The U.S. crop growing region, corresponding to southern Europe, the Middle East, northern India and southern Asia, will undergo crop stress as the Earth continues to warm. When this region, particularly the U.S., experiences crop reduction of yield, it will produce a significant increase of price, and a significant decrease in the availability of grain and legumes worldwide.
Reply | Report Abuse | Link to thisVendicar: I normally don't respond to your posts, most are not based on science or rational thought (to my way of thinking). However this time I wish to point out that your brilliant mind does not comprehend my simple rational thoughts. Perhaps they are too simple for you.
Reply | Report Abuse | Link to thisThe amount does not matter, longevity of its existence does, its effect on the ozone layer and all lifeforms we know off is a concern. Oxides of carbon have life-cycles and should life be present are recycled. With nitrogen halides and similar compounds we are trying to ensure life does not re-emerge after the sixth extinction runs its course.
I am looking beyond zero population. I accept the inevitable extinction of our species in the near future (due to overpopulation & destruction of the biosphere). I am not sorry for this loss. Never before has one species been so destructive of all other lifeforms in the history of this planet.
I accept there is no right or wrong; good or evil; or purpose for anything. Things happen according to the existing rules of nature that emerged from the formation of the universe we inhabit. Unthinking, uncaring natural selection drives all changes in lifeforms that inhabit this universe and perhaps others.
Does this study include the recent marginal land put into production as we grow food for fuel? Such land would necessarily drop the average of productivity because it has less productive soil; and requires more irrigation, fertilizer and pesticides.
Reply | Report Abuse | Link to thisAnd current CO2 levels don't 'imply' anything, YOU infer from the data what you are reporting.
And what of the 40 billion pounds of aerosol pollutants emitted by China over the past decade? 10 billion pounds hits North America annually per NASA 2003 data. We know acid air affects crops. Perhaps that's distorting the data?
Any study that suggests a longer growing season will reduce crop yields really has an uphill climb. Was it also an AGW prediction that we should have greater levels of precipitation due to more moisture in the air?
Reply | Report Abuse | Link to thisRainfall, increased CO2 and a longer growing season shoukd all promote higher crop yields, not lower.
This study purports to overthrow the agricultural laws of physics with a temperature dataset of dubious quality.
As a statistician who has used such data, I can tell you that it is extremely easy to engineer the stochastic result you want by leaving out important controls or adding dubious controls.
What I do not see is an accounting for changes in land use and the marginal productivity of agricultural production. As land used for agriculture grows, each incremental piece of land is likely to be less productive, as all of the really good crop land has been taken already. Expanding land use will necessarily lower average yields as less productive land is cultivated.
I don't see any accounting for the growth in organic farming, which reduces yields by 33% or more.
I do not see any accounting for recent limitations on the use of GM crops in areas where thet had been used. This lowers productivity.
Finally, most objective measures say that crop yields have increased over recent decades, not decreased, when controlled for inputs. These are controlled tests in specific cropland set aside for scientific research, with many on each continent (save Antarctica).
This study seeks to overturn all of that with a simplistic UN dataset and a questionable series of heavily adjusted temperature data.
You can color me skeptical. This outcome seems very contrived to please a certain political constituency promoting AGW recitation. It simply violates the very basics of agronomy.
Recent price swings have been caused by currency swings and the distortions caused by ethanol subsidies, which is another factor this study ignores.
This is dubious at best.
You have some correct information, but you are missing some points.
Reply | Report Abuse | Link to thisEvery crop has a sweet spot for temperature and water. Too much rain can drown a cornfield; not enough rain during peak growth times cripples the plants; two weeks of 100+ temps time can substantially reduce yields compared to 4-6 days of 100+. Climate change is all about change, changing how much rain falls when and where, and changing the range of temps takes some areas currently under production out of their sweet spot.
Your suggestion that changing the conditions will increase yields in general assumes that either farmers are stupid and don't know how to optimize their business, or that re-tooling and/or re-locating for what or where things are grown will come at no cost or loss of productivity. Nevermind that a shift of Hadley cells will put some high yield zones out of business altogether with no relocation option.
Over the 10,000 years that man has been sowing cereals, he has probably tried every possible combination of grain and climate over that period. So it is better to geoengineer the ideal climate than to let consumer junkies continue to mess up the good one that we already had. We have proof that the old climate worked well. We have no proof at all that a changed climate will. To see how to inverse climate change, see www.eprida.com.
Reply | Report Abuse | Link to thisReally, Climate Change is about change? That is profound.
Reply | Report Abuse | Link to thisIt is also not science. Find me a period time during which the climate was not changing?
Better yet, disprove the ubiquitous science that says weather patterns are no more erratic than they have been historically?
The problem with your assertion is that there is ZERO support for it in this study. You are simply repeating the misinformation that weather has become more extreme which is a profound lie, yet one which must be proffered without abatement to sustain climate change religion.
It is really pathetic what this clique will do.
I, like many who consider science an important endeavor, am sick and tired of the climate change lobby breeding it's scare tactics into an ever wider scope of which they know nothing.
It is all a funding scam, and just about everyone is onto the game except the true believers who run on faith. That is why I call it a religion.
FYI: You should examine this authors priors before believing this research. He authored an NBER paper that sought to link "Climate Change" in Africa to civil wars. This study was roundly criticized for a plethora of methodological reasons by political scientists who thought is amateurish.
Reply | Report Abuse | Link to thisFurther, the study actually looked at "Global Warming" not increased variation in weather patterns, so it really had zero to do with your Orwellian "Climate Change" anyway. If you are looking at warming, good science says you should call it warming, not a political buzzword.
I don"t seem to find a single study that does not link warming of less than a degree to some massive historical negative outcome. Odd?
It is really quite strange that wherever he looks he sees climate change. Hmmmm.