Food Supply Worries of an Agricultural Scientist, Part 3: Climate Change

a picture of drought in Java


I’ll come back to the Mycotoxin issue soon.  Instead, I’ll talk today about my serious worries about Climate Change.  

People involved in world agriculture have no patience with the supposed “debate” about climate change.  We are already seeing the effects, and the projections for the future are not encouraging.  The most troubling feature of this phenomenon (and one that occurs even if you don’t believe that it is human-driven) is that we are facing increasing variation in climatic events.  The yearly changes in average temperature or even annual rainfall may not be dramatic, but what we are anticipating is that there will be more extreme weather events.  Climate averages are not what matters for crop production – Variation is.  A few days of intense rain or heat at the wrong time can devastate a crop.  A few weeks of drought can do the same.  A single hail or frost event can make all the difference in what a farmer can harvest.  We have always had those risks for farming and only long term data will demonstrate whether there has been an increasing trend as is predicted.  For instance, It isn’t possible yet to say that the current, extended drought in Australia is caused by elevated greenhouse gasses, but some day we will know whether it was by looking back historically.  Of course that will be too late.  Our actions have to come now.  The other huge threat from climate change is that water supplies will be more limiting in many areas that are irrigated today.  Though that area is much smaller than rain-fed areas, it is very important to the food supply.

Some have predicted that “Global warming” and elevated CO2 will boost crop production in certain areas.  There might be some occasions where higher temperatures will enhance some yields in normally cold areas, but if the warmth comes with other extreme weather events, the benefits will be diminished.  It also turns out that plants can’t really take full advantage of high CO2 levels.  Basically,  there is no real “up-side” of climate change for farming.

Issues Already Upon Us

There are more subtle trends already apparent that represent the effects of climate change on agriculture: shifting pest ranges because of shifts in temperature and rainfall timing.

The geographical range of plant pests is frequently determined by climate.  Northern growing areas have the advantage that many pests cannot survive the winter and can only become a problem by annual migration and new population growth.  This limits their annual impact.  The highly productive potato growing areas in the Pacific Northwest (ID, WA, OR) have not had problems with a particularly nasty pest called the Potato Tuber Moth (Phthorimaea operculella) because until recently, the pest couldn’t “over-winter” there. It was too cold. 


Potato tuber moth damage

Now subtle temperature shifts have allowed this pest to successfully overwinter in the PNW.  The moth lays its eggs on tubers in the ground that are exposed by soil cracks late in the season.  The larvae hatch out during storage and make a real mess of the potato as shown in the image in this post. This pest is now an emerging threat in this major potato production area.  This is just one example of what climate change will mean, but it demonstrates that even subtle shifts in temperature can lead to major problems.

There is another climate change trend that is happening just as predicted. Northern California is getting more of its annual precipitation as Spring rain rather than as winter snowfall in the mountains.  


Symptoms of apple scab

That is bad from a water supply point of view for cities and farmers, but it is also a problem for apple growers.  Apple Scab (Venturia inaequalis) is a severe disease problem for apples, but in the past it has been less of a problem in dry, irrigated, apple growing areas like California and Washington.  In recent years there have been more untimely spring rains that have turned this disease into a real threat for California apple growers.  This has been particularly problematic for Organic growers whose fungicide options (mainly copper compounds) are not very effective against the disease.  Again, this is just one example of the sort of changes to which farmers will need to adapt.

How Will This Play Out?

My prediction is that farmers in the developed world will largely find ways to deal with these new challenges.  There are actually good, safe pesticide options to deal with the shifting pressures from insects and diseases.  There is a GMO potato trait for resistance to the Tuber Moth.  It was originally developed to help third world potato growers, but as I said in an earlier post, it is unlikely to get used in the PNW for less than rational reasons. Late season insecticide sprays will be needed instead.  There are drought tolerant crops (some GMO, some not) that are beginning to be commercialized and these will help reduce the impact of climate variation.  There are highly efficient drip irrigation systems that can help stretch water resources.

I’m not saying that dealing with climate change will be easy for farmers, but I do think that there are adaptations and technologies that will be able to mitigate many climate change effects as long as we do something about overall emissions to head-off the most severe climate change scenarios (it is not obvious that we are that serious. If we do nothing, farmers won’t be able to continue to feed all of us).

 I do expect food prices to rise because of climate change and because of increasing overall global food demand driven by population growth and rising standards-of-living in the developing world.  For we “rich” folks that will not be a huge issue.  For the world’s poor, it is a different story.

The Ethics

What really worries me about Climate Change is that it will have a devastating impact on farm productivity that will hurt the poor people around the world.  Counties that are highly dependent on food imports will see the proportion of their income spent on food increase to unacceptable levels (as in the “preview” we saw in the food commodity price spike of 2007/8).  Beyond imports, much of the world’s population is fed, and will continue to be fed, by local, low-technology, small-holder farming.  This part of the food supply is extremely vulnerable to the impacts of climate change.  I’ve already blogged about the severe ethical implications of efforts to block the introduction of technologies that could change the prospects for some of these farmers.

The Politics

So, climate change is definitely on my “worry list” for the food supply.  I was hopeful that that this issue would be better addressed now that we finally have a President (my favorite candidate by the way) who was quick to understand that climate change is a real problem.   I was also encouraged when Obama promised that he would respect science.   The prominent early actions of the Obama administration have not been all that encouraging in this regard.  They have been initiatives to increase Organic and small farms.  I’m sorry, but as nice as those sound to a city politician, neither of those agendas will help with this very real challenge that we face, and those are farming systems that are, themselves, highly vulnerable to climate change threats.  

Some Hope

I was encouraged to learn last Friday that Obama appointed Dr. Roger Beachy to head the National Institute of Food and Agriculture (NIFA).  In that position he will be in charge of the process of awarding research grants of $160-200 million/year for developing practical and sustainable farming methods and many of those could be improvements for dealing with climate change.   He hopes to expand that to $700 million over the next few year.  I first met Roger in the late 80s when he was a pioneer in the area of virus resistance in crops.  Later he became the director of the Danforth Center which has been instrumental in applying biotechnology advances that help in the Third World.  Their virus resistant Cassava is a prime example.  Dr. Beachy will now enter a complex political environment, but I am optimistic that he will be able to generate some sound policy direction.

I’m not all gloom and doom about this, but Climate Change is still on my “Worry List”  for the food supply.  There is no room for complacency on this issue.


Image of drought in Java from Dmahendra.  Potato tuber moth damage image from INRA.  Apple scab image from the University of Illinois.

Please comment on this site or email me at [email protected].


  1. Steve Savage

    It depends. If the growing season is longer and/or warmer there could be greater production as long as the rainfall pattern is supportive (not too dry or wet). It would; however, require changes in farming practices that entail some investment risk. Does the grower believe the trend enough to plant a longer season hybrid or put down the additional fertilizer to support the higher yield? In marginal growing areas like the ones you mention growers have to be very careful with their spending, so there could be a lag before growers learned to take advantage of this.
    I am trying to strike a balance here. I don’t want people to be afraid, but I also don’t want them to think that everything is fine without a serious investment in innovation. So many people believe that Organic is the answer for a sustainable future and as nice as that sounds, it just isn’t true because that myth is repeated so often

  2. Cat B

    Absolutely excellent article. Especially since we humans have seemingly lost the ability to adapt over long time spans. I would think the agricultural patterns we see globally evolved over centuries to become locally adapted to conditions. (There’s a reason grains are grown in the south and livestock are grazed in the north – to vastly over-simplify). I would suspect Western society has more than likely become overly dependant on technology for advances in ag productivity and become disconnected to the greater ecological and climatic forces at work. Will human hubris win out? I doubt it. (What can we do without European honey bees? Lots. But, not enough to sustain urban Western population densities). Didn’t the Anazazi Indians face this exact issue? Notice, they’re no longer around.

  3. Steve Savage

    Cat B,
    Actually the advances in technology are the best hope for dealing with this. Primitive farming was just that, primitive. The Anasazi didn’t understand soil fertility and simply depleted nutrients until they could no longer survive. Plowing of land has been a destructive force for millenia, but in the past farmers just moved on to new land. Today we have ways to farm that don’t involve plowing so that the soil can build up organic matter and become better over time just as it does in an undisturbed, natural system. Doing that involves a range of technologies. European honey bees are important to us, but we also need to find ways to restore the native pollinators. I think the disconnectedness that exists is that so few people are directly involved in farming. The few who still farm and the technology community that supports them is more in touch with ecological and climatic issues than ever before

  4. justine rose o. domingo

    Actually the advances in technology are the for best hope for dealing with this.Primitive farming was just that,primitive.The Anasazi didnt understand soil fertility ans simply depleted nutrients until they could no longer survive .Plowing of land has been a destructive force for millenia,but the fast farmers just moved on to new land.Today we have ways to farm that dont involve plowing so that the soil can build up norganic matter and become better over time just as it does in an andisturbed , natural system .Doing that involves a range af technologies .European honey bees are importatn to us . but we also need 2 find ways to restore that native in farming. The few who still farm in technology community that supports them is more in touch with ecological and climantic issues than even before.

    thank you.

Leave a Reply

Your email address will not be published. Required fields are marked *