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Frequently Asked Questions about climate change and agriculture: Part 5

Posted by Chad Kruger | November 27, 2012

I’ve made it to the fifth and final question.  I’ve been delving into the five most frequently asked questions I receive about climate change and agriculture over the past several months, and I personally think this last one is the most interesting and possibly the most important. The question is: Will climate change lead to a food system collapse?  It is also the question that we have the least scientific certainty about because it involves projecting forward into the future regarding both the climatic system and human responses. I published an article describing our early research assessing the impacts of climate change on PNW agriculture in Rural Connections last year. I also recently presented a webinar on this topic relevant to Pacific Northwest Agriculture with some of our latest research results. In this post I will highlight the limited available science on the question and identify the critical issues from a more global perspective.

The underlying concern behind this question is that modern agriculture has evolved over the past 100 years under a fairly stable climatic system, and disruption of that stability may create more new challenges than we can readily manage or adapt to. The climatic changes we are mostly concerned about include, but are not limited to, temperature (growing season length, daily averages, trends, extremes, freezes, frosts), precipitation (amount, timing, intensity), consequent impacts on water resources, atmospheric CO2 levels (which acts as a fertilizer for plant growth), climate-driven incidences of weed, disease and insect pests, and even global impacts on competitive markets. If climatic changes occur more rapidly than we can manage or adapt to, it will pose serious threats to our capabilities to feed a growing global population (Smith et al., 2007).

So what does the available science tell us?

The first finding that is generalizable from the scientific literature is that climatic impacts on crop yields are likely to be less severe as latitude increases, with the most negative impacts in the tropical and subtropical regions while the northernmost latitudes may see yield increases (Rosenzweig and Parry, 1994; Parry et al., 2004; Parry et al., 2005; Schlenker and Roberts, 2009).

A related issue is that the type of crop matters a great deal due to how the plant utilizes CO2 for photosynthesis. We know that wheat (and most “cool climate” crops) will likely receive a compensatory “yield boost” from elevated atmospheric CO2 levels that offsets much of the negative affect of warming, while corn (and many of the highly productive “warm climate” crops) will not.

The second major set of findings involves “plant protection” – i.e. keeping the weeds, diseases, and insects from destroying the crop. While this type of study is very cropping-system- and pest-specific, generally speaking scientists project that protecting crops will become more challenging in most places in the future, requiring more knowledge of pest management, more financial investment for control, and new pest management technology and strategies.

The third major set of findings relates to what we already know to be a critical challenge of adapting to a changing climate — that our natural water reservoirs of mountain snowpack are likely to decrease, reducing the security of irrigation water for those regions that currently depend on it. This is an especially challenging problem we face in most arid regions of the world like the Western US. In the Columbia River Basin, for example, we just completed a 20 year projection on the impact of climate change on agricultural water resources.

While there is a significant amount of scientific uncertainty in available projections, most of this science indicates that the types of long-term changes in climatic trends we are likely to see in temperate region agriculture are within the range of changes that the region can manage or adapt to. However, these studies all indicate that our ability to manage these changes depend on a number of caveats – not the least of which is that we plan and invest in adaptation strategies and technologies.

We know that certain adaptations are simply a matter of adjusting management practices that are well-within the current capabilities of farmers and ranchers (e.g. planting seeds earlier), but that more fundamental changes (e.g. variety development, water supply infrastructure, pest management) are dependent on a combination of public and private investment in research, development, commercialization and infrastructure. While the recent trend around the world has been a public dis-investment in agricultural research and infrastructure, there is reason to hope that as more people are informed of the risks of climate change impacts on agriculture and food security that at least the developed countries will make the necessary investments to secure a sustainable food system in a changing climate.

However, in my mind, there are two bigger remaining questions: 1) what is the relative importance of potential changes in extreme events (for which we currently have very little scientific projection, compared to changes in climatic averages), and 2) will the tropical and subtropical regions of the developing world be able to adapt to currently projected changes when they are already plagued by many other challenges? This region is likely to experience more devastating impacts and have fewer resources to invest in adaptation.

In conclusion, I don’t think that the available scientific literature supports the premise that climate change will lead to a global food system collapse. However, I think Stella Coakley and her co-authors probably said it best more than a decade ago: “climate change will add another layer of complexity and uncertainty onto a system [agriculture] that is already exceedingly difficult to manage on a sustainable basis.”