Our changing climate is increasingly linked to food supply challenges, but experts warn against “single factor” explanations and urge quantifying of uncertainties.

An Argentina-based nongovernmental organization, the Universal Ecological Fund, this past January produced a controversial report, “The Food Gap,” that asserted global temperatures would rise by an astounding 2.4 degrees Celsius (4.3 F) by 2020. Such an increase would result in agriculture prices rising up to 20 percent, and the number of undernourished persons globally increasing as much as 70 percent, the report said.

The study, advised by Osvaldo Canziani, former co-chair of an IPCC group that had helped write the landmark 2007 U.N. climate change report, was picked up by a number of media outlets. It was then criticized by NASA scientist Gavin Schmidt at Real Climate.org — and other scientists also objected — for using dubious assumptions about global temperature increases. (IPCC does not project such a rise until much later this century; its peer-reviewed estimates project rises of roughly 0.2 C per decade.)

Reporter Suzanne Goldberg of the Guardian, in the United Kingdom, quickly documented the whole cascade of questionable information rippling out from the UEF report. “An online news service sponsored by the world’s premier scientific association unwittingly promoted a study making the false claim that catastrophic global warming would occur within nine years,” her story began, pointing to the EurekaAlert! news service popular with science journalists among others and published by the American Association for the Advancement of Science, AAAS.

It was, needless to say, an inauspicious beginning to a year in which the nexus of climate, temperature, weather, and food has increasingly come into focus.

More Climate/Food Supply Links Being Sited

With extreme weather events having hurt some crop production, and with soaring food prices identified as having helped trigger revolution in Tunisia, reported links between climate and a food crisis have become more pronounced in the media. Adverse agricultural effects related to climate change are of potentially vast consequence and moral import: Poorer people in the global southern hemisphere are most likely to bear the severe brunt of any such effects — and the public discourse on the issue has reflected growing concerns.

A brief survey provides a glimpse into some of that discourse as it is playing-out in various media:

  • In a February speech, Christina Figueres, executive secretary of the United Nations Framework Convention on Climate Change, said: “On a global level, increasingly unpredictable weather patterns will lead to falling agricultural production and higher food prices, leading to food insecurity. In Africa, crop yields could decline by as much as 50 percent by 2020. Recent experiences around the world clearly show how such situations can cause political instability and undermine the performance of already fragile states.”
  • In a February blog titled “Soaring Food Prices,” New York Times liberal columnist and economist Paul Krugman wrote: “[I]t sure looks like climate change is a major culprit … [E]xtreme weather elsewhere, which again is the sort of thing you should expect from climate change, has played a role in bad harvest around the world.”
  • In an interview on Bloomberg Television, Sunny Verghese, CEO of global agriculture giant Olam, said: “The fact is that climate around the world is changing and that will cause massive disruptions.”
  • South Korean President Lee Myung-Bak told his advisers in February: “The likelihood of a global food crisis is rising due to climate change. We need to set up national strategies and research to tackle the issue.”
  • In a March piece for the Huffington Post titled “Climate Revolutions,” sustainability consultant Tommy Stadlen wrote: “[L]ike almost every revolution in history, from the French Revolution to the fall of the Soviet Empire, the recent [Arab world] turmoil was catalyzed by skyrocketing food prices. And in a worrying portent of climate change’s capacity to bring chaos, it is a flurry of extreme weather events which has caused this record surge in the price of food staples.”
  • In his recent book Climate Wars, syndicated international affairs columnist Gwynne Dyer states: “It is unlikely … that even the U.S. will still be in the food-exporting business once global heating reaches 2 degrees Celsius [3.6 F]. Except for quite limited surpluses in Russia, Scandinavia and (maybe) Canada, nobody will be exporting food. If you cannot produce enough at home, then our people will just have to starve. This is not just a formula for famine; it is also a formula for war.”

Increased Focus Warranted … But with Care

Asked about the increased public focus on food supplies as an aspect of climate change, David Lobell, an expert on the subject and an environmental scientist at Stanford University, said, “I think the attention is warranted … I think these are issues that are not getting enough attention.”

But with a subject so complex, and with so many variables in play, caution and precision are necessary, especially given the relatively nascent stages of this area of study, experts say.

Lobell’s recent study, “The Poverty Implications of Climate-Induced Crop Yield by 2030,” suggests that food prices are unlikely to be affected much because of climate change in the shorter term. But he and other researchers estimate that food staples could rise 10-60 percent by 2030, under a more extreme scenario with very low crop productivity.

No Single Factor … But ‘Things to Really Worry About’

Lobell, one of 10 lead authors now working on the “Food Production Systems and Food Security” chapter for the IPCC’s upcoming fifth assessment report, scheduled to be released in 2013, adds a note of caution when evaluating the causes of recent food-related events: “Statements that start with climate change are typically on pretty shaky ground.” He said that many of the events of interest are driven by fluctuations in food prices, which themselves are the result of the complex interaction between supply and demand.

10 Lead Authors
Working on Food Security Section
of Next IPCC Assessment

“Anyone saying that a single factor is dominating the food system” is being too simplistic, he told The Yale Forum in a telephone interview.

The key to understanding most climate-agriculture modeling, Lobell said, is keeping in mind that scientists are assuming a baseline where everything else — besides the climate change variable — stays constant. “We know that’s not going to be true,” he said of the stable baseline, but such modeling is crucial in establishing the “things to really worry about.”

The need for significant adaptation of agricultural practices in South Asia and southern Africa — two very food-insecure regions — is one of the issues scientists believe policymakers should, to use Lobell’s phrase, “really worry about.”

Harking Back to 2007 IPCC Assessment

It’s worth recalling IPCC’s 2007 report — as a guide for responsible communications. Its findings include:

  • Increases in regional temperature up to 3º C [5.4 F] may have “small beneficial impacts on major rain-fed crops (maize, wheat, rice) in mid- to high-latitude regions,” but “slight warming in seasonally dry and tropical regions reduces yield.”
  • Global food production may be expected to increase with increases in local average temperature over a range of 1 to 3º C [1.8 to 5.4 F], but to decrease with higher average temperature increases.
  • Climate change may increase the number of undernourished people by up to 170 million, though socioeconomic and development factors are likely to play a much more decisive role.
  • Crop loss due to extreme events, such as heavy rains and flash flooding, and persistent droughts, may become more frequent and may outweigh positive effects of temperature increases.
  • Overall, the impact of climate change on global agriculture “might be small overall in the first half of the 21st century, but progressively negative after that.”

The IPCC report also touched on difficult — and still unresolved — questions over how increased CO2 levels might affect crop yields and said some beneficial effects might be expected. (Lobell said that “more data points in terms of experiments” are being added to the state of scientific knowledge on that issue.)

Quantifying Uncertainties Recommended

An important 2009 paper in the Journal of Experimental Botany, “Crops and Climate Change: Progress, Trends, and Challenges in Simulating Impacts and Informing Adaptation,” surveyed the modeling scientists have been doing and suggested room for improvement, including better quantifying of the uncertainty of impacts. The paper concludes:

There are many complex processes and interactions that determine crop yield under climate change. These include the response of crops to mean temperature, the interaction between water stress and CO2, and the interaction between ozone and a range of variables. As a result of this, and of the importance of scale and geography in determining crop productivity, perhaps the greatest challenge for future syntheses of knowledge on the response of crops to climate change is the balance between generality and specificity in region and scale.

Some other research groups are trying to achieve more specificity about emerging challenges and threats in a warmer climate. The U.S. Department of Agriculture, for example, recently announced it will spend tens of millions on research investigating impacts of climate change on midwestern corn and wheat in the Northwest. (A paper published in the Proceedings of the National Academies of Science projects that U.S. crops could be severely hurt by rising temperatures.)

The International Food Research Policy Institute’s (IFRPI) widely reported 2010 research report furnished a more accelerated timeline for severe impacts than that of IPCC and contended that food prices could spike dramatically by 2050 as a result of climate change. For example, it suggests a possible 130 percent spike in the price of maize in sub-Saharan Africa.

But IFRPI, which painstakingly modeled 15 different scenarios to deal with numerous variables, states at the outset that it “must be emphasized that combined biophysical-socioeconomic modeling of this detail and extent is still in its infancy.”

10 Lead Authors
Working on Food Security Section
of Next IPCC Assessment

1. Pramod Aggarwal, Indian Agricultural Research Institute: p.k.aggarwal@cgiar.org

2. David Lobell, Stanford University: dlobell@stanford.edu

3. John Porter, University of Copenhagen: jrp@life.ku.dk

4. Andrew Challinor, University of Leeds: a.j.challinor@leeds.ac.uk

5. Kevern Cochrane, Food and Agriculture Organization of the United Nations: Kevern.Cochrane@fao.org

6. Mark Howden: mark.howden@csiro.au

7. Muhammad Mohsin Iqbal, Global Change Impact Studies Centre: mohsin.iqbal@gcisc.org.pk

8. Maria Isabel Travasso, Instituto Nacional de Tecnología Agropecuaria: mtravasso@inta.gov.ar

9. Kaija Hakala, MTT Agrifood Research Finland: kaija.hakala@mtt.fi

10. Liyong Zie, Shenyang Agricultural University: Xly0910@syau.edu.cn

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John Wihbey

John Wihbey, a writer, educator, and researcher, is an assistant professor of journalism at Northeastern University and a correspondent for Boston Globe Ideas. Previously, he was an assistant director...