Food Security and Climate Change

The biggest health risk of global climate change will be its impact on food security. Yet climate models don't include all the adverse effects
of climate change on agriculture.

When it comes to food security and climate change, projections are based on models that grossly underestimate the risk of impacts because they leave out about half the adverse effects of climate change, for example:

• extreme weather events such as severe storms, floods, droughts
• sudden temperature changes at crucial stages in plant growth
• increase in weeds and new weeds
• increase in pests and pest resistance
• changes in water resources available for irrigation
• increase in ground level ozone, which is toxic to plants.

The models also fail to consider the additive and synergistic effects of climate change impacts on water, ecosystems, coastlines and health — all of which will negatively impact agriculture and food production.

Furthermore, look at what's predicted to happen to food security even before we reach a temperature increase of 2ºC, the "target" of major governments around the world!

Figure 1: Adapted from NRC/IPCC (2007) chart of global average temperature increase impacts relevant to food security
(from pre-industrial era)

According to the Intergovernmental Panel on Climate Change, or IPCC (2007), with less than a 1.0ºC increase in global average temperature, localized small holders and subsistence farmers, especially those in low-latitude developing nations, will suffer declining crop yields. (It is interesting — and frightening — to note that in these regions, subsistence farming contributes practically all food produced.)

• Above a 1.0ºC increase, huge populations of the most climate change vulnerable will suffer catastrophic crop losses.
• Global food production is at risk at 1.5ºC and can tolerate no more than a 3.0ºC temperature increase.
• At +2.0ºC, all crops in all regions will tip into declining yields.
• At +3.0ºC, all crops in all regions will drop to below the level of production we have been used to.

Figure 2: Section from IPCC (2007) Impact Chart

Note that the food security results given in the IPCC impacts chart are limited to the climate crop model results. Below is the complete IPCC 2007 chart.

Also note, however, that this chart does not include the effects of extreme weather events on agriculture. Nor does it account for interactions amongst the impacts.

Figure 3: IPCC (2007) Impacts Chart, edited to show loss of food security to most vulnerable populations

Below is an IPCC (2007) graphic on extreme weather events, found under "Five Reasons for Concern." Extreme weather events (one of the IPCC's five reasons for concern) will have the single greatest impact on both agriculture and human health.

Figure 4: IPCC (2007) Extreme Weather Events Reason for Concern

The most recent publication on climate change and food security is from the National Research Council (NRC), 2010. In Stabilization Targets for Atmospheric Greenhouse Gas Concentrations, research on food security and climate change is synthesized and explored.

Even in the most highly mechanized agricultural systems, food production is very dependent on weather. Concern about the potential impacts of climate change on food production, and associated effects on food prices and hunger, have existed since the earliest days of climate change research. Although there is still much to learn, several important findings have emerged from over three decades of research....

[S]tudies often do not estimate impacts without adaptation, making it difficult to gauge assumptions. The costs of adaptation are also not considered in these studies, or reflected in price changes.... [M]ost assessments have not adequately quantified sources of uncertainty. Although different climate scenarios are often tested, processes related to crop yield changes and economic adjustments are often implicitly assumed to be perfectly known. An additional source of uncertainty is potential competition with bio-energy crops for suitable land, which could limit the ability of croplands to expand in temperate regions as simulated by most trade models.
— National Research Council, 2010

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The National Research Council's chapter 5 on Food Production, Prices, and Hunger also explains:

• that higher CO2 levels are beneficial for many plants, but the proposed net effect on yields doesn't take into consideration the many adverse impacts of climate change (higher air temperature, less moisture in the soil)
• that crops develop more quickly under warmer temperatures, leading to shorter growing periods and lower yields
• that the magnitude of local warming per degree of global temperature increase is a source of uncertainty in modelling
• that growers might, due to poor understanding, adapt to the changing climate in ways that actually reduce yields
• that "it will be increasingly difficult to generate varieties with a physiology that can withstand extreme heat and drought while still being economically productive"
• that the effects of climate change on livestock, aquaculture, and fisheries must also be considered, and these are multifactorial
• that the implications of climate change on hunger or food insecurity "follow in part from price changes, but also depend critically on how sources of income and other aspects of health are affected by climate"
• that unintended consequences could have huge impacts; for example, "climate-induced changes in the incidence of diarrheal and other diseases [could] inhibit food security by reducing utilization of nutrients in food"

Food insecurity is the single greatest danger of climate change to vulnerable human populations and indeed to all humanity. That is because there are multiple adverse impacts of global warming and climate disruption on agriculture — and all of these impacts will increase as the global temperature increases.

Healthcare professionals are well positioned to keep reminding the global community about the importance of integrated risk assessment when modelling the impacts of climate change on food security.

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