Eike Luedeling

Katherine Jarvis–Shean

Climate change is not a new phenomenon. The Earth has been through Ice Ages and warm spells. However, in most regions, climate conditions have been fairly stable for many centuries, allowing for the evolution and breeding of certain crops and the creation of cropping systems suited to local conditions.

But anthropogenic climate change resulting from increased greenhouse gas emission is changing agricultural production conditions at an unprecedented rate. By all estimates, in the future our planet will, on average, be warmer than at present. Precipitation patterns are likely to change in many regions. Global climate models also predict a higher incidence of weather extremes, such as droughts and heat waves. These changes will affect the distribution of arable land, the distribution of crops, and the means by which those crops are grown. These changes also have implications for our cultural identities, food security, and food production infrastructure.

There may be some positives for food production in certain locations. New crop land might open up in the northern latitudes and at high elevations; higher temperatures might enhance growth rates; and higher atmospheric CO2 concentrations might increase water use efficiency. However, with these positives come negatives as well. In many of the new climatically suitable growing regions, soil conditions are poor. Moreover, many marginal lands, such as parts of the inner Tropics, or the semi-arid regions of Africa or South and Central Asia, might become unsuitable for agricultural use. Because marginal lands are frequently used by the poorer sectors of society, loss of these lands could lead to migrations and famine. The social and economic hardships that climate change might entail for millions of mostly poor farmers around the world are hard to fathom, and have not yet received due attention.

While most lands which are currently arable will remain so, production systems on those lands will have to be adapted to new conditions. For California’s Central Valley, Luedeling et al. (2009) recently looked at likely changes in winter chill, a vital climate signal for many fruit and nut trees, which allow them to overcome their winter dormancy (www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0006166). The projection results suggested that within only a few decades, suitable land for many important tree crops could almost completely disappear in the state. Current infrastructure might also not be adequate for increased irrigation; current cultivars might not grow and yield as vigorously; and current management practices might not be suited to changing plant-pathogen relationships, soil conditions, or pollinator populations. Recent studies indicate that increased atmospheric CO2 might reduce the nutritional value of many crops, thus exacerbating the problems of malnutrition that already affect millions of people today.

Many crops, regardless of styles of cultivation or variety grown, will simply not be adaptable to new conditions in a location where they have historically been produced. This is alarming, because cultural identities and even religious practices have strong foundations in the crops local peoples grow. In the developed world, climate change will require reforming agricultural infrastructure, modifying crop cultivation techniques and technologies, and retraining farmers to use these new technologies. In the developing world, however, systems are not as easily adaptable because of lack of infrastructure, funding, insurance, agricultural extension, and other knowledge-dissemination mechanisms. These regions are thus likely to be much more severely impacted by climate change than the developed world.

The outlook for food production need not be so gloomy if we take action now. The extent of these climate changes is dependent upon the amount of greenhouse gases we emit. Mitigation of those emissions should thus be a high priority. However, we also need to prepare for changes. We need to know more about the effects of environmental stress on plants. Temperature and CO2 dependent growth models exist for some staple crops, such as wheat and corn, and to some extent we are able to predict their future ranges and performance. For these crops, drought and heat tolerance are already among the most important breeding goals.

For most of the roughly 7,000 plant species that are grown for food around the world, however, we have no idea what the impact of climate change may be, and virtually no efforts are being undertaken to adapt these crops to a changing climate. Research is required to adapt food production to climate change, through plant breeding, new management practices, and dissemination of improved germplasm and cultivation techniques.

To make the necessary adjustments and to allocate the resources needed for this unprecedented challenge, it will be crucial to raise public awareness about the likely consequences of climate change on food production and food security. Climate change is not only about rising oceans and drowning polar bears—it is about our ability to feed ourselves.