Food Security and Climate Change: How the Composition of Plants could be different in the Future

By Associate Professor Roslyn Gleadow

In order to feed a growing population and support the trend towards a higher meat diet in many parts of the world, food production needs to double by 2050 – using less arable land, less fertilizer, and in a time of uncertain climate change.

While the climate adaptation debate has largely focused on yields, the nutritional quality of food is also fundamental. Future increases in yield must not be achieved at the expense of the nutritive value of food. 

Leaves of plants grown experimentally at elevated CO2 levels almost always have lower concentrations of protein. This decrease in nutritional value of plants in direct response to CO2 is an under-appreciated side effect of atmospheric change.

Another issue is that most plants also contain antinutritional compounds that protect them from herbivores. For the past 16 years we have been studying the effect of elevated CO2 on plants that use toxic cyanide in their arsenal.

Many important crops (e.g. sorghum, cassava, almonds and clover) use cyanide to defend themselves against pests. Cassava is the only crop that is toxic unless it is processed, yet over 500,000,000 people in the world rely on it. Cyanide toxicity from eating poorly processed cassava regularly causes konzo (a type of permanent paralysis), especially in children, and sometimes results in death .

Plants are more efficient when there is more CO2 in the atmosphere, freeing up resources and energy to make more of these defence compounds. This is good for the plants, but not so good for the animals that feed on them, including us.

Plants that are water-stressed are also more toxic, so the likely combination of increased episodic drought and higher atmospheric CO2 in coming decades could lead to a significant increase in cyanide-related diseases.

At this stage it is hard to be very specific about what to expect and how to plan for the future but it is likely that new varieties, or different species, may well need to be planted for use in food production and also for wildlife conservation.

For those living on crops such as cassava, which is already problematic in many countries, improved processing methods will be needed to ensure that more of the cyanide is consistently removed before consumption.

This research was supported by the ARC, Pacific Seeds, AusAID, the Finkel Foundation and Monash University.