Food and Greenhouse Gases: Climate change, agricultural production and food demand.

Post written by C.Will

Our recent blogs have been discussing food security, and the role agricultural production has to play in ensuring a sustainable future. Below are two recently published papers that incorporate the effects of climate change into this discussion.

“Climate change effects on agriculture: Economic responses to biophysical shocks”. By Nelson et al. 2013. Published in Proceedings of the National Academy of Sciences (PNAS).

Abstract:

“Agricultural production is sensitive to weather and thus directly affected by climate change. Plausible estimates of these climate change impacts require combined use of climate, crop, and economic models. Results from previous studies vary substantially due to differences in models, scenarios, and data. This paper is part of a collective effort to systematically integrate these three types of models. We focus on the economic component of the assessment, investigating how nine global economic models of agriculture represent endogenous responses to seven standardized climate change scenarios produced by two climate and five crop models. These responses include adjustments in yields, area, consumption, and international trade. We apply biophysical shocks derived from the Intergovernmental Panel on Climate Change’s representative concentration pathway with end-of-century radiative forcing of 8.5 W/m2. The mean biophysical yield effect with no incremental CO2 fertilization is a 17% reduction globally by 2050 relative to a scenario with unchanging climate. Endogenous economic responses reduce yield loss to 11%, increase area of major crops by 11%, and reduce consumption by 3%. Agricultural production, cropland area, trade, and prices show the greatest degree of variability in response to climate change, and consumption the lowest. The sources of these differences include model structure and specification; in particular, model assumptions about ease of land use conversion, intensification, and trade. This study identifies where models disagree on the relative responses to climate shocks and highlights research activities needed to improve the representation of agricultural adaptation responses to climate change.”

“The future of food demand: understanding differences in global economic models”. By Valin et al. 2013. Published in Agricultural Economics.

Abstract:

“Understanding the capacity of agricultural systems to feed the world population under climate change requires projecting future food demand. This article reviews demand modeling approaches from 10 global economic models participating in the Agricultural Model Intercomparison and Improvement Project (AgMIP). We compare food demand projections in 2050 for various regions and agricultural products under harmonized scenarios of socioeconomic development, climate change, and bioenergy expansion. In the reference scenario (SSP2), food demand increases by 59–98% between 2005 and 2050, slightly higher than the most recent FAO projection of 54% from 2005/2007. The range of results is large, in particular for animal calories (between 61% and 144%), caused by differences in demand systems specifications, and in income and price elasticities. The results are more sensitive to socioeconomic assumptions than to climate change or bio-energy scenarios. When considering a world with higher population and lower economic growth (SSP3), consumption per capita drops on average by 9% for crops and 18% for livestock. The maximum effect of climate change on calorie availability is −6% at the global level, and the effect of bio-fuel production on calorie availability is even smaller.”

Food and Greenhouse Gases: An Ominous Future?

Post written by C. Will

In a world increasing in population and wealth, food production needs to be steadily increasing to meet the growing demand. However, a recent study in Nature Communications (discussed here) argues the rate of yield gains in wheat and rice production have plateaued, despite increased investment in R&D and education. Other studies (for example Ray et al. (2013)) have also found evidence that the current yield gain in major crops is insufficient to reach the estimated 60% increase in production required by 2050. If wheat and rice production have approached a yield ceiling it provides an ominous future for food security.

Previous increases in yield gain have been driven by investment in technologies that were largely one-time innovations and cannot be repeated. For example, innovations in genetically modified grains, major investment in irrigation infrastructure and increased use of fertilisers and pesticides saw steady increases in grain production.

Is livestock agriculture also at risk of approaching a yield ceiling?

New Zealand has experienced significant annual increases in livestock productivity for more than 20 years.  As we discussed in a previous post even with existing technology there is room for significant ongoing improvement as less efficient farmers catch up with those who are more efficient. In the short term, constraints on yield per hectare (intensity) are likely to be environmental (water quantity and quality) rather than technological (as noted by the Parliamentary Commissioner for the Environment’s report on water quality). Internationally, the enormous differences in livestock productivity suggested by differences in emissions per unit of output suggest space for considerable yield gains.  

Globally we need to be making all the efficiency gains that we can to resolve the food security problem and New Zealand has an important role to play in this through the livestock sector.

Food Security and Climate Change

A recent article in the Guardian highlights the increasing importance of food trade globally. Of the countries investigated in the study, 66 currently do not produce enough food to feed their people - roughly 16% of the global population. By 2050 the study predicts that over half of the world’s population will rely on imported food – making global food security more reliant on international trade. The predictions do not take into account the impact of climate change on food supply which could exacerbate the situation.

It is now thought that climate change is going to significantly impact our global food system by shifting where food is grown, in what seasons and in what quantities. Including these possibilities into the predictions of global food security is a necessity if we are to think ahead.

A new study in New Zealand is aiming to look into these issues for our own country. The CCII or Climate Change Impacts and Implications for New Zealand study led by NIWA and Landcare Research will explore the consequences of different climate trends for New Zealand so we can better prepare for these coming issues. The study will generate improved climate projections for New Zealand based on the latest global modelling and evaluate key pressures on and responses of five important environments (alpine, hill-country, lowlands, coastal and marine). The study will also explore feedbacks, cumulative impacts and limits at the national level from the interaction of climate, population, land-use change, economic development, and increase the relevance of climate change in decision making processes. The aim of this project focuses on extending New Zealand's foresight into the issues of climate change and how primary industries such as agriculture can respond to these challenges.

Another part of the equation of global food security is that New Zealand is currently a global food producer. If these predictions come to play and the world is significantly dependent on imported food - New Zealand may be a source of those food supplies for other countries. The increase in demand may offset the economic losses resulting from lowered agricultural production from extreme weather events. The potential negative and positive impacts of these shifts in agricultural production show how complex these issues are.

For more information, check out these condensed and interesting resources on what we know in New Zealand about the interactions between climate change and agriculture.