Knowledge for better food systems

Impact of climate change on food production could cause over 500,000 extra deaths in 2050

This study, published in The Lancet, concludes that climate change will have a dampening effect on progress being made to reduce the number of people who are hungry and malnourished. It concludes that climate change will reduce the number of avoided deaths by 529,000 – or, put another way – will be responsible for 529,000 additional and avoidable deaths by 2050.

The study conceptualises the way that climate change affects health through changes in food consumption, and dietary and weight-related risk factors as follows:

Future food production and consumption is expected to increase, driven by population and income growth and mediated by market responses, such as changes in prices and management practices. Meanwhile, climate change leads to changes in temperature and precipitation, which are expected to reduce global crop productivity and, through market responses, lead to changes in management intensity, cropping area, consumption, and international trade. Changes in food availability and consumption affect dietary and weight-related risk factors associated with an increased incidence of non-communicable diseases and mortality, such as low fruit and vegetable consumption, high red meat consumption, and increased bodyweight.

The study links global models that a. model the impacts of climate change on food production, b. simulate market responses to yield changes (price, trade etc.) and c. link changes in food available – including the type of food available – to risk factors for diseases such as heart disease, strokes, diabetes and cancer as well as to malnutrition – in order to calculate impacts.

It finds that in a scenario without climate change, global food availability is projected to increase by 289 kcal per person per day between the years 2010 and 2050 (a 10·3% increase); global fruit and vegetable consumption, net of food waste is projected to increase by 35·8 g per person per day, and global red meat consumption, net of food waste, to increase by 3·9 g per person per day. The increases in food availability and consumption in this reference scenario without climate change result in 1·9 million avoided in 2050 compared with the baseline with 2010 levels of food availability and consumption.

In the scenarios that factor in climate change, a relative reduction is projected of global food availability in 2050 of 99 kcal per person per day (3·2% reduction), of fruit and vegetable consumption by 14·9 g per person per day (4·0% decrease), and of red meat consumption in 2050 of 0·5 g per person per day (0·7% decrease), when compared with the 2050 reference scenario without climate change. This means that climate change reduces the number of avoided deaths by 28%, which is conceived as leading to 529 000 climate-related deaths compared with the reference scenario in 2050. Most climate-related deaths occurred in the low-income and middle-income countries of the Western Pacific region and Southeast Asia.

Globally, the greatest contributors to the climate-related deaths were changes in dietary risk factors, especially fruit and vegetable consumption. The negative health effects associated with reductions in fruit and vegetable consumption led to 534 000 climate-related deaths, which far outweighed the health benefits associated with reductions in consumption of red meat (29 000 avoided deaths). Weight-related changes in the number of deaths were balanced worldwide. Lower caloric availability because of climate change increased the total number of underweight people, which led to 266 000 additional deaths but it also reduced the number of overweight people, which led to 35 000 avoided deaths and the number of obese people, which led to 225 000 avoided deaths, respectively.

The sensitivity analysis undertaken for the study suggests that climate change mitigation could greatly reduce the number of climate-related deaths. However, a negative net effect would remain even in a stringent climate-stabilisation pathway that incorporates negative emissions.

Abstract

Background

One of the most important consequences of climate change could be its effects on agriculture. Although much research has focused on questions of food security, less has been devoted to assessing the wider health impacts of future changes in agricultural production. In this modelling study, we estimate excess mortality attributable to agriculturally mediated changes in dietary and weight-related risk factors by cause of death for 155 world regions in the year 2050.

Methods

For this modelling study, we linked a detailed agricultural modelling framework, the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT), to a comparative risk assessment of changes in fruit and vegetable consumption, red meat consumption, and bodyweight for deaths from coronary heart disease, stroke, cancer, and an aggregate of other causes. We calculated the change in the number of deaths attributable to climate-related changes in weight and diets for the combination of four emissions pathways (a high emissions pathway, two medium emissions pathways, and a low emissions pathway) and three socioeconomic pathways (sustainable development, middle of the road, and more fragmented development), which each included six scenarios with variable climatic inputs.

Findings

The model projects that by 2050, climate change will lead to per-person reductions of 3·2% (SD 0·4%) in global food availability, 4·0% (0·7%) in fruit and vegetable consumption, and 0·7% (0·1%) in red meat consumption. These changes will be associated with 529 000 climate-related deaths worldwide (95% CI 314 000–736 000), representing a 28% (95% CI 26–33) reduction in the number of deaths that would be avoided because of changes in dietary and weight-related risk factors between 2010 and 2050. Twice as many climate-related deaths were associated with reductions in fruit and vegetable consumption than with climate-related increases in the prevalence of underweight, and most climate-related deaths were projected to occur in south and East Asia. Adoption of climate-stabilisation pathways would reduce the number of climate-related deaths by 29–71%, depending on their stringency.

Interpretation

The health effects of climate change from changes in dietary and weight-related risk factors could be substantial, and exceed other climate-related health impacts that have been estimated. Climate change mitigation could prevent many climate-related deaths. Strengthening of public health programmes aimed at preventing and treating diet and weight-related risk factors could be a suitable climate change adaptation strategy.

Citation

Springmann, M., Mason-D’Croz, D., Robinson, S., Garnett, T., Godfray, H. C. J., Gollin, D., Rayner, M., Ballon, P., Scarborough, P., (2016) Global and regional health effects of future food production under climate change: a modelling study. The Lancet, DOI: 10.1016/S0140-6736(15)01156-3

Read the full article here (requires subscription to The Lancet) and see coverage from Science Daily here. See also an article covering the paper in The Guardian. This research has also received some coverage in the BBC radio show Science in Action - click to hear.

Read more in our research library categories primary production agriculture, climate change: impacts and adaptation,  and the keyword categories  hunger, global health, health concerns, GHG impacts and mitigation, production and consumption trends, non-communicable diseases.

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While some of the food system challenges facing humanity are local, in an interconnected world, adopting a global perspective is essential. Many environmental issues, such as climate change, need supranational commitments and action to be addressed effectively. Due to ever increasing global trade flows, prices of commodities are connected through space; a drought in Romania may thus increase the price of wheat in Zimbabwe.

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