Guest essay by Eric Worrall
A study in The Lancet claims that by 2050, climate change could cause 500,000 extra deaths per year, due to reduced food production. However the study is model based – where is the supporting evidence?
The abstract of the study;
Global and regional health effects of future food production under climate change: a modelling study
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.
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.
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.
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.
Oxford Martin Programme on the Future of Food.
Sadly the full study is paywalled, but like a lot of model based studies, in my opinion this one doesn’t pass the smell test.
For starters, global warming, or more likely CO2 greening and improved agricultural techniques, are causing agricultural production to soar. There is no reason to think this trend will end anytime soon.
If substantial global warming occurs, vast regions of Canada, Siberia, Northern Europe, even Greenland, which are currently too cold for reliable grain production, will become more agriculturally viable.
Even if global warming causes an increase in extreme weather (note there are substantial thermodynamic limits to this possibility), the increased land surface available for agriculture, combined with 34 years of genetic research and agricultural science, would surely ensure there was plenty for everyone.
Assuming some staples for whatever reason are no longer viable, genetic engineering will ensure proper nutrition. A lot of work has been performed producing nutrition enhanced crops such as golden rice. There is every reason to think this promising line of research will continue to improve the nutritional content of staple foods.
If all else fails, we could simply grow extra food in storm proof greenhouses. Greenhouses are already used extensively in Northern Europe, to produce year round crops of tomatoes and other vegetables, which require a warm growing environment. In 34 years, even at a modest global annual growth rate of 2%, the global economy will still be almost twice as productive as today’s economy – more than enough spare capacity to produce whatever agricultural infrastructure we need, to ensure food production keeps up with demand.
(1 + 0.02) ^ 34 = 1.96
Finally, there is simple experience. I’ve grown vegetables in Britain, on the cool Southern coast of Australia, and on the edge of the tropics. The occasional severe tropical storm does damage my veggie patch, say by knocking some of the fruit off my pepper plants. Yet the tropics are still far more productive than any other region I’ve tried; despite occasional storm damage, the growing season lasts longer, and produces a much greater quantity of produce, for a given area of land. Tropical land experiences ridiculous plant growth rates – you literally have to mow your lawn every few days at the height of wet season, as soon as you get a break in the rain. If more of the world experiences a tropical climate, simple common sense dictates that more agricultural land will be able to sustain tropical levels of food production.