In 2011 the American Geophysical Union formed a task force to explore concepts for new scientific journals. Among the subject areas the task force identified was a large and important one: the future of our planet.
The union's open-access journal Earth's Future duly made its debut on 5 December 2013. An editorial by Guy Brasseur and Ben van der Pluijm in the first issue set out the new journal's scope and ambitions:
Understanding and managing our new and future relation with the Earth requires research and knowledge spanning diverse fields. Earth's Future will explore and foster interactions among the Earth and environmental sciences, ecology, economics, the health and social sciences, and more. Its mission is to focus on the Earth as an interactive, evolving system to help researchers, policy makers, and the public navigate the science.
Earlier this month I was browsing the Earth's Future website when I noticed a recently accepted paper with the arresting title "Decadal reduction of Chinese agriculture after a regional nuclear war."
For decades, scientists have worried that the blasts from nuclear weapons could start fires that would produce soot, which would be carried high into the troposphere. Rain would flush out some of the soot, but much of it, warmed by the Sun, would be lofted into the rainless stratosphere. There, it could circulate for years and intercept so much sunlight that surface temperatures would plummet.
Part of Operation Plumbbob, the Fizeau test took place at the Nevada Test Site on 14 September 1957. In altitude and terrain, the site resembles parts of the Indian state of Rajasthan and parts of the Pakistani state of Balochistan. CREDIT: Alex Wellerstein
The original authors of that nuclear winter scenario had in mind an intercontinental war between the US and the USSR. But a regional war between India and Pakistan that used much less than 1% of the world’s nuclear arsenal could still inject about 5 teragrams of soot into the upper troposphere. Now Lili Xia of Rutgers University and her collaborators have estimated the agricultural impact of such a war on the world’s largest producer of grain, China.
The researchers used the results of three different models to track the Chinese climate for 10 years after an initial injection of 5 Tg of soot. All three models yielded more or less the same result: The soot significantly reduced temperature, rainfall, and sunlight throughout China for the entire decade.
Xia and her collaborators then fed those parameters into a crop model. One year after the war, annual production of maize, rice, and wheat fell by an average of 35%. Even with increased use of irrigation and fertilizer, grain production four years later was still 25% lower than it had been before the hypothetical war. Given that the impact on US and European agriculture would likely be as severe, the war could put a billion people at risk of famine.
Brasseur and Van der Pluijm did not explicitly mention war in their introductory editorial, but they did highlight the need for international, interdisciplinary approaches to mitigating the environmental and socioeconomic effects of "hazards such as earthquakes and extreme weather, air and water quality, sea-level rise, reduction in biodiversity, and so on."
"And so on" surely includes a nuclear war, even a limited one.
