Human activities are currently estimated to produce around 40 billion tonnes of carbon-dioxide equivalent every year. Model results indicate that agricultural adaptation measures would prevent around 350 million tonnes of carbon-dioxide emissions annually – equivalent to around 1% of total global emissions.

Adapting to climate change or mitigating climate change – which would you choose to invest your cash in? Mitigation and adaptation are often viewed as separate activities, with the former aiming to reduce greenhouse-gas emissions and the latter helping adjust to expected increases in greenhouse gases. A new study shows that when it comes to agriculture, adaptation measures can also generate significant mitigation effects, making them a highly worthwhile investment.

Food production is big. If farmers fail to adapt to climate change we can expect to see more land being turned over to agriculture, in order to keep up with food demand. With this in mind, David Lobell, from Stanford University, US, and colleagues used a model of global agricultural trade to investigate the co-benefits of helping farmers adapt to climate change, thereby avoiding some of the emissions associated with land-use change.

Running their model to 2050, they show that an investment of $225 bn in agricultural adaptation measures can be expected to offset the negative yield impacts associated with predicted temperature and rainfall changes. But that’s not all – the model revealed that this investment would also save 61 million hectares from conversion to cropland, resulting in 15 Gtonnes carbon-dioxide equivalent fewer emissions by 2050.

"I don't think any of us expected the mitigation benefits to be as big as they were," said Lobell, whose findings are published in Environmental Research Letters (ERL). "We had a hunch that they would be big enough to be an important co-benefit, but the fact they were often big enough to rival other mitigation activities was surprising."

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It’s no secret that China is faced with some of the world’s worst pollution. Until now, however, information on the magnitude, scope and impacts of a major contributor to that pollution – human-caused nitrogen emissions – was lacking.

A new study co-authored by Stanford Woods Institute Senior Fellow Peter Vitousek (Biology) reveals, among other findings, that amounts of nitrogen deposited on land and water in China by way of rain, dust and other carriers increased by 60 percent annually from the 1980s to the 2000s, with profound consequences for the country’s people and ecosystems. Xuejun Liu and Fusuo Zhang at China Agricultural University in Beijing led the study, which is part of an ongoing collaboration with Stanford aimed at reducing agricultural nutrient pollution while increasing food production in China – a collaboration that includes Vitousek and Pamela Matson, a Stanford Woods Institute senior fellow and dean of the School of Earth Sciences. The researchers analyzed all available data on bulk nitrogen deposition results from monitoring sites throughout China from 1980 to 2010.

During the past 30 years, China has become by far the largest creator and emitter of nitrogen globally. The country’s use of nitrogen as a fertilizer increased about threefold from the 1980s to 2000s, while livestock numbers and coal combustion increased about fourfold, and the number of automobiles about 20-fold. All of these activities release reactive nitrogen into the environment. Increased levels of nitrogen have led to a range of deleterious impacts, including decreased air quality, acidification of soil and water, increased greenhouse gas concentrations and reduced biological diversity.

“All these changes can be linked to a common driving factor: strong economic growth, which has led to continuous increases in agricultural and nonagricultural reactive nitrogen emissions and consequently increased nitrogen deposition,” the study’s authors write.

Researchers found highly significant increases in bulk nitrogen deposition since the 1980s in China’s industrialized north, southeast and southwest regions. Nitrogen levels on the North China Plain are much higher than those observed in any region in the U.S., and are comparable to the maximum values observed in the U.K. and the Netherlands when nitrogen deposition was at its peak in the 1980s.

China’s rapid industrialization and agricultural expansion have led to continuous increases in nitrogen emissions and nitrogen deposition. China’s production and use of nitrogen-based fertilizers is greater than that of the U.S. and the E.U. combined. Because of inefficiencies, more than half of that fertilizer is lost to the environment in gaseous or dissolved forms.

China’s nitrogen deposition problem could be brought under control, the study’s authors state, if the country’s environmental policy focused on improving nitrogen agricultural use efficiency and reducing nitrogen emissions from all sources, including industry and transit.