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How to Grow More Food While Slowing Climate Change

Avoiding bare fields can increase soil carbon storage. (Whatlep / Wikimedia Commons)

Two new studies have confirmed that farmers can win both ways, achieving a boost in harvests and helping to slow climate change.

One says that they can successfully farm with techniques that can help slow global warming and add to the store of carbon sequestered in the soils around the globe.

And a second study confirms that a range of tested and sustainable practices is already stepping up yields in small farms worldwide, while dramatically reducing greenhouse gas emissions, soil erosion and pesticide use.

Both studies address a planetary dilemma. Global agriculture is at serious risk from global warming and climate change driven by profligate fossil fuel combustion. But global agriculture – powered by greenhouse gas-emitting fossil fuels, ploughing, pesticides and herbicides – is also helping to drive global warming and climate change.

Massive changes needed

And while researchers have persistently argued that it should be possible both to feed the 9bn people expected by 2050, and to contain global warming to no more than 2°C by 2100, such advances can be achieved only by massive changes in diet and expectations. But both new studies focus on what is both practicable and possible right now.

US researchers report in the journal Science Advances that they have identified a range of well-established farming practices that – if adopted by everybody – could capture enough carbon from the atmosphere and store it in the world’s soils at a rate that could make a significant difference.

They suggest that simple approaches – cover crops, more thoughtful use of grazing animals, the planting of legumes on rangelands and so on – could, if coupled with dramatic reductions in carbon dioxide emissions, notionally add as much as 1.78 billion tonnes of carbon from the atmosphere to soils, lowering temperatures by 0.26°C. Since 1880, global average temperatures have already risen by about 1°C.

More tentatively, they suggest that if farmers added biochar – the residue of crops burned to make charcoal – to their soils, this could reduce global warming by as much as 0.46°C.

“I’m impressed by how far farmers across the world and especially in less developed countries have come in moving our food-production systems in a healthy direction.

Massive shifts to renewable energy worldwide would also be necessary: ever more carbon dioxide in the atmosphere would make changes in farming practices proportionately ever less effective. The bonus is that more carbon drawn down from the atmosphere and stored in the soil would pay off with healthier soils and better crop conditions.

“These are very commonly used approaches, though people don’t use them to sequester carbon – they are doing it for other reasons”, said Whendee Silver, an ecosystem ecologist at the University of California at Berkeley, and one of the authors.

“Any time you increase the organic content of soils, you are generally increasing the fertility, water-holding capacity, sustainability, decreasing erosion and increasing general resilience to climate change. Sequestering carbon is a side benefit.”

Costs lowered

In the same week, scientists from five nations reported in the journal Nature Sustainability that they could show that farming practices that show consideration for the global environment can and do deliver more food at lower costs.

Enthusiasts and environmentalists have been promoting “organic” or sustainable farming for decades. What the scientists call “sustainable intensification” is already employed in around a tenth of the world’s farmlands.

They looked at data and reports from 400 sustainable intensification initiatives – agroforestry is one example – used on either more than 10,000 farms or over 10,000 hectares of farmland. Altogether, their survey covered an estimated 163 million farms.

And their study showed that productivity went up, biodiversity and ecosystem services were conserved, yet costs were down.

Food for all

In West Africa, farmers were growing more cassava and maize. In Cuba, 100,000 farmers had stepped up yields by 150% while reducing pesticide use by 85%.

“Although we have a long way to go, I’m impressed by how far farmers across the world and especially in less developed countries have come in moving our food-production systems in a healthy direction,” said John Reganold, a soil scientist at Washington State University in the US, and one of the authors.

“Stronger government policies across the globe are now needed to support the greater adoption of sustainable intensification farming systems so that the United Nations Sustainable Development Goals endorsed by all members of the UN are met by 2030.

“This will help provide sufficient and nutritious food for all, while minimising environmental impact and enabling producers to earn a decent living.”

Tim Radford / Climate News Network

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