The carbon crunch

The world must cut agricultural emissions by an estimated two-thirds by 2050 to help fight climate change while simultaneously producing 50 percent more food, said an American researcher.

Serious efforts must be made to put “real money into what I call collaborative projects … where farmers, scientists, the private sector are working together to explore how to do things,” said Tim Searchinger, senior research scholar at the Centre for Policy Research on Energy and the Environment at Princeton University.

He spoke at a recent online seminar on sustainable intensification in agriculture hosted by the Canadian Agri-Food Policy Institute.

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Searchinger was the lead author of a report in 2019 for the World Bank, the United Nations and the World Resources Institute that addressed “the question of how we feed the world in 2050 while reducing greenhouse gas emissions — basically without destroying the world.”

He said global agriculture emits about 12 billion tonnes of carbon dioxide equivalent (CO2e) per year, which is a measure used for greenhouse gases.

It amounts to nearly 25 percent of the world’s total annual emissions of about 50 billion tonnes.

The maximum from all human sources needs to be cut by 2050 to a maximum of “21 billion tonnes, probably more like 20 or even 17,” he said. “For agriculture to do its fair share, total agricultural emissions should be about four.”

However, not only is the total global population expected to rise to about 10 billion by 2050, “more of these people are going to have decent incomes, so they can eat better,” he said.

Much of the developing world currently suffers from poor diets, said Searchinger, who is also a senior fellow at the World Resources Institute and technical director of its food program.

“And what that means is we have to produce about 50 percent more food with one-third of the emissions … and that means converting no more agricultural land. No more land; you have to produce all that additional food on the same land.”

A large source of emissions involves things such as drained peatland, with agriculture already occupying about half the world’s vegetated land, he said.

“Now a critical concept is the importance of valuing the land properly…. We cannot solve climate change if we convert more forests to agricultural land.”

Meanwhile, proposals to convert cropland into grazing land as part of regenerative agriculture “will absorb carbon, but produce so much less food that it can’t be a part of the solution.”

It is also extraordinarily inefficient to grow crops for biofuel, he said. Corn land only converts about 0.15 percent of the energy in the sun into usable energy compared to about 20 percent for photovoltaic cells, he said.

Searchinger said solving the dilemma of drastically cutting emissions while substantially boosting yields requires a multi-part strategy that he broadly referred to as produce, protect, reduce and restore.

“Produce more food on the same land; use that to protect forests and other habitat from being converted, which has to be done explicitly; reduce demand for land and reduce production emissions; and then selectively restore areas where we can.”

About a third of the world’s grazing land was converted from forests, he said, explaining that in the U.S. about “half of the emissions, half of the land use — and the greenhouse gas emissions from land use are more important — they all come from beef, even though it supplies only three percent of our calories.”

Along with crop breeding, boosting the efficiency of raising livestock through feed and genetics is a critical component of efforts to increase yields while cutting emissions, he said.

“If you’re in the beef production business, we need you to continue to produce beef efficiently. It’s not like beef consumption isn’t going to continue to rise. But we need to hold down that amount.”

World consumption of animal products is expected to soar about 70 percent from 2010 to 2050.

“Now as a result of that, even if agriculture continues to make the same kind of productivity gains as it’s done since 1960 at the same rate, greenhouse gas emissions from agriculture will go up to about 15 billion tonnes.”

Due to the fact Canada has an advanced agriculture sector, its emissions per unit of food are relatively low compared to the rest of the world as a whole, “and that means Canadian agriculture is very valuable,” said Searchinger.

“But even so, we can’t solve the problem unless we make a lot of improvements, and the idea is to formulate different teams and put real money into it, and solve each one of these different types of problems.”

Many of the easier things farmers have relied on to increase yields have largely already been implemented in much of the world, he said, pointing to irrigation and chemical fertilizers. Producers “basically (now) have to do everything smart.”

However, he said the current research system isn’t responding fast enough.

“Right now, what we do is we get a research project, it gets written up, somebody thinks about it a year later, somebody decides whether to fund another research project who follows up on that.

“That is not the pace at which we need to go to solve these challenges.”

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