Global environmental footprint of food

DAILY SCIENCE

A novel look at the global footprint of food uncovers some eye-opening insights

For example, almost half of all environmental pressures from food production come from just five countries.
November 11, 2022

Almost half the cumulative environmental impact of our food systems derives from just five countries. This, plus a host of other revelations about food impacts, have been shared in a new study, which its authors say could help tailor efforts to make global production more sustainable.

Usually, we tally food impacts by, for instance, looking at the greenhouse gas (GHG) emissions linked to a liter of milk. But this single-impact focus, usually applied to distinct food groups, fails to capture the full catalog of pressures—like habitat destruction and water use—that foods place on the environment. It also overlooks the fact that the impacts of food production aren’t felt uniformly across the planet, but will vary geographically, especially when factoring in GHG emissions and other transboundary impacts. 

The researchers on the new Nature Sustainability study hoped to counter these shortcomings with a different way of estimating the pressures that food systems place on our planet. Their study pooled global production data from 2017, covering 99% of global food products, and originating from 172 nations. They looked at four environmental impacts associated with the production of each food in each country: greenhouse gas emissions, nutrient pollution from fertilizer run-off, freshwater use, and habitat disturbance. 

Crucially, they then combined these four pressures to create one geographically-explicit estimate of cumulative food production impacts in each case.

In the first instance, this approach revealed that responsibility for global food impacts is heavily skewed to specific parts of the planet. In fact, just five nations—India, China, the United States, Brazil, and Pakistan—account for 43.8% of the global cumulative impact of producing food, the study shows.

Of this, terrestrial food production contributes a larger cumulative pressure than do aquatic sources of food. And yet, despite providing just 1.1% of global nourishment, food from the ocean causes a surprisingly large 10% of cumulative environmental pressure, due to the effects of habitat disturbance, the researchers found. 

 

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Individual foods can have wildly different footprints, depending on how they're produced

 

Meanwhile, nearly all this environmental pressure—about 92%—plays out on just 10% of Earth’s surface, mainly in India, China, the United States, Brazil and Indonesia, the analysis showed.

Measuring the fuller cumulative pressures of different food types also revealed some surprising new high-impact candidates. Beef production is widely accepted as being the worst for the planet because of the associated emissions—but when factoring in water use and pollution, pig farming actually has the larger cumulative environmental footprint. Similarly, some types of fish pose bigger environmental pressures than chicken does. 

When impacts were interrogated at national scales, the results morphed again, revealing that for most nations (with the exception of countries like Brazil) the largest cumulative environmental pressures come from crops such as rice and wheat, which need large amounts of water and cause lots of nutrient pollution.

Drilling further into national differences in food production impacts, the researchers also discovered how variable production methods around the world can dramatically alter the environmental footprints of similar foods. Across nations, the environmental pressures posed by the same food types varied up to tenfold, depending on where those foods were produced. 

Take soybeans, which are 2.4 times more efficient—and therefore less impactful—when farmed in America than in India, because US farmers have access to technologies that have helped them increase yields and lower GHG emissions. 

The researchers explain how this comprehensive assessment of food production pressures, distinguished by geography, creates new vantage points on the problem—and with it, new opportunities to tackle it.

For instance, identifying the major ‘culprit’ nations behind the majority of global food impacts helps illuminate where interventions might have the biggest global effect. Finding where food systems impose their biggest planetary impacts could guide mitigation and remediation efforts in those regions. And at more localized scales, comparing the footprints of similar foods across nations could reveal where farming methods in some countries could be improved to bring impacts down, the researchers say

“We need this comprehensive information to make more accurate decisions about what we eat.”

Halpern et. al. “The environmental footprint of global food production.” Nature Sustainability. 2022.

Image: ©Anthropocene Magazine

 

 

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