Humans must drastically alter food production to prevent the most catastrophic effects of global warming, according to a new report from the United Nations panel on climate change.
The panel of scientists looked at the climate change effects of agriculture, deforestation and other land use, such as harvesting peat and managing grasslands and wetlands. Together, those activities generate about a third of human greenhouse gas emissions, including more than 40% of methane.
That's important because methane is particularly good at trapping heat in the atmosphere. And the problem is getting more severe.
"Emissions from agricultural production are projected to increase," the authors warn. "Delaying action" on reducing greenhouse gas emissions, they continue, "could result in some irreversible impacts on some ecosystems."
This is the latest in a series of reports from the U.N.'s Intergovernmental Panel on Climate Change. The new report adds weight and detail to a warning put out by the same panel of scientists last fall, in which they sounded the alarm about the inadequacy of the pledges countries have made so far to reduce greenhouse gas emissions.
At that time, the panel broadly suggested that farmland would need to shrink and forests would need to grow to keep Earth from getting more than 1.5 degrees Celsius hotter than it was in the preindustrial era. Global temperatures have already risen about 1 degree Celsius in the past 150 years.
To meet that temperature target, global greenhouse gas emissions will need to fall by 40% to 50% in the next decade. Scientists say the only way to achieve that reduction is to significantly increase the amount of land that's covered in trees and other vegetation and significantly reduce the amount of methane and other greenhouse gases that come from raising livestock such as cows, sheep and goats.
The new report offers some broad suggestions for how countries might achieve that. For example, for countries that have lost tree cover in the past century, reforestation can help suck greenhouse gases out of the air, while also preventing soil from drying up. Reducing food waste can also help: The report estimates food waste accounts for as much as 10 percent of human-induced greenhouse gas emissions. (Check out these tips on reducing food waste in your own home.)
Controlling emissions from agriculture is also a food-security issue. Greenhouse gases from food production create a vicious cycle: As Earth gets hotter, farming gets more difficult in many places, which forces farmers to clear more land to grow food.
"Climate change, including increases in frequency and intensity of extremes, has adversely impacted food security and terrestrial ecosystems, as well as contributed to desertification and land degradation in many regions," the report's authors write.
If greenhouse gas emissions continue to increase, as they are doing today, it will exacerbate those challenges and eventually make it all but impossible to control global warming without creating serious food shortages.
The U.N. panel is the latest group of experts to grapple with a global conundrum: how to reduce greenhouse gas emissions from agriculture, deforestation and other land use without creating food shortages or displacing people whose livelihoods rely on practices that are unsustainable globally.
Scientists and economists have been studying the effects of our diets on the environment for years. There's a growing consensus that a transition to a more plant-centered diet would help.
Currently, about 50% of the globe's vegetated land is dedicated to agriculture — and about 30% of cropland is used to grow grain for animal feed. Given how much land it takes to grow food to feed livestock, meat production is a leading cause of deforestation.
A report released last month by the World Resources Institute finds that if current dietary patterns continue, an additional 593 million hectares — which is almost twice the size of India — would be needed to feed the projected 9.8 billion people (the anticipated population) by 2050.
Right now, agriculture generates an estimated 25% of annual greenhouse gas emissions, according to the WRI; that's when you combine food production and the land-use changes associated with farming, such as clearing vegetation and plowing.
If current trends continue, but agricultural productivity does not increase beyond 2010 levels, the WRI report concludes that most of the globe's remaining forests would need to be cleared to feed the world. And the globe would exceed the greenhouse gas emission targets set by the Paris climate agreement.
As we've reported:
"The WRI estimates that if people in the U.S. and other heavy meat-eating countries reduced their consumption of beef (and other meat from ruminants) to about 1.5 burgers per person, per week, it would 'nearly eliminate the need for additional agricultural expansion (and associated deforestation), even in a world with 10 billion people.' "
AUDIE CORNISH, HOST:
NPR's Allison Aubrey joins us now to talk about how our own eating habits can play into climate change.
Allison, welcome to the studio.
ALLISON AUBREY, BYLINE: Hi there.
CORNISH: So we've just heard from Dan Charles that there's this need to grow more food from less land. How would shifting our own diets personally help make that happen?
AUBREY: The big picture here is that if people in countries that consume a lot of meat - and that is definitely us here in the U.S. - cut way back, it could lead to a significant reduction in greenhouse gas emissions. And one goal that experts have come up with is to eat no more than one hamburger worth of red meat per week. We'll come back to that in a minute, but let me explain why.
It takes a whole lot of land to produce meat. If you think about it this way, imagine around the globe all of the crop land out there - one-third of it is used to grow food not for people but for animals. It's animal feed. And when you combine the land needed to graze animals and feed them, this is just a whole lot. The World Resources Institute has estimated that for every gram of protein, producing beef can require 20 times the land and emit 20 times the emissions compared to what it takes to produce beans.
CORNISH: So are there certain types of meat that are better in terms of environmental footprint? Or basically is the suggestion that we should not be eating meat?
AUBREY: There are definitely better choices, and it does not have to be all or nothing. I just mentioned cows and other ruminants. They require a lot of land and feed. But they also release a lot of methane into the atmosphere. Every time these animals belch, a bit of methane goes up into the atmosphere. Methane is a very potent greenhouse gas.
So from an environmental perspective, options such as chicken and turkey can be better. It takes less animal feed to produce meat from these animals. They grow faster. They require less land. So when it comes to reducing the environmental footprint of your diet, you don't have to completely give up meat.
CORNISH: So what is the environmentally sound supplement - right - to that meat eating that we won't be doing?
AUBREY: Sure. Well, I'd say that there is a consensus that has emerged, and that is that a plant-based diet can be better for both the planet and for our health. There was this big report that came out earlier this year, the EAT-Lancet Commission report. It found that if you limit red meat to about 3.5 ounces a week - that's the one hamburger I mentioned - and instead you eat more fruits, vegetables, whole grains, that this can lower the risk of cardiovascular disease.
And when it comes to getting enough protein, you'll hear people say, oh, I need protein. I need meat. The research shows that if you eat plant-based proteins such as nuts and beans in lieu of the animal protein, there is a lower risk of death from heart disease.
So just to help connect the dots back to the sustainability issue - by one estimate, if people in the U.S. switched from beef to beans, this switch alone could get us more than half way to the greenhouse gas reduction targets set during the Obama administration, which is kind of crazy to think about.
CORNISH: Yeah. My mind is wrapping around that as you're saying it. I want to talk about another angle of this food waste because we hear that about 30% of food produced is actually wasted. Can reducing food waste affect this at all?
AUBREY: Absolutely. I mean, people should waste less of what they buy. I mean, it's estimated that the typical family in the U.S. tosses out about $1,600 of groceries a year. And the report out today from the U.N. finds that food waste may contribute up to 10% of the human-made greenhouse gas emissions. So we have a whole bunch of tips on our website to help you shop smarter and waste less in your own homes.
CORNISH: That's NPR's Allison Aubrey.
Allison, thanks for sharing this with us.
AUBREY: Thanks so much. Transcript provided by NPR, Copyright NPR.