RACHEL MARTIN, HOST:
If the world doesn't address climate change, there could be a global food crisis. That is the warning in a new U.N. report examining food production and global warming. The window to address the problem is closing. Dan Charles from NPR's Science Desk joins us now to talk about this. Hi, Dan.
DAN CHARLES, BYLINE: Hi, Rachel.
MARTIN: So the U.N. report says we're on our way to a global food crisis. How?
CHARLES: Well, the first point to make is that climate change itself can make it harder to grow a lot of food across much of the world. You have shifting rainfall. You have increasing heat, which itself stresses crops. You have shifting production from one place to another - could be a lot of dislocation. In some areas, there will be more food production, in far northern latitudes. But on balance, in much of the world - in most of the world, the projections are that increasing heat will make it harder to grow enough food.
MARTIN: And we should say the way most food is grown right now can itself mean higher emissions, right?
CHARLES: Well, that is the other really big part of this report. I mean, I should also say, the report assumes that there will be more people with higher incomes wanting more food.
CHARLES: So actually, food production has to expand. And the way the - you know, we've expanded food production historically in the world is we've claimed more land. We've cut down forests. We've plowed up grasslands, like the entire Great Plains of the U.S.
MARTIN: Right. You need land for cattle. You need land for farms, industrial farms.
CHARLES: And that releases huge amounts of carbon dioxide. It's like mining the soil the same way you would, like, mine coal and burn it. And there are other sources as well. The - sort of the production of nitrogen fertilizer is incredibly intensive releaser of greenhouse gases. And methane from cattle as they - you know, sort of they convert grass into meat, they release methane. That's also a source of greenhouse gases. So on balance, all of those things - mining the soil, cattle, fertilizer - it's estimated that food production by itself accounts for close to a quarter of all greenhouse emissions in the world.
MARTIN: Are any of those things biofuels? Because the report specifically calls out biofuels.
CHARLES: Biofuels is an interesting question. Biofuels have been presented as a solution to climate change because you're getting fuel basically from the sun and from the Earth instead of burning coal or natural gas. The thing about biofuels is you need land. And remember, land is scarce, especially if you're trying to increase food production. And so that increases the demand for agricultural land. And it - if you do it on a large scale, it means cutting down more forests, you know, plowing up more grasslands. Maybe the land would be better just as it is growing grass and putting carbon back in the soil.
MARTIN: So these are all the problems, which are big and dire and overwhelming, to be frank. What about solutions? I mean, if the U.N. report is issuing yet another warning linking climate change and our inability to address it with a global food crisis, what do scientists right now say needs to be done?
CHARLES: So there are actually solutions. This doesn't have to be, you know, all gloom and doom and dire. OK, so let's start with stopping the cutting-down of more forests. That's, like, point one. And so you continue to grow more food on the same amount of land, ideally less land.
MARTIN: How do you do that, though? (Laughter).
CHARLES: Well, productivity has been increasing. And there is plenty of technological scope for increasing production more. Another side of this is shifting diets. We have a vast amount of land that is devoted, for instance, to feeding animals for meat. Shifts in diet away from meat could also free up more land, either for growing trees, putting carbon back in the soil, or for growing more fruits and vegetables to feed more people.
MARTIN: All right. NPR's Dan Charles, helping us understand this new warning being issued by the U.N. We appreciate it, Dan. Thank you.
CHARLES: Glad to be here. Transcript provided by NPR, Copyright NPR.