RACHEL MARTIN, HOST:
Author David Wallace-Wells opens his new book, "The Uninhabitable Earth," outlining three misunderstandings about climate change - first its speed...
DAVID WALLACE-WELLS: More than half of all of the fossil fuel emissions that we've ever put into the atmosphere have come in the last 25 years, which means that we've now done more damage to the climate than in all of the millennia before and all of the centuries before.
MARTIN: ...Then its scope...
WALLACE-WELLS: We were sort of taught the problem was really about sea level and coastlines. We're starting to see that climate change is really an all-enveloping threat, which promises to transform, probably deform every life lived on the planet in some way.
MARTIN: ...And finally, its severity.
WALLACE-WELLS: It was basically considered irresponsible to consider scenarios north of about 2 degrees of warming. It was called the threshold of catastrophe, and nobody really wanted to think about it. It turns out that 2 degrees looks basically like our floor for warming rather than our ceiling. And so we really need to start thinking about what the impacts will be at 2 1/2, 3 and even 4 degrees of warming.
MARTIN: I asked him to explain what that kind of warming would look like.
WALLACE-WELLS: The absolute worst-case scenario is that the planet becomes uninhabitable. I think that that is vanishingly unlikely on any timescale that it makes sense for us to think about. But the crazy thing is I don't think you need to look at worst-case scenarios.
WALLACE-WELLS: So end of the century, the U.N. says we're going to be at about 4.3 degrees of warming if we don't change course. 4.3 degrees of warming would mean $600 trillion in damages from climate impacts. Six hundred trillion dollars is double all of the wealth that exists in the world today. Our agriculture would probably be about half as bountiful, so the same plot of land would be producing about half as much yield in a world that we would have at least 50 percent more people to feed.
We would have places in the world that could be dealing with six climate natural disasters simultaneously. And as soon as 2050, it's likely that many of the biggest cities in the Middle East and India will be unlivably (ph) hot in the summer. So it will be a lethal risk to set foot outside in the summer in places like Kolkata and Delhi. And U.N. estimates for the number of climate refugees that could be produced just by 2050 - on the conservative end of their estimates, we're dealing with 100 million climate refugees by 2050.
MARTIN: So there's a lot in there. Let's try to unpack some of what you just laid out - in particular, 100 million migrants as a result of climate change. How do you deal with that? Because that is, in part, where we have seen anti-immigrant populist movements explode - across Europe, in the United States. When climate is driving so many people to look for sanctuary in other resource-rich countries, the natural tendency is to say, yeah, maybe we need to figure out ways to keep them out or to at least save our own.
WALLACE-WELLS: Yeah. I mean, if you had to imagine a threat large enough to really call into being a true network of global cooperation, climate change would be it. Its all-encompassing. It challenges the lives of everybody everywhere on the planet. And yet, it's really reaching a crisis point as we're all retreating from our international agreements and commitments. How do these climate impacts transform the relationship between nations and the responsibilities that we feel towards one another?
One quite alarming possibility is the one that we're seeing today, which is that nations recoil. Another possibility is that we will be kind of called into a kind of brotherhood, sisterhood where we realize that we're all dealing with this threat together, we all bear some responsibility for it and we should do everything we can collectively to deal with it. But I don't think that's - you know, I don't think it's a safe bet that we'll end up in that happy place.
MARTIN: You have laid out what you describe as really apocalyptic consequences. How do you deal with the human tendency to curl up in a ball and walk away from the problem? Regular people, when they hear this, they will think - how can I possibly make a difference in this? I am not a politician. I'm not a lawmaker. I'm not a scientist. And it is depressing to live in this headspace.
WALLACE-WELLS: Yeah. No, it's bleak. But I have to say that optimism is really always a matter of perspective. I think many of us have been taught to think about the range of possible outcomes for climate change as between where we are now or even zero degrees of warming and 2 degrees of warming. And I know that the range of possible outcomes this century is between 2 degrees and 4 degrees of warming.
So how optimistic I am is based as much around 4 degrees of warming as it is around 2. Now, 2 degrees is hellish enough. I think it's about our best-case scenario, and it is truly alarming. If we get to 2 degrees, one really remarkable paper demonstrated last year, the air pollution effects alone would kill an additional 150 million people beyond what the air pollution at 1.5 degrees would would cost. That is our best-case scenario. So when I talk about being optimistic, I'm talking about a range that starts at a death toll of 150 million people and extends to a world 4 degrees warmer where we would have, eventually, hundreds of feet of sea level rise, horrible impacts on agriculture and public health beyond our comprehension.
Now, a lot of people would want to just sort of recoil from even that best-case scenario.
WALLACE-WELLS: And I think that is a human impulse. But my own instinct is to say every inch of warming makes a difference - every inch of warming means averting some suffering or causing more suffering - and that at no point should we give up because while, on the one hand, it's already too late to avert anything south of 2 degrees of warming, it's also never too late to change the course of our warming and make lives more prosperous and healthier and safer and more abundant and happier going forward.
And so we should never, ever stop caring, never give up because it is always possible to make a difference, and I think that we will. I do not think that we'll end up at 4 degrees. I think it's likely we end up at about 2 1/2 or 3 degrees by the end of this century. That, again, will be, to any perspective that we know today, hellish. But if you know what's possible at 4 degrees or north of 4 degrees, it counts as an optimistic outcome. And that's where I am.
MARTIN: "The Uninhabitable Earth: Life After Warming," written by David Wallace-Wells - thanks so much for talking with us.
WALLACE-WELLS: Great to be here. Thank you.
(SOUNDBITE OF PIANO NOVEL'S "YAMABIKO")
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