DAVID GREENE, HOST:
When it comes to the U.N.'s assessment of climate change, the conclusion has not changed but the language has. The evidence is now, quote, "unequivocal" that the planet has warmed significantly over the past century and human activity is mostly the cause. Yesterday, in Copenhagen, scientists released the latest report from the Intergovernmental Panel on Climate Change. And NPR science correspondent Christopher Joyce is in the studio with me to talk about it. Chris, good morning.
CHRISTOPHER JOYCE, BYLINE: Glad to be here.
GREENE: So Chris, we've heard reports like this before - it sounds like the language is different. Does that mean that the assessment is different in some large way compared to reports in the past?
JOYCE: It does. It shows that the scientists are more confident in the conclusions that the climate is warning and they're more urgent of their predictions of what can happen if that warming continues unabated. In a word - it's grimmer. This is the fifth IPCC assessment that's come out since 1990. They used to use words like probable and very likely about warming. Now they're using words like unequivocal. They're saying it's now, quote, unquote "extremely likely" that humans are causing this. It's basically the reflection of evidence that they've been collecting over the years - sea level rise that hasn't been seen in 2000 years, flooding that's caused because of that, heat waves that are off the charts. We're seeing insects and wildlife and marine animals that are moving away from warmer waters. It's a whole litany of things that they've observed that were predicted.
GREENE: Things happening now. I mean, not things that they're warning about in the future.
GREENE: Actual changes that they're seeing now.
GREENE: What about the emissions - the greenhouse gases - that cause warming? I mean, are they still going up, which would make things, you know, even more worrisome?
JOYCE: Yes, that's the grim part. The greenhouse gas emissions right now are higher than any time in history. One thing that this assessment did that hasn't been done in the past, they put a number on the amount of CO2 and carbon in the atmosphere that's going to push us above a certain threshold - 3.5-3.6 degrees Fahrenheit. That number is a trillion tons of carbon. Right now, we're halfway there and they predict that in 30 years or so we could reach the trillion-mark and at which point we exceed 3.5 and things get really, seriously bad - melting ice sheets, severe droughts, agricultural losses.
GREENE: Chris, help us sort this out. I mean, I've read that the Kyoto treaty, this big international agreement about climate change, has actually helped lower emissions in Europe. And also here in the United States, emissions have gone down - that all sounds like good news. Why is that not translating into, you know, a less grim report?
JOYCE: There is some good news in the present. I mean, emissions have come down. In the United States, have come down 10 percent in the past seven years - Europe, they've come down. But the problem is that the developing world is using coal and oil. They want to consume like we consume and their emissions are going up, and that's where the big emissions are going to come from in the future. Now, the IPCC said yes, there are technologies that are available. But to give you a number on that, I mean, right now, zero-carbon energy for electricity, for example - nuclear, wind, solar, that sort of thing - it amounts to 30 percent of the electricity that the world gets. That has to go up to 80 percent in the next 30 years, according to the IPCC, and that is a tall order.
GREENE: Is there some sort of pressure now - political pressure - that will build for a new treaty or new sort of agreement to bring both developing countries and developed countries together to do something? I mean, now that we're seeing a report this ominous.
JOYCE: Yes, I mean, this report provides a scientific foundation for the ongoing negotiations. The Kyoto treaty that was in existence, expired in 2012. They've failed - they meaning governments around the world - since then to come up with a new one. They're meeting next year. There's a big push to say look this is the time to act and this scientific study is probably the biggest impetus they've got so far to sort of get up and go.
GREENE: All right. NPR's Christopher Joyce talking to us about a new climate change report that suggests the climate is changing faster than we previously thought. Chris, thanks a lot.
JOYCE: Glad to be here.
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