美国国家公共电台 NPR James Hansen: What Makes A Scientist Take A Stand?（在线收听）

GUY RAZ, HOST:

It's the TED Radio Hour from NPR. I'm Guy Raz. And on the show today, Speaking Up, ideas about what it takes and when you know it's time to say something.

JAMES HANSEN: As the ocean gets warmer that melts the ice shelves that come out from Antarctica and Greenland into the ocean.

RAZ: This is climate scientist James Hansen.

HANSEN: So if you once get the ocean to warm, there's practically no way to stop it.

RAZ: And the impact of climate change on the planet was why he testified in front of Congress back in 2014.

(SOUNDBITE OF ARCHIVED RECORDING)

HANSEN: The statement that you just made is blatantly false. We do know...

UNIDENTIFIED MAN: How do you explain climate change has occurred 10,000 years ago before man had a carbon print? All those...

HANSEN: No one said it is all manmade. There are natural...

UNIDENTIFIED MAN: Well, that's the - kind of the attack that environmentalists take.

HANSEN: However, the manmade effect is now dominant. This decade is going to be warmer than the last one, and the following one will be still warmer.

RAZ: But here's the thing. This wasn't the first time James was speaking up on Capitol Hill because back in the 1980s, he was one of the first scientists to warn Congress and the world, really, about climate change.

HANSEN: Actually, my first testimony was after my first major paper on climate which was published in Science in 1981.

RAZ: And at the time, James was a leading scientist at NASA. And his article in Science magazine was kind of a big deal.

HANSEN: This paper pretty much told the story that you can't burn all the fossil fuels and still keep a planet that looks like the one that civilization developed on.

RAZ: James Hansen picks up the story from the TED stage.

HANSEN: In 1981, we published an article in Science magazine concluding that Earth would likely warm in the 1980s, and warming would exceed the noise level of random weather by the end of the century. We also said that the 21st century would see shifting climate zones, creation of drought-prone regions in North America and Asia, erosion of ice sheets, rising sea levels and opening of the fabled Northwest Passage.

That paper led to me testifying to Congress in the 1980s testimony in which I emphasized that global warming increases both extremes of the Earth's water cycle - heatwaves and droughts on one hand directly from the warming, but also because a warmer atmosphere holds more water vapor with its latent energy, rainfall will become more extreme events. There will be stronger storms and greater flooding. All of these impacts have since either happened or are now well underway.

RAZ: OK. So this might all sound normal now, but that testimony which was in 1988 was really important because James and a few other scientists did something that was kind of frowned upon in the scientific community. In Congress, they spoke up, and they said climate change is real.

(SOUNDBITE OF ARCHIVED RECORDING)

HANSEN: Altogether, this evidence represents a very strong case in my opinion that the greenhouse effect has been detected, and it is changing our climate now.

Yeah. Yeah that's what we said, but it's - things haven't changed.

RAZ: But when you made that testimony, was it risky for you? Were there people who said, you know, like what are you doing?

HANSEN: The 1988 testimony was risky in the sense of the scientific community was likely to have some backlash about that because the scientific community is reticent to speak out until things are so certain that there's no possibility of having something wrong.

RAZ: And there was backlash. Some people said James Hansen was crying wolf. There were even calls to have him fired. And the strange thing was, it wasn't really what he said, but that he said it at all.

HANSEN: They said if there were a secret ballot, we would probably agree that the global warming is there. But we don't like a scientist stepping out and saying that in public.

RAZ: And even though James Hansen was one of the few scientists to speak out on this issue, in the years after his testimony, the body of overwhelming scientific evidence around climate change obviously grew.

(SOUNDBITE OF TED TALK)

HANSEN: By 15 years later, evidence of global warming was much stronger. Most of the things mentioned in our 1981 paper were facts. I had the privilege to speak twice to the president's climate task force, but energy policies continued to focus on finding more fossil fuels. By then, we had two grandchildren - Sophie and Connor. I decided that I did not want them in the future to say opah understood what was happening, but he didn't make it clear. So I decided to give a public talk criticizing the lack of an appropriate energy policy.

I gave the talk at the University of Iowa in 2004 and at that 2005 meeting of the American Geophysical Union. This led to calls from the Whitehouse to NASA headquarters, and I was told that I could not give any talks or speak with the media without prior explicit approval. After I informed The New York Times about these restrictions, NASA was forced to end the censorship. How did I get dragged deeper and deeper into an attempt to communicate the gravity and the urgency of this situation? More grandchildren helped me along. Jake is a super positive, enthusiastic boy. Here at age 2 and a half years, he thinks he can protect his two and a half day old little sister. It would be immoral to leave these young people with the climate system spiraling out of control.

So now you know what I know that is moving me to sound this alarm. Imagine a giant asteroid on a direct collision course with Earth. That is the equivalent of what we face now, yet we dither taking no action to divert the asteroid. If we'd started in 2005, it would have required emission reductions of 3 percent per year to restore planetary energy balance and stabilize climate this century. If we start next year, it is 6 percent per year. If we wait 10 years, it is 15 percent per year - extremely difficult and expensive, perhaps, impossible. But we aren't even starting.

RAZ: Why do you think it's important for scientists to speak out?

HANSEN: Because scientists are trained to be objective, and that's the critical factor. And it's a difficulty I have with both political parties because their decisions are influenced so much by their politics and other things. So I think the objectivity of science is really needed in issues like this.

RAZ: So what are the consequences if if scientists don't speak up?

HANSEN: Well I think the greatest threat that civilization faces - because if you wait too long, the system can be out of control. With regard to ice sheets and sea level rise, there's practically no way to stop it. And it's amazing how many of our large cities in the world - more than half - are located on coastlines. The migration that would be forced by large sea level rise from Bangladesh in the Netherlands and Florida - so we really can't let that happen. And that's the big danger that we may lock that in. So I did have to speak out.

RAZ: Dr. James Hansen - he retired from NASA after 32 years. He now heads up the Climate Science Awareness and Solutions program at Columbia University's Earth Institute. You can find his full talk at ted.com.