BROOKE GLADSTONE:  This is On the Media. I’m Brooke Gladstone.

BOB GARFIELD:  And I’m Bob Garfield.  Journalistic ethics have long tabooed rushing to judgment about the cause of this tornado or that flash flood. Politicians too have flinched from drawing

a straight line from natural disasters to climate change. Here’s a press conference with President Obama in 2012.

  [CLIP]:

MARK LANDLER/THE NEW YORK TIMES:  Tomorrow you're going up to New York City where you’re going to see people who are still suffering the effects of Hurricane Sandy, which many people say is further evidence of how a warming globe is changing our weather. What specifically do you plan to do in a second term to tackle the issue of climate change?

PRESIDENT OBAMA:  As you know, Mark, we can’t attribute any particular weather event to climate change.

  [END CLIP]

BOB GARFIELD:  But has that abundance of caution mutated into a sort of incautious denialism, because when President Obama made that claim the science connecting the weather and the climate, called extreme weather attribution, already had been around for almost a decade. Certainly, in the ensuing four years, that connection has gotten a lot clearer.

HEIDI CULLEN:  This past March, the National Academy of Sciences released a consensus statement on the state of extreme event attribution, and, and they made it very clear that it is now possible to attribute individual events to climate change.

BOB GARFIELD:  Heidi Cullen is the chief scientist at Climate Central, an organization devoted to communicating the science of climate change to the public. For years, she worked at The Weather Channel and whenever something nasty happened people would ask her if the cause was climate change. And she – hemmed and hawed.

HEIDI CULLEN:  Yes, I did have to hedge because in the early days – this is 2003, 2004 – the answer was, well, you can’t attribute any individual event to climate change. And it felt pretty bad, like I really wanted to be far more helpful than I was able to be. And I’ll never forget when the very first extreme event attribution analysis came out, looking at the European heat wave of 2003, and I finally had something specific and solid to say about an individual event that impacted – I mean, it cost the lives of over 30,000 people in Europe, and we found a very strong climate change fingerprint in that event.

BOB GARFIELD:  Just to be clear, no individual storm can exactly be traced to climate change. There's no smoking gun.

HEIDI CULLEN:  Just like with cigarette smoking and lung cancer, and I can't say that that cigarette is what caused someone's lung cancer, the same thing with climate change and extreme weather. But what we can say is that climate change increased the likelihood or increased the intensity of a specific weather event. You can make a definitive quantitative statement about what role climate change may or may not have played in an individual weather event.

BOB GARFIELD:  What’s the methodology?

HEIDI CULLEN:  It’s fairly straightforward. A lot of the techniques actually come from epidemiology. So to go back to the cigarette smoking and lung cancer analysis, you look at what probability can be explained by a given causal factor. And so, with extreme event attribution what climate scientists do is look at, is there a trend, for example? Are there increasing heat waves in this particular area? And then we use climate models to essentially recreate that event.

We create a model that is the world as we know it today and then we create what we call a counterfactual, the world as it would have been without us and all of our global warming pollution. And then we look at the statistics and we say, okay, how likely was an event like this epic flood that hit Louisiana, how likely was that event in the world we live in now, with all of the additional greenhouse gases we’ve put into it versus that event in the past in a completely natural world, if you will? And that's what allows us to do what we call an attribution to climate change or carbon pollution, essentially.

BOB GARFIELD:  What other recent weather events could you take to court with your comparative models and get a conviction beyond a reasonable doubt?

HEIDI CULLEN:  Heat waves, cold waves, heavy rainfall events, floods and droughts. And then, on the far end, I would say that there's still a lot of work to be done trying to really untangle, say, tornados. That’s really at the far end of our capabilities. And I’d say that something like hurricane attribution, that's really at the cutting edge right now and there are some really good groups working on it.

BOB GARFIELD:  We’re talking about the epidemiology of weather. Give me a notion of how good a case you can make. What is the scale of risk that we can now measure?

HEIDI CULLEN:  Well, just as one example that is just really profound, an analysis was done by some colleagues at the University of Melbourne looking at the recent bleaching of the Great Barrier Reef. And what they found was that climate change made that event 175 times more likely. You're basically moving into territory where that event wouldn’t have happened in the absence of global warming. That’s a pretty profound statement.

BOB GARFIELD:  So if we’re back in court, you can get the verdict from the jury you’re looking for.

HEIDI CULLEN:  The evidentiary standards of lawyers are beyond a reasonable doubt. That’s 51%. So yeah, I think 175 times more likely is the winner.

BOB GARFIELD:  It makes me wonder whether the language that we tend to associate with extreme weather, for example, the term “natural disaster,” is that the right term anymore?

HEIDI CULLEN:  I think that is the beginning of a really long [LAUGHS] and important conversation. For the longest time, we have viewed our environment and the incredible weather that it produces as an act of God, if you will. And I think that for myself and the colleagues that I work with on rapid attribution analyses, it’s to really help provide that context, to say, no, if your home got flooded the third time in a row, it's not just because you're unlucky; it's because the system has changed, the odds have increased. And we need to have a conversation about how to deal with the changing nature of these risks.

BOB GARFIELD:  Now, weather modeling is not new. How is it that it's taken so long for climate scientists to make this case?

HEIDI CULLEN:  For a very long time, the scientific community was focused on the global scale. It was the fact that our planet has warmed up 1.8 degrees Fahrenheit over the past century over the entire globe. And I think as our computer models got better, as we were able to run them more quickly, we were then able to narrow the time and the space with which we looked at events. It wasn't just temperature or rainfall over the entire earth. It was this specific event in this specific place.

BOB GARFIELD:  The premise of this conversation is that the media have been, as a group, reluctant to make connections, in reporting about severe weather, with climate change. Are we guilty of malpractice? Should we have been onto extreme weather attribution long before this?

HEIDI CULLEN:  I often think about the 2008 economic meltdown and the fact that leading up to that crisis there was a ton of reporting where we talked about the ups and downs of the stock market and how the housing market was booming, and that broader economic context was missing. And so, when the crash actually happened, there was a lot of people who asked, God, why didn't we know about this sooner?

And I, I feel like maybe that's the moment we're at right now, but I do think that there is a true opportunity and, and, in fact, a true responsibility for the media to connect the dots better because 20 years from now when things really begin to melt down, the question is going to be, why didn't anyone tell me about this sooner? This science of extreme event attribution is a way to help people finally see what climate change is doing to them and their families and their communities right now.

BOB GARFIELD:  Heidi, thank you very much.

HEIDI CULLEN:  Thank you, Bob.

BOB GARFIELD:  Heidi Cullen is the chief scientist at Climate Central.