By Leo Hickman
Before the Flood, a new feature-length documentary presented and produced by Leonardo DiCaprio, is released in cinemas today.
The Oscar-winning actor and environmentalist has spent the past three years asking a wide variety of people around the world about climate change. His collection of interviews in the film—ranging from President Obama and the Pope through to Elon Musk and Piers Sellars—cover the science, impacts, vested interests, politics and possible solutions.
Leonardo DiCaprio visits the National Aeronautics and Space Administration Goddard Space Flight Center to discuss Earth science with Piers Sellers.NASA / Goddard/ Rebecca Roth
Carbon Brief was invited to the European premiere of Before the Flood last weekend. Before the screening in London began, DiCaprio took to the stage to introduce the film. He said:
"Before The Flood is the product of an incredible three-year journey that took place with my co-creator and director Fisher Stevens. We went to every corner of the globe to document the devastating impacts of climate change and questioned humanity's ability to reverse what maybe the most catastrophic problem mankind has ever faced. There was a lot to take on. All that we witnessed on this journey shows us that our world's climate is incredibly interconnected and that it is at urgent breaking point.
"I've been incredibly moved by so many climate change documentaries in the past, but I never felt that I saw one that articulated the science clearly to the public. I think people grasp it, but it seems something distant, far off, intangible and almost otherworldly. An individual doesn't feel like they can make an impact. The journey for me was to try and make a modern-day film about climate change. I've been studying this issue for the past 15 years, I've been watching it very closely. What's incredibly terrifying is that things are happening way ahead of the scientific projections, 15 or 20 years ago. 
"We wanted to create a film that gave people a sense of urgency, that made them understand what particular things are going to solve this problem. We bring up the issue of a carbon tax, for example, which I haven't seen in a lot of documentaries. Basically, sway a capitalist economy to try to invest in renewables, to bring less money and subsidies out of oil companies. These are the things that are really going to make a massive difference. It's gone beyond, as we talk about in the film, simple, individual actions. We need to use our vote ... We cannot afford to have political leaders out there that do not believe in modern science or the scientific method or empirical truths … We cannot afford to waste time having people in power that choose to believe in the 2 percent of the scientific community that is basically bought off by lobbyists and oil companies. They are living in the stone ages. They are living in the dark ages. We need to live in the future."
Here, Leo Hickman, Carbon Brief's editor, identifies seven key scenes in Before the Flood…
Setting the Scene
In terms of box-office draw alone, Before the Flood is the most significant film about climate change since Al Gore's An Inconvenient Truth was released a decade ago. DiCaprio has made maximum use of his global star power to bring together some of the world's leading voices and experts on climate change and package them up into 90-minute narrative which drips with urgency, insights and emotion.
It opens with a surprisingly personal monologue by DiCaprio in which he talks about the "nightmarish" painting which hung over his crib as a child. 
"I would stare at it before I went to sleep," he explained, noting some of its themes—"over-population, debauchery, exodus." 
Hieronymus Bosch's Garden of Earthly Delights was painted more than 500 years ago, but it speaks to today, he said, with its "twisted, decayed, burnt landscape." DiCaprio said the triptych's final panel shows a "paradise that's been degraded and destroyed." 
The film is named after the middle panel—Humankind before the Flood—which, he said, acts as an allegorical warning to the world of what could come next, if it fails to act on climate change.
DiCaprio then sets off around the world on his quest for answers: "I want to see exactly what is going on and how to solve it." But self-doubt looms large from the off, even after he is named by Ban Ki-moon as the UN messenger of peace on climate change.
"Try to talk to anyone about climate change and people just tune out. They might have picked the wrong guy." As DiCaprio said this, a montage plays of clips showing his media critics, such as Fox News' Sean Hannity, attacking him for his lack of scientific credentials and celebrity lifestyle.
However, DiCaprio is frank about how his fame has afforded him such a privileged perspective: "First time I heard of global warming was when I sat down one-to-one with Al Gore [in the early 2000s]. This is most important issue of our time, he said. I had no idea what he was talking about."
After viewing tar sands in Canada by helicopter—"kinda looks like Mordor"—and narwhal whales in Kangerlussuaq, Greenland, DiCaprio explained what, in his view, has changed in the time since he received Gore's climate lesson.
"Everyone was focused on small individual actions [back then]. Boiled down to simple solutions such as changing a light bulb. It's pretty clear that we are way beyond that now. Things have taken a massive turn for the worse."
The Garden of Earthly Delights, a painting by Hieronymus Bosch from 1485.Damian Michaels / Flickr
1. Prof. Jason Box
DiCaprio is helicoptered onto the Greenland ice sheet, where he meets with Jason Box, a professor at the Geological Survey of Denmark and Greenland. Box has spent many Arctic summers monitoring the stability of the ice sheet, as well as, in more recent years, the way soot from forest fires and the burning of fossil fuels has darkened the snow and, hence, the ice's reflectivity or albedo. As they both stare at a torrent of water rushing down into a moulin, Box's concern about the long-term melting trend is palpable:
"We keep finding things that aren't in the climate models. That tells me that the projections for the future are really conservative. If the climate stays at the temperature that it's been in in the last decade, Greenland is going away."
DiCaprio gently mocked Box's equipment for measuring the ice.
"This is a climate station? I was imagining a massive igloo with all kinds of scientists and experiments. It really does look like broken down pool equipment."
Then he questioned why there is a long spiral of plastic hose laying on the ice. Box explained:
"The hose went down 30 feet, but [the ice] has now melted out. Five years of melt. Hundreds of cubic kilometres of ice stored on land that has now gone into the sea."
2. Prof. Michael E. Mann
No movie is complete without the bad guys. And DiCaprio is keen to stress the role that "corporate interests" have played in spreading "disinformation" about climate change.
A cast of villains is introduced ranging from right-wing newspapers and TV networks in the U.S. through to politicians and "front groups." All seek to cast doubt on the science and, in doing so, attack climate scientists.
No scientist has been more in the crosshairs than Michael E Mann, the director of the Penn State Earth System Science Center who is best known for his famous hockey stick graph showing a recent spike in global temperatures.
Publishing that graph proved to be a huge turning point, Mann told DiCaprio:
"I set myself up for a completely different life … I was vilified … I was called a fraud. I was being attacked by Congressmen. I had death threats, which were actionable enough that the FBI had to come to my office to look at an envelope that had white powder [in it]. I've had threats made against my family. These folks know they don't have to win a legitimate scientific debate. They just need to divide the public. All of that hatred and fear is organized and funded by just a few players. Fossil fuel interests … finance a very large echo chamber of climate change denialism. They find people with very impressive looking credentials who are willing to sell those credentials to fossil fuel interests. Front groups funded by corporate interests."
DiCaprio's frustration was clear: "If I were a scientist, I would be absolutely pissed every day of my life."
Footage from Frank Capra's 1958 short film for Bell Labs, The Unchained Goddess, which explains what impact burning fossil fuels will have on the climate, plays in the background.
"We've know about this problem for decades and decades," lamented DiCaprio. "Imagine the world right now if we'd taken the science of climate change seriously back then. Since then our population has grown by five billion people and counting. The problem has become more difficult to solve."
3. Dr. Sunita Narain
After a trip to Beijing to witness the smog and speak to experts about how releasing pollution data to citizens has helped to change public attitudes, DiCaprio arrives in India.
His meeting with Sunita Narain, director of the Centre for Science and Environment, provides, arguably, the key scene of the whole film. They discuss the sweetspot of the climate conundrum: How do developing nations with fast-rising populations raise standards of living for all without emitting vast volumes of greenhouse gases?
"We are a country where energy access is as much a challenge as climate change," said Narain. "We need to make sure that every Indian has access to energy."
DiCaprio mulled on that: "From what I understand, there are 300 million people without power in India. That's equivalent to the entire population of the United States."
As footage shows women in the village of Kheladi in Haryana burning uplas (cowdung cakes), Narain passionately lays out India's predicament:
Sunita Narain: Coal is cheap, whether you or I like it or not. You have to think of it from this point of view. You created the problem in the past. We will create it in the future. We have 700m household using biomass to cook. If those households move to coal, there'll be that much more use of fossil fuels. Then the entire world is fried. If anyone tells you that the world's poor should move to solar and why do they have to make the mistakes we have made … I hear this from American NGOs all the time. I'm like, wow. I mean, if it was that easy, I would really have liked the U.S. to move to solar. But you haven't. Let's put our money where our mouth is.
Leonardo DiCaprio: We have to practice what we preach. Absolutely.
Sunita Narain: I'm sorry to say this and I know you're American, so please don't take this the wrong way, but your consumption is really going to put a hole in the planet. I think that's the conversation we need to have. I'll show you charts from this perspective. [Shows page from a book]. Electricity consumed by one American at home is equivalent to 1.5 citizens of France, 2.2 citizens of Japan and 10 citizens of China, 34 of India and 61 of Nigeria. Why? Because you're building bigger, you're building more and using much more than before. The fact is we need to put the issue of lifestyle and consumption at the centre of climate negotiations.
Leonardo DiCaprio: Look, there's no way I don't agree with you. Absolutely correct. Yes, it's a very difficult argument to present to Americans that we need to change our lifestyle and I would probably argue that it's not going to happen. If we want to solve the climate crisis on, hopefully, that renewables like solar and wind will become cheaper and cheaper as more money is funneled into them and we invest into them, and, ultimately, we will solve that problem. But I … [Narain shakes her head]. You are shaking your head, obviously…
Sunita Narain: I'm shaking my head Indian style, which means "no." Who will invest? Let's be real about this. Who will invest? And how will they invest? We are doing more investment into solar today. China is doing much more investment in solar today than the U.S. is. What is the U.S. doing which the rest of the world can learn from? You are a fossil-addicted country, but if you are seriously disengaging, that's something for us to learn from. And it's leadership that we can hold up to our government and say if the U.S. is doing—and the U.S. is doing it—then, despite all the pressures, then we can do it as well … But it's just not happening. People like us, we are rich enough to withstand the first hit of climate change. But it's the poor of India, it's the poor of Africa, the poor of Bangladesh, who are impacted today in what I believe are the first tides of climate change … We need countries to believe that climate change is real and it is urgent. It's not a figment of their imagination
The scene concludes with DiCaprio musing on his conversation with Narain:
"There's no doubt we have all benefitted from fossil fuels. I know I have. My footprint is probably a lot bigger than most people's. And there are times when I question what is the right thing to do. What actions should we be taking? There are over a billion people out there without electricity. They want lights. They want heat. They want the lifestyle that we've had in the United States for the last hundred years. If we are going to solve this problem, we all have a responsibility to set an example. And, more than that, help the developing world to transition before it's too late."
4. Prof. Gidon Eshel
It is well known that DiCaprio has donated a significant proportion of his wealth and time to various habitat conservation projects, notably focused on oceans and tropical forests. So it isn't a surprise that he visits such locations in Before the Flood.
He views dead coral with marine biologist Jeremy Jackson. ("We're pushing this system really hard"). He flies over Sumatran forests being cleared by palm oil plantations with HAkA's Farwiza Farhan. ("I've never seen anything like this"). He feeds baby orangutans at a rescue center in the Mount Leuser National Park with Dr. Ian Singleton. ("They are refugees from the burning forest").
The message is clear. Lifestyle choices are damaging these carbon-absorbing habitats. Boycott companies which use palm oil to make their products, urges DiCaprio. Switch from eating beef to chicken.
This particular suggestion is put forward by the next person DiCaprio visits. Gidon Eshel, a professor of environmental science and physics at Bard College in New York, was the lead author of a study published in 2014 in the Proceedings of the National Academy of Sciences. It made headlines around the world and found that beef is about 10 times more damaging to the environment than any other form of livestock. Eshel said:
"Of all the reasons for tropical deforestation, the foremost is beef. Beef is one of the most inefficient use of resources on the planet. In the U.S., 47 percent of land is used for food production and, of that, the lion's share is just to grow feed for cattle. The things that we actually eat—fruit, vegetables, nuts—it's a percent. Most importantly, cows produce methane. And methane is a powerful greenhouse gas … About 10-12 percent of total U.S. emissions is due to beef. It's staggering … Maybe not everyone is ready to eat tofu 24/7. I get that. But even if you just have to have some flesh between your teeth, if you switch to chicken, you will have eliminated 80 percent of what you emit, depending on where you are coming from."
5. Elon Musk
DiCaprio in now looking out across Los Angeles from a vantage point up in the Hollywood hills.
"Every single light that you see has to be completely different—has to come from a new power source. We need to build all those things differently. All the cars that are on the road need to be different. This is one city. If you zoom out to a map of the world at night, you see electrification all over the world. And we're fighting powerful fossil fuel interests who basically want to keep doing business as usual. How are we possibly going to turn all this around?"
Next he is in the Nevadan desert visiting the "gigafactory," the latest project of Tesla founder Elon Musk. Once at full operation by 2020, the vast factory aims to be producing annually 500,000 electric vehicles and batteries/cells equal to 85 GWh/yr. Musk explains why this could be a game-changer:
Elon Musk: What would it take to transition the whole world to sustainable energy? What kind of throughput would you actually need? You need a hundred gigafactories.
Leonardo DiCaprio: A hundred of these?
Elon Musk: A hundred. Yes.
Leonardo DiCaprio: That would make the United States…
Elon Musk: No, the whole world.
Leonardo DiCaprio: The whole world?!
Elon Musk: The whole world.
Leonardo DiCaprio: That's it?! That sounds manageable.
Elon Musk: If all the big companies do this then we can accelerate the transition and if governments can set the rules in favour of sustainable energy, then we can get there really quickly. But it's really fundamental: unless they put a price on carbon…
Leonardo DiCaprio: … Then we are never going to be able to make the transition in time, right?
Elon Musk: Only way to do that is through a carbon tax.
[Carbon Brief has asked Tesla to explain how Musk arrived at this "100 gigafactory" claim. This article will be updated, if a reply is received].
To drive this point home, DiCaprio then speaks to Gregory Mankiw, a Harvard economics professor, who has long argued for a carbon tax. ("Let me get this straight, you're a Republican who wants more taxes?") During a "call to action" segment at the end of the film before the credits roll, a link to Carbotax.org is shown.
6. Barack Obama
When you're Leonardo DiCaprio you can request a meeting with anyone on the planet. Which other filmmaker could include personal conversations with the U.S. president, the Pope and the UN secretary general in one film?
However, given the imminent entry into force of the Paris agreement on climate change, it is DiCaprio's exchange with Barack Obama at the White House which provides the most insight.
Barack Obama: [Paris] creates the architecture. I was happy with that. The targets set in Paris are nowhere near enough, compared to what the scientists tell us we need to solve this problem. But if we can use the next 20 years to apply existing technologies to reduce carbon emissions and then start slowly turning up the dials as new technologies come online and we have more and more ambitious targets each year, then we're not going to completely reverse the warming that now is inevitable, but we could stop it before it becomes catastrophic … Even if someone came in [to the White House] denying climate science, reality has a way of hitting you on the nose if you're not paying attention and I think the public is starting to realize the science, in part because it is indisputable.
Leonardo DiCaprio: You have access to information. What makes you terrified?
Barack Obama: A huge proportion of the world's population lives near oceans. If they start moving, then you start seeing scarce resources are subject to competition between populations. This is the reason the Pentagon has said this is a national security issue. And this is in addition to the sadness I would feel if my kids could never see a glacier the way that I did when I went up to Alaska. I want them to see the same things that I saw when I was growing up.
7. Dr. Piers Sellers
There are very few people who can say they've had the privilege of being able to look down at the Earth from space. Piers Sellers, the British-born astronaut, spent a total of 35 days in orbit in the 1990s on three separate flights aboard the space shuttle. But back on Earth, he has spent much of his professional life modeling the climate system at NASA's Goddard Space Flight Center in Maryland. Earlier this year, he wrote in theNew York Times about how being diagnosed with terminal cancer has sharpened his thinking on climate change.
Sitting in front of a huge screen showing NASA visualizations of the Earth's climate in motion, Sellers explains to DiCaprio how he views the current changes to the climate as a scientist.
Dr. Piers Sellers: I realized that, as the science community, we have not done the best job, frankly, of communicating this threat to the public. When you go up there and see it with your own eye, you see how thin the world's atmosphere is. Tiny little onion skin around the Earth … [Sellers shows a visualization]. Here's an example of one thing we can see—ocean surface temperature, as measured from space. You can see the poles melting.
Leonardo DiCaprio: Wow.
Dr. Piers Sellers: This is the way to do it, man. This is the way to really see what's going on. This is the Gulf Stream. Look at this. This is the motion of the ocean.
Leonardo DiCaprio: This is like a great piece of art.
Dr. Piers Sellers: It is, isn't it? The biggest impact will be here. [Sellers points].
Leonardo DiCaprio: In the Gulf Stream.
Dr. Piers Sellers: This current … the dumping of ice off Greenland could stop this conveyor belt and the Gulf Stream would slow down and stop its transport of heat from here to there and then Europe would get cold toes because there is a lot of heat transport from across the tropics, across the north Atlantic that keeps Europe warm.
Leonardo DiCaprio: Europe would get colder? A big misconception with climate change is that everything gets warmer.
Dr. Piers Sellers: And here's the most advanced precipitation satellite in the world. It's very important, because we think the biggest impact from climate change is the moving of the precipitation belts from the equator to further out. We're already seeing more persistent drought…
Leonardo DiCaprio: …more drought in places that are already too hot?
Dr. Piers Sellers: Yes. And there are a lot of papers written in the States and elsewhere about how that same drought has help to fuel conflict in the Syrian civil war, Darfur, Sudan, all these places that are short of water and short of food.
Leonardo DiCaprio: Is just here or across the whole planet?
Dr. Piers Sellers: We are expecting elsewhere. Bits of India. In the U.S., in Oklahoma, the Dust Bowl region, we expect that to be much, much drier over the next few decades.
Leonardo DiCaprio: Oh my god. And what about my home state of California?
Dr. Piers Sellers: Not looking great, I'm afraid. Our models predicted persistent drought in the Dust Bowl and here 50 years from now. But we're just seeing the worst drought in 900 years here right now, so it's coming a bit earlier than we thought. We're talking about this happening over the period of a few decades…
Leonardo DiCaprio: This is not great news.
Dr. Piers Sellers: People get confused about the issue, but the facts are crystal clear—the ice is melting, the Earth is warming, the sea level is rising—those are facts. Rather than being, "Oh my god, this is helpless", say, "Ok, this is the problem, let's be realistic and let's find a way out of it". And there are ways out of it. If we stopped burning fossil fuels right now, the planet would still keep warming for a little while before cooling off again.
Leonardo DiCaprio: Would that Arctic ice start to then increase again?
Dr. Piers Sellers: Once the cooling started, yeah.
Leonardo DiCaprio: So there really is a possibility to repair this trajectory that we're on? Interesting.
Dr. Piers Sellers: Yeah. There's hope … I'm basically an optimistic person. I really do have faith in people. And I think once people come out of the fog of confusion on this issue and the uncertainty on this issue and realistically appreciate it on some level as a threat, and are informed on some level on what the best action is to do to deal with it, they'll get on and do it and what seemed almost impossible to deal with becomes possible.
Before the Flood opens in cinemas on Oct. 21 and will be broadcast on the National Geographic Channel on Oct. 30.
Reposted with permission from our media associate Carbon Brief.