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Earth's Melting Glaciers Captured in Stunning Before-and-After Images

If you don't agree with 97 percent of climate scientists that climate change is real, you should at least believe your own eyes.

The Earth's rapidly rising temperatures has dramatically transformed our landscapes, as you can see quite clearly in these vivid photos of the world's melting glaciers.

Retreat of the Columbia Glacier, Alaska, USA, by ~6.5 km between 2009 and 2015. Credit: James Balog and the Extreme Ice Survey

The photos appeared in the new paper "Savor the Cryosphere," published in the peer-reviewed GSA Today, a publication of the Geological Society of America. The cryosphere is the Earth's frozen waters.

"We have unretouched photographic evidence of glaciers melting all around the globe," co-author Gregory Baker, adjunct professor of geology at the University of Kansas, said.

"That includes the ice sheets of Greenland and Antarctica—they're reduced in size. These aren't fancy computer models or satellite images where you'd have to make all kinds of corrections for the atmosphere. These are simply photos, some taken up to 100 years ago, and my co-authors went back and reacquired photos at many of these locations. So it's just straightforward proof of large-scale ice loss around the globe."

Baker's research career centers on geophysical imaging of Earth's subsurface and geoscience education.

Stein Glacier, Switzerland, retreat of ~550 m from 2006 to 2015. Credit: James Balog and the Extreme Ice Survey

Photographer James Balog, who was featured in the Emmy Award winning climate change documentary, Chasing Ice, contributed photographs from the Extreme-Ice Survey.

Other co-authors of the paper include Richard Alley, an American geologist who was invited to testify about climate change by Vice President Al Gore; Patrick Burkhart of Slippery Rock University; Lonnie Thompson of the Byrd Polar Research Center at Ohio State University; and Paul Baldauf of Nova Southeastern University also contributed to the paper.

The team hopes the paper will raise awareness about the world's melting glaciers.

"We have all heard of the impact of melting ice on sea level rise, but the public also need to be aware that places around the world depend on glaciers for their water and are going to come under increasing stress, and we already see how water shortages lead to all kinds of conflict," Baker said.

"The other critical point often overlooked is that when glaciers melt we're losing these scientific archive records of past climate change at specific locations around the Earth, as if someone came in and threw away all your family photos."

Solheimajokull, Iceland, retreat of ~625 m from 2007 to 2015. Credit: James Balog and the Extreme Ice Survey

"Glacier ice contains fingerprint evidence of past climate and past biology, trapped within the ice," Baker continued.

“Analyzing ice cores is one of the best ways to analyze carbon dioxide in the past, and they contain pollen we can look at to see what kind of plant systems may have been around. All of this information has been captured in glaciers over hundreds of thousands of years, and sometimes longer—Greenland and Antarctica cover perhaps up to a million years. The more that glacial ice melts, the more we're erasing these historical archives that we may not have measured yet in some remote glaciers, or deep in ice caps, that can tell us the history of the Earth that will be gone forever."

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A coastal glacier in southern Greenland mirrored in the sea. Photo credit: Claire Rowland via Flickr

Greenland's Coastal Glaciers in Terminal Decline

By Tim Radford

By the century's end, some of Greenland's ice will have vanished forever.

New research shows that the coastal glaciers and ice caps are melting faster than ever before and may have already reached the point of no return two decades ago. That is because they have passed the stage at which they can refreeze their own meltwater.

These peripheral glaciers and icecaps cover an estimated 100,000 square kilometers of the island. And when they have gone, the world's oceans will have risen by four centimeters.

Body of Greenland ice

But scientists reporting in Nature Communications journal said most of the Greenland ice—the biggest body of ice in the northern hemisphere—is still safe. Were all of its ice to melt, sea levels would rise by at least seven meters.

"Higher altitudes are colder, so the highest ice caps are still relatively healthy at the moment," said study leader Brice Noël, a PhD student of polar glaciology and Arctic climate modeling at the University of Utrecht in the Netherlands.

"However, we see melting occur higher and higher. That's a big problem, because that 'melting line' is moving towards the altitude where most of the ice mass is.

"The main ice sheet in the interior of Greenland is much more elevated and isn't doing too bad yet. But we can already see an increase in the altitude of the 'melting line' there as well."

The coastal research concentrated on the mechanics of ice loss. Normally, glaciers and ice caps grow because summer meltwater drains through into the deeper frozen snow and freezes again. The icecap retains its mass and even increases.

But 20 years ago, the firn, or older snow, became saturated, freezing right through, and more summer meltwater now runs to the sea. The rate of increase varies from 17 to 74 percent and the icecaps each year are losing three times the mass loss measured in 1997.

Concern about Greenland ice and glaciers being in retreat is not new. In fact, glaciers in both hemispheres are observed to be in retreat, and the Geological Society of America has just published telltale imagery and an analysis based on observations of more than 5,200 glaciers in 19 regions around the world, showing that the loss of ice mass this century is without precedent.

So Greenland's glaciers are just part of a bigger picture. But since Greenland is home to the second largest volume of ice on the planet, what happens there concerns the entire world.

Testimony to climate change

Researchers observed years ago that the rivers of Greenland ice are in spate and rates of melting are thought likely to accelerate. The latest report is another piece of testimony to climate change in the far north.

"These peripheral glaciers and ice caps can be thought of as colonies of ice that are in rapid decline, many of which will likely disappear in the near future," said Ian Howat, a glaciologist at Ohio State University in the U.S. and a co-author of the report.

"In that sense, you could say that they're 'doomed.' However, the ice sheet itself is still not 'doomed' in the same way. The vast interior ice sheet is more climatologically isolated than the surrounding glaciers and ice caps.

"Also, since this 'tipping point' was reached in the late 1990s before warming really took off, it indicates that these peripheral glaciers are very sensitive and, potentially, ephemeral relative to the timescales of response of the ice sheet."

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A team from Rutgers University and the University of Georgia, led by Asa Rennermalm of Rutgers, measures meltwater runoff from the ice sheet margin in Greenland during summer 2013. Photo credit: Asa Rennermalm/Rutgers University

Greenland's Coastal Glaciers Rapidly Withering Away

Greenland's icy coastlines are withering away at a rapid pace. With ever rising temperatures in the region, scientists fear the glaciers may never grow back.

A team from Ohio State University discovered that about 20 years ago, melting on the island reached a tipping point. In this event, a layer of old snow called the firn, was frozen over and the ice sheet growth was stunted. This caused the new growth on the coastlines to halt. Combined with rising temperatures of the sea, the ice has been melting away in large sectors. At the rate it's going, the team said there will be a 1.5 inch increase in global sea level rise by 2100.

According to the study:

The find is important because it reveals exactly why the most vulnerable parts of Greenland ice are melting so quickly: the deep snow layer that normally captures coastal meltwater was filled to capacity in 1997. That layer of snow and meltwater has since frozen solid, so that all new meltwater flows over it and out to sea.

Though these findings are bad news, the researchers said there is no "immediate cause for panic." The Greenland Ice Sheet—the second largest ice cache in the world—is relatively intact. Associate professor at Ohio State, and co-author of the study Ian Howat, said the outer layers of ice contribute a small portion to the greater sheet, and that their melting may even be ephemeral, or seasonal to some degree.

"Since this 'tipping point' was reached in the late 90's before warming really took off, it indicates that these peripheral glaciers are very sensitive and, potentially, ephemeral relative to the timescales of response of the ice sheet," said Howat.

The areas in red are most at risk of being lost.

Though the entire coastline is not at risk, if it were to melt away, we'd see an uptake of a few inches in sea level. To put that in terms of the greater ice sheet, if the entire entity melted, we'd see a rise of 24 feet in total.

"These peripheral glaciers and ice caps can be thought of as colonies of ice that are in rapid decline, many of which will likely disappear in the near future," said Howat. "In that sense, you could say that they're 'doomed.' However, the ice sheet itself is still not 'doomed' in the same way. The vast interior ice sheet is more climatologically isolated than the surrounding glaciers and ice caps."

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Photo credit: NASA / Kathryn Hansen

Sea Ice Falls to Record Lows in Both the Arctic and Antarctic

By Roz Pidcock

The Arctic and Antarctic have experienced record lows in sea ice extent so far in 2017, according to the latest data from the U.S. National Snow and Ice Data Center (NSIDC).

At about this time each year, the Antarctic reaches its lowest extent for the year while the Arctic reaches its highest. The new satellite data, released Wednesday, confirms that there is less sea ice globally than at any time in the entire 38-year satellite record.

The NSIDC doesn't usually release data for both poles simultaneously, but has done so this time because of what scientists have dubbed an "exceptional" year in 2017.

The news comes as the World Meteorological Organization confirmed this week that 2016 "made history" with record high global temperatures and low sea ice. Many of last year's extreme conditions have continued into 2017, the report noted.

Arctic Low

With just 14.42m square kilometers on March 7, this year's winter maximum in the Arctic ranks as the smallest in the satellite record, for the third year in a row.

This year's maximum extent is 1.22 million square kilometers below the 1981 to 2010 average maximum of 15.64 million square kilometers, NSIDC confirmed Wednesday.

Record low sea ice extent in February continued a string of records over the winter months, from October through February. A "heatwave" in mid-November caused some parts of the Arctic to be 15ºC warmer than usual, for example.

Carbon Brief

The Arctic winter maximum has been shrinking by about three percent per decade. The decline is much faster for the summer minimum in September, at more like 13 percent per decade. Recent research shows up to two-thirds of the drop is a direct result of human activity.

Ice lost from the Arctic can have consequences much further afield, as a new WMO report explained:

"Scientific research indicates that changes in the Arctic and melting sea ice is leading to a shift in wider oceanic and atmospheric circulation patterns. This is affecting weather in other parts of the world because of waves in the jet stream—the fast-moving band of air which helps regulate temperatures."

As we enter 2017's summer melt season, Arctic sea ice looks vulnerable. This is especially so, given that the latest sea ice thickness observations from the CryoSat-2 satellite show very thin ice in a number of regions, said Zack Labe, a PhD student studying sea ice at the University of California. That said, it's too soon to tell if we'll see a record low minimum come September, he told Carbon Brief:

"Weather has a big role in the summer melt season, so speculations are challenging as to whether 2017 will be a new record minimum."

Arctic sea ice extent for March 7 was 14.42 million square kilometers. The orange line shows the 1981 to 2010 median extent for that day.U.S. National Snow and Ice Data Center

Greenland

While the behavior of Arctic sea ice tends to attract the biggest headlines, the continent of Greenland has been experiencing unusual weather this winter, too.

Despite some periods of extreme cold, this winter has been much warmer than average, according to Polar Portal, a website run by Danish researchers. A succession of heavy storms since October dumped more snow than usual on the eastern and southern parts of ice sheet, the scientists explained:

"The accumulation season got off to a flying start in October, when a series of large storms hit the east coast of Greenland, dropping 264mm of rain in the main town of Tasiilaq in 25 days, compared to the average for October of 83mm for the whole of October."

Top: Map of ice mass lost (red) and gained (blue) from the surface of Greenland through snowfall between Sept. 1 2016 and March 20 (in mm water equivalent) Bottom: Change in surface ice mass during winter 2016/17 compared to previous years. Danish Meteorological Institute

But while some claim this extra snowfall over winter means Greenland ice is at "record high" levels, this ignores a much bigger part of the picture. Icebergs "calving" off the ice sheet and into the ocean account for much bigger losses, explained Dr. Ruth Mottram, a researcher at the Danish Meteorological Institute. She told Carbon Brief:

"Over the last decade, Greenland has lost around 200-300bn tonnes (gigatonnes, Gt) of ice each year; the extra snowfall we estimate from our models is about 150Gt. So it's not at all balancing what is lost by melting and calving in a typical year."

The summer months—June, July and August—are the most important for the ice sheet, so it's important not to read too much into heavy snowfall over the winter season, Mottram added.

"Exceptional Year" in the Antarctic

Meanwhile, at the other end of the planet, Antarctic sea ice has been experiencing its minimum extent for the year.

With 2.11m square kilometers of ice, this year's low marks an all-time record low for the satellite era. Reached on March 3, the summer minimum caps off an unusually vigorous melt season, with new records set in every month since November.

Carbon Brief

How does 2017 compare to previous years? Natural fluctuations play a big role in Antarctic climate, causing swings in sea ice extent from year to year. Dr. Mark Brandon, a polar oceanographer at the Open University, told Carbon Brief:

"Just a few years ago the Antarctic sea ice extent was breaking records as being relatively high, but this year it has shown record-breaking lows for several months."

The Antarctic's "exceptional year" in 2017 could even be a hangover from the powerful El Niño the world recently experienced, said Brandon:

"A pattern of air pressure that determines the wind circulation in the high southern latitudes called the Southern Annular Mode switched from positive to negative in late 2016 and this may be linked to the large El Nino of 2014-16."

This switch made the ice "more mobile and likely led to the relatively early Antarctic spring," explained Brandon.

Antarctic sea ice extent for March 3 was 2.11 million square kilometers. The orange line shows the 1981 to 2010 median extent for that day.U.S. National Snow and Ice Data Center

Having passed the summer minimum, sea ice has started growing again. But scientists will be keeping a close eye in coming months to see how the ice fares over the winter freeze up season, explained Prof. John Turner, a climatologist at the British Antarctic Survey. He told Carbon Brief:

"The rate of recovery after March 1 has been a little slow, but not too far off what we see normally. It's just that the amount of ice is about 400,000 square kilometers less than the previous minimum."

Bucking the Trend

Such low ice cover at this time of year is unusual for recent times. Satellites have, in fact, measured a slight increase in Antarctic sea ice over the past 20 years or so, despite rising global temperature. You can see this in the graph below from NSIDC.

A number of factors could be behind this somewhat counterintuitive trend, said Dr. Jonathan Day, an expert in sea-ice prediction at the University of Reading. He told Carbon Brief:

"[The upward trend in Antarctic sea ice] could be a response to human-caused climate changes, such as ozone depletion or freshening of the ocean surface due to melting of land ice, both of which may cause the ice cover to expand."

Evidence also suggests a change in winds driven by a natural cycle in the tropical Pacific Ocean could be behind recent Antarctic sea ice growth, said Day. Prof. Jerry Meehl, a scientist from the National Center for Atmospheric Research and lead author on that research, told Carbon Brief:

"The connection from the tropical Pacific to the Antarctic involves a chain reaction of linked physical processes that ends up with the winds around Antarctica affecting sea ice extent."

If natural variability has been masking the signal of human-caused climate change in the Antarctic over the satellite period, this pattern will reverse at some stage. In fact, it may already have, said Meehl. He told Carbon Brief there is evidence the Pacific cycle "switched" in 2015, which could mean we're seeing the start of a declining trend in Antarctic sea ice.

But the message from scientists is that while Antarctic sea ice appears to be bucking the trend this year, they need more than a single year before they can tell if a long-term change is afoot.

Conclusion

Overall, it has been an exceptional year for the world's ice cover. While Antarctic sea ice has thrown up a few interesting questions for polar scientists, record low levels in the Arctic for this time of year continues the persistent downward trend that characterizes the last three decades.

Reposted with permission from our media associate Carbon Brief.

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7 Stunning Images Show the Northern Lights' Winter Magic

With its Arctic climate and desolate, rocky landscape, icy Greenland isn't a typical travel destination. That is precisely what drew award-winning explorer and photographer Paul Zizka to camp out on an ice cap and capture one of Greenland's natural phenomena, the Aurora Borealis, aka Northern Lights.

Ilulissat gave us the traditional green welcome tonight. It's so good to be back in Greenland! ©Paul Zizka

Another crazy night in Greenland, as the aurora pours down onto the ice giants below.©Paul Zizka

According to NASA, "all auroras are caused by energetic particles—typically electrons—speeding down into Earth's atmosphere and colliding brilliantly with the atoms and molecules in the air." Although auroras can be spotted in an array of colors, pink and pale green lights are seen most often.

More than 80 percent of Greenland is covered by an ice cap that is almost two and a half miles thick, although it is melting 7 percent faster than previously thought. This remote nation is the world's largest island and the superb air quality may also enhance its auroras.

Heads up! A self-portrait from Greenland. ©Paul Zizka

The Aurora dances above a winter wonderland during a spectacular night in Yellowknife, Canada.©Paul Zizka

Zizka has said this job as a photographer requires a great deal of patience. "Shooting the Northern Lights almost always means waiting for your moment of magic," he explained.

As an adventurer, Zizka is drawn to "under-documented" locales. Between balmy French Polynesia and back to his hometown of Banff, Canada, landscape photography has brought him around the world. From Greenland to northern Minnesota to the "bitter cold of Northern Canada" to Iceland, Zizka has followed the trail of the Northern Lights across multiple countries, with more to come in the future. He has trips planned to Antarctica and the Faroe Islands.

Exploring the shores of Iceland as we try to take in the indescribable scene unfolding before our eyes! ©Paul Zizka

Looking back to one of my most memorable nights spent in the Canadian mountains. ©Paul Zizka

On his website, Zizka states, "I believe there is in all human beings a deep connection with the natural environment. In these times, however, that link is often obscured by the capitalistic, hectic, materialistic and anthropocentric nature of our societies. My hope is that through my photography people will rediscover the precious connection they can have with the wonders of our planet. "

To keep up with Zizka, you can read his blog or follow him on Instagram and Facebook.

A sky of magic dances above Jasper Lake in Canada during a recent Aurora show. ©Paul Zizka

Greenland Ice May Melt Quicker Than Scientists Thought

Two studies published in Nature Wednesday show seemingly contradictory visions for Greenland's past and the future of its ice sheet, but actually describe different aspects of the ice.

Meltwater on the Greenland ice sheet carved this canyon. Ian Joughin

One study finds that Greenland's ice sheet may have melted almost completely and repeatedly during the last 1.4 million years, suggesting the ice is more sensitive to warming than currently thought.

The second concluded that the ice on the very easternmost coast has been stable over a 7.5 million year period. Scientists working on both studies say that their results could be compatible: both demonstrate the volatility of the ice sheet, both show that more research is needed, and that while the majority of the island's ice has melted multiple times, the high altitude east coast has remained icy. Determining the ice sheet's response to warming is crucial, because its melting could raise global sea levels by up to 24 feet.

For a deeper dive:

Time, Gizmodo, AFP, Christian Science Monitor, US News & World Report, Scientific American, InsideClimate News, Phys.org

For more climate change and clean energy news, you can follow Climate Nexus on Twitter and Facebook, and sign up for daily Hot News.

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7 Key Scenes in Leonardo DiCaprio's Climate Film 'Before the Flood'

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

1. Prof. Jason Box

2. Prof. Michael E. Mann

3. Dr. Sunita Narain

4. Prof. Gidon Eshel

5. Elon Musk

6. President Obama

7. Dr. Piers Sellers

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.

Greenland Ice Sheet Melting 7% Faster Than Previously Thought

By Jeremy Deaton

You might know the feeling—after months of encouraging news from your bathroom scale, you discover the device is broken. The outlook on your weight-loss goal is worse than you realized.

Scientists just went through something similar, except instead of a scale, it was a system of satellites, and instead of your winter weight, it was the Greenland ice sheet.

Zachariae Isbrae, in northeast Greenland.Anders A Bjork/The Ohio State University

Researchers have been tracking Greenland's ice sheet melt by measuring the shrinking mass of the island via satellite. It now seems there was an error in measurement. A new study published in the journal Science Advances finds the ice is melting 7 percent faster than previously thought.

Scientists use satellites to map Earth's gravity field, gathering information about the distribution of mass around the globe. Earth doesn't exert gravity equally in all directions. Where there is more mass, satellites detect a stronger gravitational pull.

Using satellite data, scientists can measure various geophysical phenomena, including the melt of the Greenland ice sheet. As ice dissolves, the island loses mass and exerts a weaker gravitational pull—at least that's the idea.

An artist's rendering of NASA's Gravity Recovery and Climate Experiment satellites measuring Earth's gravity field.NASA/JPL-Caltech

In practice, it's a little more complicated. Satellites can only detect a change in mass. They can't determine how much of that mass is ice, how much is land and how much is mantle ebbing and flowing beneath the Earths' crust.

"[The system] cannot tell the difference between ice mass and rock mass," said study co-author Michael Bevis, professor of Earth sciences at Ohio State. "So, inferring the ice mass change from the total mass change requires a model of all the mass flows within the Earth."

Here's where this gets interesting.

A cross-section of Earth. The Earth's crust rests on a thick layer of mantle. Below that lies the Earth's solid core.NASA/JPL, Université Paris Diderot and the Institut de Physique du Globe de Paris

Tectonic plates are always moving. The plate under North America—including Greenland—has been traveling northwest for millions of years. Around 40 million years ago, Greenland slid over an extra hot column of partially molten rock. This hot spot softened up the crust below the island's east coast. (The hot spot now rests beneath Iceland, where it is driving all manner of volcanic activity—warming hot springs and fueling the country's geothermal power plants.)

The softening of Earth's crust beneath Greenland had consequences during the last ice age, when Greenland's ice sheet was significantly thicker. The weight of all that ice caused the island to sink into the supple crust below. When the ice age passed and the ice began to melt, the island rebounded. Mantle flowed in beneath Greenland, causing the land to rise again. It's still rising today.

You can imagine how this would interfere with satellite readings. The loss of ice is weakening Greenland's gravitational pull. At the same time, the accumulation of mantle is strengthening its gravitational pull.

One of dozens of GPS units researchers used to measure the rise of land.Dana J. Caccamise II/The Ohio State University

Scientists previously accounted for the flow of mantle, but they underestimated its effect. The study's authors used GPS technology to measure the rise of land at various points along Greenland's east coast. They discovered that mantle is gathering beneath Greenland more quickly than they had realized.

What this means is that scientists have been underestimating ice loss by 20 billion metric tons per year. More of the melting is occurring along Greenland's east coast than previously thought.

Water overflow from a lake formed from melted ice carved this 60-foot canyon into the Greenland ice sheet.Ian Joughin, University of Washington

"By refining the spatial pattern of mass loss in the world's second largest—and most unstable—ice sheet, and learning how that pattern has evolved, we are steadily increasing our understanding of ice-loss processes, which will lead to better-informed projections of sea-level rise," said Bevis.

The study has implications for Antarctica—the 800-pound gorilla of global sea-level rise. Scientist will need to deploy more GPS measurement stations at Earth's southern pole to accurately measure the flow of mantle beneath the continent and get a better reading of Antarctic ice melt.

Better data will allow scientists to predict future sea-level rise more accurately. That could prove crucial for coastal cities preparing for the impacts of climate change.

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