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Photo credit: NASA / Kathryn Hansen

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.

Photo credit: iStock

By Roz Pidcock

The buildup of heat-trapping greenhouse gases is warming the upper ocean four times faster than during the period 1960-1990, according to new research.

The paper, published March 10 in the journal Science Advances, is the latest effort to piece together current and historical measurements from ships, self-propelled floats, satellites and even seals to get a global picture of how the oceans are faring under rising temperatures.

Since the 1990s, more heat is finding its way to the deep ocean and there has been no change of pace in ocean warming since 1998, compared with the previous decade, the paper notes.

The study marks a step forward, but the authors said they are concerned about the future of ocean science, given the political climate in the U.S. Dr. John Abraham, professor of thermal sciences at the University of St. Thomas in Minnesota and co-author on the paper, told Carbon Brief:

"We are seeing dramatic cuts planned for climate science. There is every reason to expect these cuts will include ocean-sensing systems."

Big Role to Play

Approximately 93 percent of the heat captured by greenhouse gases in the atmosphere ends up in the ocean. The remaining 7 percent heats the atmosphere and the land and causes ice to melt.

This means it is only by measuring the oceans that scientists can tell how fast the planet is heating and how much it will heat in the future, Abraham told Carbon Brief:

"If you want to know about global warming, you really have to understand ocean warming."

Rosamund Pearce / Carbon Brief

Completing the Picture

But accurately working out how quickly the oceans are warming is a difficult task, partly because of gaps in the historical data. Abraham told Carbon Brief:

"Measuring the oceans is challenging because you need enough sensors, in enough locations, for a long enough time to get a picture of the climate."

Early observations were typically done by commercial and scientific research ships, which means they were limited to developed countries and along shipping routes, the paper explains.

In the 1990s, the World Ocean Circulation Experiment greatly expanded the coverage of ocean temperature records. Since 1992, satellites have helped to infer ocean warming from changes in the height of the sea surface, since seawater expands as it warms.

The quality of ocean measurements stepped up a gear after 2005, with the introduction of ARGO floats, a network of nearly 4,000 free-floating buoys measuring temperature in the top 2,000m of the world's oceans.

Map showing the global coverage of the ARGO network and positions of floats that have delivered data within the last 30 days.ARGO

To get a global picture of what's happening across the huge expanse of global ocean, scientists combine measurements from the ARGO network, ship-based observation systems, buoys tethered to the seafloor and even temperature sensors attached to the heads of seals.

While there is a wealth of data post-2005, there are gaps before then that need filling in.

Scientists typically do this by making a best guess based on measurements taken at other locations nearby. The new study updates this approach, said Dr. Lijing Cheng, associate professor at the Chinese Academy of Sciences and lead author on the paper. He told Carbon Brief:

"Our study offers a new method to solve these problems."

Instead of including stations within 800km of the missing data point, as other studies have, the authors extends this to 2,500km to account for the often greater distance between historical stations. This left fewer gaps unfilled and more ocean accounted for, the paper explains.

The authors were also able to correct for past studies that may have underestimated warming by comparing good data from the ARGO era with sparse observations for the same region taken in the 1960s or 1970s. Prof. Kevin Trenberth, a senior scientist at the U.S. National Center for Atmospheric Research and co-author on the paper, told Carbon Brief:

"It has been amazing how much we have been able to recover in terms of information about ocean heat content from sparse past data."

The new method left the scientists with better-than-90 percent coverage of the oceans from the late 1950s to 2015 and from the sea surface all the way down to a depth of 2,000m.

Warming Signal

The study shows the oceans warmed relatively slowly before 1980 and faster since then. The black line in the graph below from the paper shows how the pace picks up after 1980.

The authors say in the paper that their new estimate is "somewhat greater" than previous reports, including the latest report from the Intergovernmental Panel on Climate Change (IPCC).

Dr. Matt Palmer, expert in sea level and ocean heat content at the UK Met Office, who wasn't involved in the study, told Carbon Brief:

"The paper represents an important refinement to our estimates of ocean heat content change … While the study does not alter our basic understanding, it does suggest that IPCC AR5 reported rates of ocean warming were underestimated by about 10-15%."

Increasingly sophisticated ways to keep tabs on the oceans allow scientists to pinpoint, not only how much heat enters the oceans, but also where it goes when it gets there.

The study shows the speed of warming in the upper ocean, between the surface and 700m, has quadrupled between 1960-1991 and 1992-2015 (slope of blue line, below). More strikingly, perhaps, the deep ocean (700-2000m) is warming nine times faster than in the 60s, 70s and 80s (red line).

Global ocean heat content from 1955 to 2015 for the upper ocean (blue), deep ocean (red) and both together (black). All figures are relative to the 1997-2005 average. Cheng et al., (2017)

No Slowdown

Despite what the study calls a "surge" in research into whether global temperature at the Earth's surface slowed down temporarily in the late 90s and 2000s, the paper is clear that no such change of pace has happened in the oceans. It says:

"Our studies show that there has been no slowdown in global ocean heat content change since 1998 compared with the previous decade."

Looking at solely surface temperature over a decade or so is not a reliable way of to track the rate of global climate change, said Palmer:

"Since ocean heat content continued to increase at a time when the rate of global surface temperature rise slowed down, we can infer that a large part of the 'slowdown' must have originated from ocean heat re-arrangement."

All ocean basins experienced significant warming since 1998, with the greatest warming in the southern oceans, the tropical/subtropical Pacific Ocean and the tropical/subtropical Atlantic Ocean. As the paper puts it:

"The Atlantic Ocean and the southern oceans are the major new heat reservoirs (59%) even though their total area is just 48% that of the global ocean."

Overall, about 32 percent of the extra heat absorbed by the ocean between 1960 and 2005 found its way to the deep ocean. Over the past decade, however, this proportion jumped to 49 percent, indicating that the deep ocean is playing an increasingly important role in ocean warming.

Mystery Explained

Finally, the authors combined their estimate of heat taken up by the oceans between 0-2,000m with a previous estimate of warming below 2,000m.

They found a good match with how much heat they would expect to find in the oceans as a whole, based on the amount of solar radiation entering and leaving the atmosphere since 1985. (Compare the yellow line in the graph below with all of the different shades of blue combined).

This means the mystery of the "missing heat" posed by Trenberth a while back is now effectively solved, suggested Palmer.

Proportion of the top of atmosphere (TOA) radiative imbalance expected to enter the ocean (yellow) with estimates of the ocean heat content at different depth levels (blue shading). Cheng et al., (2017)

A Travesty

Despite the fact that ARGO floats are largely to thank for having such detailed information about the oceans, the scientists behind the study fear for the future of the network. Abraham told Carbon Brief:

"I am not confident that we will have continued coverage. The current system uses state-of-the-art sensors that are spread out across the oceans … It is not clear that there will be continued funding for this absolutely crucial system in the current political climate in the U.S."

The Oceanic and Atmospheric Research program at the National Oceanic and Atmospheric Administration (NOAA) is in line for a 26 percent cut and ocean observation and ARGO come out of that budget, Trenbeth told Carbon Brief. What's more, many other countries provide their contributions as a percentage of the NOAA contribution, he added:

"If NOAA cuts back so do others—and it all goes downhill … Argo is still a research enterprise, not an operational one. It is vulnerable. Such a cutback would be a travesty."

Reposted with permission from our media associate Carbon Brief.

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By Robert McSweeney

The oceans are a hugely important "carbon sink," helping absorb CO2 emissions from human activities. Without them, CO2 would accumulate more quickly in the atmosphere, raising temperatures more quickly.

A new study, published in Nature, finds that recent changes in circulation patterns in the world's oceans are playing a key role in how much CO2 they take up.

Weakening circulation patterns have boosted how much CO2 the oceans absorb since the 2000s, the researchers said, but there's no guarantee that this will continue into the future.

Circulation Patterns

The Earth's oceans have absorbed about a third of the CO2 that humans have emitted into the atmosphere since the beginning of the Industrial Revolution.

But the amount of CO2 that the oceans absorb isn't constant. In the 1990s, ocean CO2 uptake dropped off, before increasing again in the 2000s. Recent research shows that the Southern Ocean was central to these changes.

The Southern Ocean is the most prolific of the oceans for carbon storage—accounting for approximately 40 percent of the global ocean CO2 uptake. In the 1990s, strengthening winds circulating around Antarctica affected ocean currents and brought carbon-rich water to the surface. This meant the ocean was less able to absorb CO2 from the atmosphere.

In the 2000s, the winds continued to strengthen, yet the CO2 uptake in the Southern Ocean rebounded. This, combined with increasing CO2 uptake in other oceans, suggested to scientists that there was, ultimately, another factor affecting the ocean carbon sink.

The new study says the reason lies in circulation patterns in the top 1,000m of the world's oceans.

Missing Piece of the Puzzle

The water in our oceans is constantly on the move. In the upper layers of the ocean there are several driving forces responsible, explains lead author Dr. Tim DeVries, an assistant professor in oceanography at the University of California. He tells Carbon Brief:

"The [circulation patterns] are driven by winds and by 'buoyancy forcing'—which means changes in the density of surface waters due to changes in their temperature (heating/cooling) or salinity (adding/removing freshwater)."

Using observed data, the researchers built a computer model to simulate these circulation patterns in the upper ocean. They ran their model to analyze the exchange of CO2 between the ocean and atmosphere over recent decades.

They found that in the 1990s, the ocean circulation patterns were "more vigorous" and coincided with a big dip in CO2 uptake. From around 2000, the circulation patterns then weakened, bringing a rebound in CO2 uptake.

The simplified diagram below illustrates the effect these "overturning" circulation patterns have.

Stronger ocean overturning—as seen during the 1990s—brings more carbon-rich water up from the deeper ocean, the researchers said. When this water reaches the surface it releases CO2 into the atmosphere (see a). More vigorous overturning also means the ocean takes up more CO2 from the atmosphere (b), but not as much as the extra CO2 released.

As the bottom half of the diagram shows, weaker overturning in the 2000s reduces both the amount of CO2 released to the atmosphere (c) and what is absorbed again (d). Overall, this increases how much CO2 the ocean takes up.

Simplified conceptual diagram illustrating how changes in upper-ocean overturning circulation have affected the ocean CO2 sink. Figure shows the a) increased release and b) increased uptake of CO2 during the 1990s—with an overall reduced CO2 sink, and the opposite in the 2000s (c and d). DeVries et al.

The results show that fluctuations in upper ocean circulations are "absolutely the driving force in the variability of ocean CO2 uptake," said DeVries.

In an accompanying "News & Views" article, Dr. Sara Mikaloff-Fletcher, from the National Institute of Water and Atmospheric Research in New Zealand, agrees. She wrote:

"[The paper] is the first to robustly quantify the role of circulation change in the recent decadal shift in CO2 uptake, providing the missing piece of this puzzle."

Major Advance

The paper is a "major advance" in the understanding of changes in the ocean carbon sink, said Mikaloff-Fletcher, but it isn't able to give us any clues for the future:

"It remains unclear for how long the increased carbon uptake observed during the 2000s will persist."

In general, scientists expect that as CO2 levels increase in the atmosphere, more will dissolve into the ocean. DeVries explained:

"The rate at which CO2 is transferred from the air into seawater depends on the difference in the concentration of CO2 in the air and that in the water. So, as humans put more CO2 in the atmosphere, this concentration difference increases and the ocean absorbs more CO2."

If the weak circulation patterns continue, this "may help to enhance the oceanic CO2 sink for some time," the paper says. But there is also the distinct possibility that the changes we are seeing now are temporary, said DeVries:

"The overturning circulation [could] switch back to a more vigorous state in the next decade. In this case, the changes would be reversed and we would go back to a weaker ocean CO2 sink (like in the 1990s)."

This would lead to a faster accumulation of carbon emissions in the atmosphere—and more rapidly-increasing temperatures.

Human-Caused Warming

The researchers don't yet know whether the recent weakening of the ocean circulation patterns are caused by natural variability or human-caused warming.

Global warming is expected to have a similar weakening effect on the circulation patterns as has been seen since the 2000s, DeVries said:

"Human CO2 emissions cause warming … of the surface ocean and makes it less dense. At the same time, the warming melts glaciers and ice caps, which pour fresh water into the ocean. This also makes the surface waters less dense. As surface waters get lighter, they are less likely to sink. This weakens the overturning circulation."

However, at the moment, it's likely that natural variability in the oceans is the dominant factor, said Prof. Nicolas Gruber, professor of environmental physics at ETH Zürich, who wasn't involved in the study. He tells Carbon Brief:

"My working hypothesis is that it is natural variability, but only time will tell. I say this because model simulations suggest that the point where the human-caused impact on the ocean carbon sink is clearly separable from natural variability is rather distant in the future."

Robert McSweeney covers climate science. He holds an MEng in mechanical engineering from the University of Warwick and an MSc in climate change from the University of East Anglia. He previously spent eight years working on climate change projects at the consultancy firm Atkins. Reposted with permission from our media associate Carbon Brief.

By Leo Hickman

The National Aeronautics and Space Administration (NASA), the U.S. space agency, has released an "eye-popping" three-dimensional animation showing carbon dioxide emissions moving through the Earth's atmosphere over the course of a year.

It says the 3-D visualization is "one of the most realistic views yet" of the "complex patterns in which carbon dioxide in the atmosphere increases, decreases and moves around the globe."

The data used to produce the visualization was collected by NASA's Orbiting Carbon Observatory-2 (OCO-2) satellite from September 2014 to September 2015. The data was then modeled and visualized by the Global Modeling and Assimilation Office at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Carbon Brief emailed some questions to NASA about the visualization, which it says is the first of its kind. The answers below are provided by Dr. Lesley E. Ott, a carbon cycle scientist at Goddard's Global Modeling and Assimilation Office and Gregory W. Shirah, who leads the development of Earth science-related scientific visualizations at Goddard.

Carbon Brief: How was the visualization "made"?

Dr. Lesley E. Ott: The carbon dioxide field was produced by combining information from our GEOS modeling system with OCO-2 observations using a technique called data assimilation. In this merged view, the model helps fill in gaps where OCO-2 can't observe and also provides more information about the 3D structure of atmospheric carbon dioxide, which is quite complex but can't be observed directly from the satellite. Meanwhile, the data helps correct errors in the model's emissions and transport patterns. This carbon dioxide analysis provides one of the most complete, data-driven views of atmospheric carbon dioxide to date.

Gregory W. Shirah: To make the actual visualization (ie, paint the pixels), we use Pixar's Renderman to render the images. We use Autodesk's Maya to set up the 3D environment and we used IDL to process the data. My colleague and I actually just gave a talk at Pixar today and showed this movie to them.

Carbon Brief: Specifically, what questions are you hoping it will help to answer?

Dr. Lesley E. Ott: The main goal of OCO-2 and most carbon cycle modeling is to better understand the processes that control carbon sources and sinks. About 50 percent of human emissions are absorbed by plants on land and in the oceans, but scientists don't have a good understanding of how or even where this is happening. We start by running the model with a 'first guess' of sources and sinks, and the data assimilation allows us to quantify how and where the model differs from the observations. Eventually, we'll be able to use these techniques to create more accurate maps of source and sinks, and from there we can improve climate models to better predict changes in the natural carbon cycle. This analysis product is something of a mid-point. We still have a lot of work left to do to understand the carbon cycle more fully, but developing these modeling and data assimilation tools is an important advance that will help us get where we need to be.

Carbon Brief: Why are these questions so important to answer?

Dr. Lesley E. Ott: Understanding the natural land and ocean carbon sinks is critical to understanding and predicting the trajectory of climate over the coming decades. If the land and ocean can't continue to sequester carbon at the current rate, we could see carbon dioxide accumulate in the atmosphere more quickly than we're expecting, leading to more rapid climate change.

Carbon Brief: The CO2 seems to be largely concentrated in the Northern hemisphere. Beyond this being where the majority of human-caused emissions are released, please can you explain the processes driving this and what the implications might be?

Dr. Lesley E. Ott: The highest carbon dioxide mixing ratios are seen in the Northern hemisphere during winter months. Most of the human emissions originate from this region, but it also holds the majority of the world's land masses and vegetation stocks, which decompose and release carbon during the winter. When plants start to grow again in the spring, you see massive amounts of carbon drawn out of the atmosphere, but not quite enough to balance out the increase from human emissions. If we ran the visualization for a longer time period, you would see the carbon dioxide released in the north mix with southern hemisphere air, but that inter-hemispheric mixing can take about a year. So even though that mixing is going on here, what really jumps out is the seasonal cycle of carbon dioxide.

Carbon Brief: How is this new visualization an advance on ones produced before?

Dr. Lesley E. Ott: Before OCO-2, we had a satellite called AIRS [Atmospheric Infrared Sounder] providing information about CO2. There's an example of what that data looks like here.

AIRS was designed to study temperature and moisture, primarily, but did give information about carbon dioxide in the mid- and upper troposphere. Since it has very little information near the surface to tell us about sources and sinks, it hasn't been as widely used as the datasets from GOSAT and OCO-2.

Looking at the OCO-2 data alone is also interesting—take a look at this.

and this.

The first animation shows the observations with minimal averaging at first and then switches to a view of the data averaged over larger areas to fill in the map. This is nice for giving a sense of what OCO-2 can and can't do. It's a huge advance over AIRS, both in terms of near surface sensitivity and accuracy. At 0.25 percent (or 1 parts per million, ppm), OCO-2 gives us one of the most accurate atmospheric composition measurements ever made from space. But the trade-off is that we can't make OCO-2 observations in cloudy regions or areas with high aerosol loadings. And because the measurement technique uses reflected sunlight, there are no measurements during night or polar night. OCO-2 also has a fairly narrow swath as you see early in the first video meaning that we can only observe a subset of the world every day, even under ideal conditions. When we try to average the measurements to cover some of these gaps, you can see that we get a sense of where CO2 is being taken up and released, but we still have large gaps in coverage in high-latitude regions and that sense of how CO2 moves through the atmosphere really isn't there.

As highlighted in the new animations, the alternative method of creating CO2 maps from observations through assimilation into a weather model (compared to the OCO-2 averaging shown above), preserves much more detail about the atmospheric transport. The model brings in information in areas without observations, but it also brings all the vertical information since the OCO-2 measurement is column only. This animation is also new and produced from the same dataset.

That really shows you how the data assimilation technique is working. Early on as the movie is going fairly slowly, there are some nice examples of how the model is helping us interpret what the observations are capturing. In the observations, we can see transitions between high and low CO2, but the merged product underlay helps us understand that those are due to the movement of weather fronts or plumes of fire emissions off of Africa. We chose to highlight the 3D visualization which is flashier, but this one is also quite informative.

Gregory W. Shirah: We have created some 3D (volumetric) visualizations in the past—I think of CO2 from AIRS—but they were very limited. For example, relatively small/regional areas, like Southern California or single snapshots in time from a swath of satellite data. To my knowledge, this is the first time a global, time-varying CO2 model has been shown this way. I'm not even sure if any global model has been shown this way.

Reposted with permission from our media associate Carbon Brief.

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In what's widely being described as the most shocking upset in U.S. election history, Donald J. Trump has beaten Hillary Clinton to become the 45th president of the U.S.

As one of the world's largest greenhouse gas emitters, any change at the top of U.S. politics warrants a consideration of what it might mean for the country's climate and energy priorities.

But given Trump's comments on the campaign trail, the U.S.'s recent reputation under Barack Obama as a nation serious about tackling climate change now looks to be in peril.

For example, Trump said he thought climate change was a "hoax" perpetrated by the Chinese. In addition, he pledged to end federal spending on low-carbon energy and to pull the U.S. out of the UN's Paris agreement on climate change. Carbon Brief has been asking climate scientists for their reactions.

Dr. Philip B Duffy, executive director of the Woods Hole Research Center and former senior policy analyst in the White House Office of Science and Technology Policy:

Dr. Malte Meinhausen, senior researcher in climate impacts at the University of Melbourne and the Potsdam Institute for Climate Impact Research:

"Trump said a lot of things. It looks like the Trump administration could do anything. From playing a destructive role in international climate protection to just letting others get on with the job … However, despite the momentum for climate protection having, in part, an autonomous motor due to the economics of lower cost renewable energies, a hostile Trump administration towards the Paris agreement could do a lot of damage.

"Trump won't be able to withdraw from the Paris agreement for three years (Article 28) now that it just entered into force—one of the world's major success stories. A hostile Trump administration could, however, withdraw from the UNFCCC Convention and thereby also from the Paris agreement indirectly. In theory, that could happen quicker. It's unlikely that the administration would do so much self-harm, so. But Trump seems to defy conventional wisdom, so we don't know.

"The Paris agreement without the U.S. would live on, but the spirit and the international focus on one of the defining challenges of our time could get lost. And the economic opportunities for the U.S. will get lost too … Not a good outcome for the U.S. in that respect. Not a good outcome for the climate. Too early to tell how bad it will be, though. One can hear the world gasping for air."

Prof. Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research:

"President-elect Donald Trump's stance on global warming is well known. Ironically, he contributed to the popularity of our recent Turn Down the Heat report series for the World Bank by attacking it on Twitter.

"Yet apart from this, science cannot expect any positive climate action from him. The world has now to move forward without the U.S. on the road towards climate-risk mitigation and clean-technology innovation.

"The U.S. de-elected expertise and will likely show a blockade mentality now, so Europe and Asia have to pioneer and save the world. Formally leaving the Paris agreement would take longer than one Presidential term, yet of course the U.S. could simply refuse reducing national emissions which would mean a de facto exit out of international climate policy. Now the U.S. are one of the world's biggest economies and even just four years of unbridled emission staying in the atmosphere for many hundreds years would make a substantial difference. The climate system doesn't forget and it doesn't forgive. The U.S. is prone to potentially devastating climate change impacts. Hurricanes hit U.S. coastal cities, the California drought affected farmers and a state like Florida is particularly exposed to sea-level rise. Sadly, in the long run nature itself might show the U.S. citizens that climate change as a matter of fact is not a hoax. But it might be too late."

Dr. Rachel James, research fellow in climate modeling at the Environmental Change Institute at the University of Oxford:

Dr. Twila Moon, lecturer in cryospheric sciences at the University of Bristol:

"Having a person in the position of U.S. President who does not acknowledge scientific facts establishing the clear reality of human-caused climate change is a disgrace. This is a sad and scary outcome for science and for action on halting harmful climate change.

"But I am hopeful that the American people—from all parties—are realizing that climate change is happening in our own backyards and the will of the people will push the political needle. I think our response must be to work harder, together to move forward on climate action locally, regionally, and, as best as possible, nationally. As a human being, I think it is our moral obligation."

Prof. Andrew Dessler, professor of atmospheric sciences at Texas A&M University:

"I don't think anyone knows what this means for U.S. policy on climate science or emissions reductions. I think we all expected that the Clean Power Plan would end eventually up in front of the Supreme Court and its fate there is more doubtful now that Trump gets to appoint the next Justice. On the other hand, renewable power is getting cheap fast and my optimistic hope is that renewable energy gets so cheap that we switch to it without any national government policy. I guess we'll see!"

Prof. Shaun Marcott, professor in palaeoclimate at the University of Wisconsin-Madison:

"This election in terms of future global climate change was critical as the new president will be making decisions that will have long lasting consequences, both in the policy being set in the homeland and policies that they will help set with their international counterparts.

"Much like Britain and the Brexit vote, the U.S. now finds itself at a crossroad and heading in a direction that, in my opinion, does not appear to be sustainable. This is obvious, I think, to most people. I think the best way I've heard it described is that decisions made by this incoming president will set in policies that could have lasting climate change effects extending 10,000 years into the future. The stakes were high and unfortunately both of our leading candidates didn't even discuss, or did so very rarely, climate change at large in any of the debates."

Charles F Kennel, distinguished professor emeritus at the Scripps Institute of Oceanography:

Dr. Emily Shuckburgh, head of open oceans at the British Antarctic Survey:

"A significant theme of recent political discourse has been the use and misuse of evidence. In moving forward, rather than bemoan a 'post-truth world,' those of us who have roles in gathering, curating and disseminating evidence must strive to understand the process of human decision-making better.

"We absolutely need to make policy on climate and other matters that is consistent with the evidence base. But within a democracy, this has to be achieved through the will of the people. That requires broad and deep engagement by us with all sections of the wider society to understand the contextual circumstances and to proactively place the evidence in frames that are relevant to people.

"If we are to meet the objectives of the Paris agreement, it is abundantly clear that a major transformation of society will be required. This is a significant technological challenge, but the political events in the U.S. and UK that have surprised the establishment also serve to remind us the importance of recognizing the implications of change for all sectors of society. If we can learn from this, there is hope that we may be able to successfully navigate the perilous journey ahead of us in responding to the climate challenge."

Prof. Jean-Pierre Gattuso, professor of biological oceanography at the Centre National de la Recherche Scientifique, Sorbonne University and the Institute for Sustainable Development and International Relations.

"The result of the U.S. presidential election is very worrisome on many counts, including of course for climate negotiations. The Paris agreement is a construct that was many years in the making and is, therefore, extremely fragile. Even though the U.S. cannot formally leave the agreement in the next 4 years, not having the U.S. on board and pushing for the full implementation of the Paris agreement may well affect billions of people for hundreds of years. The outcome of this election is clearly not the end of the world but the consequences for humanity are potentially dreadful."

Prof. Jason Box, professor in glaciology at the Geologic Survey of Denmark and Greenland:

"Those of us in the sciences are all about the rational and we surround ourselves by rational media. The U.S. election outcome reflects the irrational and how those voters were influenced by irrational media."

Dr. Michael. E. Mann, distinguished professor of atmospheric science at Penn State University

"To quote James Hansen, I fear this may be game over for the climate."

Prof. Eric Steig, professor of earth and space science at the University of Washington:

"It's impossible to know just how far Trump and the Republican controlled House and Senate will want to push an anti-intellectual, anti-science agenda. I suspect there will be more immediate political concerns. In the medium term, I don't expect there will be major cuts to science funding; I think Trump will likely govern less as an ideologue and more as an opportunist in this respect. It now is exceedingly unlikely, of course, that any international climate change mitigation agreements will proceed; or if they do, it will not be with the U.S on board."

Dr. Niklas Höhne, professor for mitigation of greenhouse gases at Wageningen University and founding partner of the NewClimate Institute:

"This election result seriously threaten the U.S.'s federal climate action. In the worst case, Trump will work towards reversal of the Clean Power Plan. If the Clean Power Plan was to be permanently stopped, emissions projections would be significantly higher than in its absence and we would be seeing an increasing emissions trend over the next decade—at around 6 percent below 2005 levels in 2025. All eyes are now on the federal states to pursue further climate policies, but the impact on the USA's overall contribution may be limited. This means that the climate target that the USA communicated as part of the Paris agreement process, the 'nationally determined contribution,' will probably not be met and U.S. emissions will remain stable at current levels until 2030.

"In spite of this grave eventuality of no climate action from the new U.S. federal government on the horizon, there is still hope that global greenhouse gas emissions can be reduced. Technological developments can be triggered by transformative coalitions, smaller groups of countries that actively support a technology, to eventually achieve global scale. We have seen this model work for renewable energy. The renewable energy agenda was initially supported by a few pro-active countries such as Germany, which brought the costs down to the extent that renewable technologies are now the 'new normal' for new power plants in many places in the world. Similar developments can be seen with electric mobility where Norway, California and, in particular, China are aggressively supporting electric cars. It is fair to believe that these would also become the 'new normal' in a few years time."

Prof. Jim Skea, professor of sustainable energy at Imperial College London and co-chair of IPCC Working Group 3:

"IPCC is a scientific body with 195 countries making up its membership so I don't expect it to make any pronouncement on political developments. But as a scientist involved in IPCC, I can say that U.S. scientists have made a huge contribution to climate science in general and IPCC in particular across all the assessment reports. This is something that the U.S. can be very proud of. It's far too early to tell how the next administration will approach these issues. In my experience there has been a remarkable consistency in the U.S. approach to IPCC across different administrations. And, again, with much practical climate action in the U.S. taking place at the city and state level, it's too early to say how things will pan out in the policy domain."

Prof. Katharine Hayhoe, atmospheric scientist and associate professor of political science at Texas Tech University:

"The bright light of hope the Paris agreement shone on the bleak and discouraging landscape of climate change has been dimmed but not extinguished."

Reposted with permission from our media associate Carbon Brief.

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.

Sponsored

By Sophie Yeo

How do you reduce CO2 emissions? The Global CO2 Initiative is pushing a unique approach: turn them into useful products, then sell them.

Based in San Francisco, the company has the ambitious aim to capture 10 percent of global CO2 emissions through carbon capture and usage. While this method is still in its infancy, the initiative aims to commercialize new ideas quickly by granting up to $100 million a year for 10 years to researchers developing viable new products. Its global advisory board includes Steven Chu, the former U.S. Secretary of Energy, and Jeremy Oppenheim, program chair of the New Climate Economy project.

Carbon Brief spoke to Dr. Issam Dairanieh, the company's CEO, about his idea to tackle climate change through CO2 reuse. He explained what carbon capture and usage is, and how it could play a role in future efforts to reduce emissions:

"The idea here is go with what we call 'carbon negative technologies.' So think of trees on steroids. That's really what it is. So it is acceleration absorption of CO2 converted into products. Nature does it, does it very well, but does it slowly, and our solution says let's see what nature does, and do that extremely fast. So, instead of years, we want to do that in minutes. And the idea here is really all about developing and commercializing technologies that can absorb CO2 and convert it into useful products."

He spoke about the products that can be made using CO2 and their potential reduce emissions:

"The first product that we are going to invest in is making cement. So think about cement and concrete and how much is produced. It is probably the material that has the highest amount of any material that man makes, basically. Just this product contributes over 7 percent of the global emissions of CO2. We have identified a company that produces cement and concrete at a carbon footprint 70 percent less than what's currently done. So imagine what we can do with this. If you can replace everything we're doing right now with this new type of cement material, you will reduce global emissions by 5 percent, which is significant. What we have set out to do is, we said we want to reduce carbon emissions by 10 percent a year. That's really our objective. And we think that just by adopting one technology we will be able to reduce it by half of our target."

He talked about how best to capture CO2 emissions to be used in products:

"Where we're going to start is where it's very easy to do so. So, if you go to power plants, CO2 is mixed with other things. The concentration can be anywhere between 3 percent and 12 percent, maybe 13 percent, but that's about it. However, if you go to different places, in a refinery where hydrogen is generated using something called methane reforming, when you do that, you generate pure CO2 that's just emitted. We think there is 100, 200 million tons of that that we can go to. The second area is if you look at how biofuels are made, when you ferment basically biomass and you end up with ethanol that's used in biofuels. As a byproduct, you get a stream which is 100 percent CO2, so you don't have to concentrate, you don't have to purify—it's there."

Reposted with permission from our media associate Carbon Brief.

By Simon Evans

Saturday, April 9 was the first-ever day where more electricity was generated in the UK by solar than by coal. May 2016 was the first-ever month. The three months from June through to September was the first-ever quarter. And now the six months to September is the first half year.

The UK's pioneering community energy project, Westmill Solar Park and Wind Farm in Oxfordshire, England.Richard Peat via Flickr (CC BY-NC-ND)

These firsts reflect the changing face of UK electricity supplies, with solar capacity having nearly doubled during 2015. They also reflect historic lows for coal-fired generation, driven by changes in wholesale energy markets and the carbon price floor. Carbon Brief runs through the numbers.

Solar Six Months

The UK's solar panels generated an estimated 6,964 gigawatt hours (GWh) of electricity during quarter two (Q2) and three (Q3) of 2016, from April through to September. (See note below regarding data sources and methodology).

The solar output was equivalent to 5.2 percent of UK electricity demand for the half-year period. It was nearly 10 percent higher than the 6,342 GWh generated by coal, which covered 4.7 percent of demand.

Shares of total UK monthly electricity generation met by solar and coal during 2016 (%). Sources: Sheffield Solar and Gridwatch. Chart by Carbon Brief using Highcharts.

Starting on July 1, there were 10 straight weeks when solar output exceeded that from coal.

Solar output is strongly affected by the UK's seasonal cycle. Roughly three-quarters of annual UK solar power is generated during the sunnier half-year from April to September. In contrast, coal generation tends to increase in winter when electricity demand peaks.

The chart below shows these contrasting seasonal cycles. It also shows two contrasting broader trends.

First, UK solar capacity has to date reached around 12 gigawatts (GW), according to research by Solar Intelligence, up from around 6GW at the start of 2015. Solar generation is increasing as a result, up 26 percent in 2016 to date, compared to the same period in 2015.

(Note that solar capacity additions have fallen this year, following subsidy cuts. Note also that while government figures for new capacity have been consistently too low, independent estimates also show the drop.)

Total electricity generation from UK solar and coal during calendar months in 2015 and 2016 to date, gigawatt hours (GWh). Sources: Sheffield Solar and Gridwatch. Chart by Carbon Brief using Highcharts.

Second, the chart shows how coal generation has fallen rapidly, at a rate that is far beyond its usual annual cycle. Output in 2016 to date was 65 percent below that in 2015. It was down 76 percent in Q2 and 82 percent in Q3 compared to a year earlier.

This year also saw UK coal generation fall to zero on April 9, for the first time since 1882, when a coal-fired power station started supplying electricity to the public for the first time. Since then, there have been 199 hours when coal was generating no power in the UK.

The drop in coal output has come about because of wholesale energy market price shifts being more favorable to gas-fired generators than to coal. In addition, the UK's carbon floor price doubled in April 2015, again shifting the economics of electricity generation in favor of gas over coal.

Given these price changes, and the government's stated intention to phase out all unabated coal by 2025, three coal-fired power stations took the decision to close this spring.

The key role of the carbon floor price in driving coal off the system is underlined in recent analysis from consultancy Cornwall Energy. This shows that removing the UK's top-up carbon tax would mean coal plants once again being cheaper to run than gas.

Tom Edwards, Cornwall Energy senior consultant writes:

"This would return the market to the position seen in 2014 when coal-fired generators were running baseload [all the time] and gas-fired stations were pushed to the margin."

It's worth noting that while gas-fired power stations have replaced most of the reduction in coal output, the total supplied by the two fossil fuels is also falling. This is because of increases in electricity supplied by renewables and imports, along with falling demand.

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Methods: The figures for shares of total UK electricity generation are estimates. They only include solar generation and other forms of generation that are connected to the transmission grid network. Embedded generation from wind or other sources is not centrally metered and data is not available. However, this missing data will not alter the relative positions of solar and coal generation.

Figures for solar output in the UK are estimates produced by Sheffield Solar. The project recently updated its estimates of installed UK solar capacity. Its estimates scale real live data obtained from 324 solar sites around the UK.

Carbon Brief analysis shows the Sheffield Solar estimates to have a very small average error of 4%, compared to official government figures for solar generation since the start of 2015.

Reposted with permission from our media associate Carbon Brief.

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