Hurricane Sandy floods a street in Lindenhurst, Long Island. Jason DeCrow/CC BY SA/2.5

Half the Global Population Could Face 'Unknown' Climates by Mid-Century

By Robert McSweeney

Billions of people across the world could see climates they've never experienced before by the middle of the century, a new study said.

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Bonn Climate Change Conference. UN Climate Change / Flickr

U.S. Tells China It Has 'No Plan Yet' to Meet Its 2020 Climate Target

By Simon Evans

The U.S. has no plan yet for how to meet its 2020 climate target and has made no analysis of the impact of recent policy changes, according to an official submission to the UN.

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The 1981 TV Documentary That Warned About Global Warming

By Leo Hickman

On the evening of Tuesday, Dec. 8, 1981, the UK's only commercial TV channel, ITV, broadcast an hour-long documentary, Warming Warning.

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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.

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Photo credit: iStock

Rate of Ocean Warming Quadrupled Since Late 20th Century, Study Reveals

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.

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Scientists Solve Ocean 'Carbon Sink' Puzzle

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.


NASA Produces First 3D Animation of Global Carbon Emissions

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.

16 Climate Scientists React to Donald Trump’s Victory

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.


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