Sunlight: the equitable energy source

Solar energy is touted for a variety of reasons – it’s renewable, clean, quiet, and can be used as a decentralized form of electricity generation.  But I came across a figure while doing some reading that reveals a less-discussed benefit of using solar energy that may be most important (depending on your priorities when it comes to global issues).

Below is the figure, reproduced from a recent 2015 paper in Energy and Environmental Science that reviewed all that we know about the solar resource and the technology we’ve created to harness it.  I’ll show it first and then discuss its important details.


There’s a lot going on here, so let’s break it down.  The top left image (a) shows the irradiance, or power per square meter (W/m2), as a function of geography.  This tells us just how much solar energy is hitting the surface over a given time and area.  As would be expected, the most solar power arrives closer to the Equator, with the largest amounts of available power located in the US Southwest, Sahara, central Asia, and Australia.

However, the intriguing benefits of solar energy are revealed when we look at averaging this available power across longitudes or latitudes.  Figures (b), (c), and (d) plot land area, population, and irradiance as a function of longitude, averaged across latitude.  Notice how solar power is consistently available across all longitudes (Figure (d))!  To a certain limit, it doesn’t matter where you live in the Eastern or Western hemisphere – solar power will be available to you.

Figures (e), (f), and (g) similarly plot land, population, and available solar power as a function of latitude, averaged across longitudes.  Here, we see a slightly different but still beneficial pattern.  Clearly, less solar power is available near the Arctic and Antarctic poles (Figure (g)), but the level of irradiance still generally correlates with the largest population densities, particularly near the 30 degrees N latitude line (compare (f) and (g)).

So, on average, people across the globe live close to available solar power.  That’s a good start, but there’s more!  Figure (h) plots the GDP per capita of countries in 2011 against the amount of the solar energy hitting that country per square meter per day (known as insolation).  This type of scatter plot is a great tool for visualizing correlations between two variables.  If GDP per capita and insolation were positively correlated, for example, then we would see richer countries have much higher levels of insolation than poorer countries.  Fortunately, that’s not the case!  Instead, almost no correlation exists between these two variables, indicating that all countries have a similar potential to harness solar energy to power their homes, businesses, and communities.

Consider the implications.  Across geography and wealth, no country lacks direct access to sunlight as an energy source.  The same cannot be said of coal, oil, or natural gas, all of which require extraction of resources from geographically specific locations.  Developing countries with less GDP per capita even have a slightly larger solar resource, on average, indicating the potential to use capital investment and infrastructure in the solar industry to spur growth in these countries.

Of course, developing countries can do little with the available solar energy if their governments or policies are not equipped to take advantage.  But no extractive energy resource boasts these benefits of geographic and economic equality.  Just another reason to support the advancement of solar technology and economic development plans that encourage its distribution!


Figure courtesy of Jean J et al. “Pathways for photovoltaics.” Energy Environ Sci8, 1200, 2015.

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The Presidential Promise of a Half-Billion Solar Cells

Figure courtesy of Walmart via Flickr

Figure courtesy of Walmart via Flickr

It is my pleasure to introduce Adam Kirk as guest writer for this week’s post!  Adam is a freelance writer specializing in renewable energy and associated topics.  To find out more or hire Adam for your own website, visit

Last week, Hillary Clinton secured the nomination of the Democratic party for this year’s presidential election.  The stark contrast between the environmental positions of the Democratic and Republican platforms are being highlighted more so than other recent presidential campaigns.  With the election coming so soon after the Paris Agreement on climate change and off the back of Obama’s own Clean Power Plan, there is voter value in the pledges made by candidates with respect to the environment.

Large  divisions between Donald Trump’s and Hillary Clinton’s views on global warming provide a sharp contrast for voters making decisions based on environmental concerns. Trump has been quoted in the past year stating that “green energy is just an expensive feel-good for tree-huggers” and that “I’m not a big believer in man-made climate change.” These statements would seem to echo the view of many in his party, including most of the original presidential candidate contenders.

On the other side, Hillary Clinton has been very vocal in her belief that more effective action needs to be taken by the US, declaring that “we do not have to choose between a healthy environment and a healthy economy”, but not before handling potential challenges from her past role in the Obama administration.  Indeed, she clearly admits to the United States’ role in global warming, stating that “we acknowledge – now with President Obama – that we have made mistakes in the United States, and we along with other developed countries have contributed most significantly to the problem we face with climate change”.

Based on these positions, the ‘pro-environment’ candidate is Hillary Clinton. What, exactly, is she planning to do to deliver on the rhetoric? The answer, as you will see shortly, is certainly ambitious.  The question is: can she deliver?

Hillary Clinton: Leading on Environmental Change?

Hillary Clinton and the Democrats sit firmly on the side wanting to fight climate change. As evidence, she has laid out a challenging plan and committed to implement it on ‘day one’.  In July 2015, Hillary Clinton and her campaign team set out her commitments on the environment in this briefing document. In essence, it contains two key commitments:

  1. By 2020 (i.e. the end of her first term as president) the USA will have half a billion solar panels installed.
  2. Within 10 years of her taking office (2027) the USA will generate enough clean, renewable energy to power every home in America.

Let’s examine each of these goals and understand how she plans to achieve such an ambitious proposal.

1) A Half-Billion Solar Panels by 2020

500,000,000 solar panels is a huge number and it helps to put some context around it.

The Topaz Solar Farm in southern California is the fourth largest PV power station in the world with 9 million solar panels generating 550MW.

Those nine million panels are just 1.8% of Hillary Clinton’s target; she’ll need to establish 55 Topaz’s to reach her 2020 goal.

Fortunately, she’s not starting from nothing.   The USA already has three of the largest five PV power stations in the world (China and India have the largest two) and over half the largest 20.  Talking about them in terms of solar panel count may be great for attracting votes, but it is not helpful when considering energy production.  For example, the USA’s largest PV power plant is Solar Star, also in southern California. It generates 579 MW to Topaz’s 550 MW, but only uses 1.9m panels to achieve it – less than a quarter of Topaz’s count.

This is an important distinction because it is the efficiency of the panels used which will be just as important as their number. The best efficiency today of commercially available PV cells is around 20%, but science lab’s have produced crystals with efficiencies as high as 44.4%. It’s easy to see that technology twice as efficient as today’s panels means less land, fewer materials, and lower cost to produce the same amount of energy.

With panel efficiency in mind, instead of using a panel count as a primary goal, the more useful detail under the half-billion pledge is the capacity target of 140 GW by the end of 2020 (although there’s no mention of the assumptions underpinning the link between a half billion panels and 140 GW, the math suggests if the calculation assumed the efficiency of Solar Star’s panels Clinton would need around 460 million of them to produce 140 GW).  At the end of 2015, America had 25 GW of PV power capability with 30 GW of additional capacity planned. There’s an additional 6 GW in distributed generation from residential and non-residential premises, summing to give 61 GW of power available/planned when Clinton takes office.

At 140 GW, the Clinton solar commitment would require doubling that capacity over the next four years, which might appear unfeasible. However,  recent growth in solar energy is booming. This chart shows growth solar-produced energy was sluggish in the US until 2011, before hitting ‘hockey stick’ exponential growth. Between 2013 and 2014, production levels doubled. Not only that, according to the US Department of Energy, the number of homes using solar energy increased 10-fold from 2006 to 2013, and is expected to increase another 2 – 10 times before Clinton’s 2020 deadline. It almost feels like a hard target to miss.

2) Enough Clean, Renewable Energy to Power Every Home in America

This eye-catching statement is another great one for voters but its wording could be misleading.  The target could be every home will be powered by clean energy, or the US will produce enough energy that the total energy use of American homes could be met by electricity produced from clean sources in 10 years.

Assuming the latter scenario of an equivalent production, the demands are startling. The amount of energy required to power the equivalent requirement of all the homes in America (125 million in 2015), consuming around 11,000kWh each, is almost 21,000 Trillion British Thermal Units. Just 770 Trillion of those, or 3.7%, were fueled by clean power technologies.

This second pledge seems significantly more challenging to achieve. It needs a 30-fold increase in last year’s production to achieve her 10-year goal and, perhaps more significantly, it increases the Clean Power Plan target of energy coming from renewables by 2027 from 25 to 33 percent.  

It is no surprise in the face of such an ambitious target that the language shifts away from talking solely about solar to ‘clean renewable energy’. Moving the focus makes sense pragmatically, given that wind electricity production in the US is already around three times that of solar.  It also make political sense, since voters in states like Iowa, where almost a third of their power came from wind last year, might feel snubbed with all efforts devoted only to the solar industry.  

According to Energy Information Administration projections, wind energy production capacity could double to around 180 GW in 2027.  Increasing clean energy production to provide 33% of the country’s needs is going to require both a variety of forms of energy production and lots of effective support.

If the goal is for every home to actually provide their own clean power, then wind, solar, geothermal, and biomass production will all need to be in the mix.

How Will the Plan be Achieved and What are the Challenges?

Hillary Clinton’s incentives revolve around a $60 billion mixture of competitions and ‘prizes’ to motivate states and communities to beat already-established targets, plus federal support to remove barriers for low-income families to install solar panels.

There are a number of obstacles she will have to face, not least of these being Republicans that are likely to retain power in the House of Representatives. If this occurs, her own campaign chair, John Podesta, recognises that Clinton’s hands will be tied when it comes to comprehensive energy policy change.  It seems her way of dealing with a Republican House is to work around it, which she appears happy to do.

The rest of her team appears to support the same tactic. In an interview with GreenTech Media earlier this year, Trevor Houser (Hillary Clinton’s energy policy advisor) explains she’ll work around Congress by using existing authorities, partnerships with states, and direct federal investments.

Aside from the Republicans, she has two other challenges to consider.  The first is the Keystone XL oil sands pipeline from Canada that is proposed to travel the length of the US. This project has become an anchor for a philosophical argument between the two sides of the environmental debate (how that happened is brilliantly explained in this New York Times video). The pipeline causes Clinton headaches for two reasons: the first is that she was Secretary of State when it was originally discussed – she has ‘skin in the game’ – and the second is that Obama is the person who has to authorise it coming over the border.  Being on his ‘side’, Clinton is constantly forced to decline sharing her view on whether she’d allow it or not so as not to undermine his position, possibly hurting her own environmental credentials.

Her second challenge of note is one which, depending on your perspective, could be characterised as being naive or dishonest.  There is significant opinion that Hillary’s plans for delivering the change she is pledging will only get us part of the way there and that the only mechanism that will really move the dial is putting a value (or tax) on carbon. Discussions of new taxes could be toxic for voters and a gift for Trump, so Clinton has made no mention of it to date, but perhaps she should take solace from this poll which suggests even a slight majority of republicans would be supportive of a carbon tax if it was managed in the right way (i.e., used for R&D in renewable energy or as a fee and dividend returned to the public).

What is Next for Hillary’s Plan?

Whatever your view, it is hard to argue that the objectives are not ambitious or for the good of the environment, although there are a lot of gaps still to be plugged.  

Clinton is pledging two significant environmental policy targets that will be set on her first day in office. The first goal of a half-billion solar panels is definitely lofty, but she would inherit 1) a momentum of growth in the industry , 2) a growing conviction that human-made climate change needs to be tackled proactively, and 3) technology that’s edging ever closer to higher efficiency (and so relatively cheaper) panels. In all, this feels very achievable.

The second target is substantially more ambitious. Hillary Clinton is setting out on a ten-year journey to increase the amount of sustainable energy produced in the US to 33% from today’s 3%. The incentive program to do this is large, but it faces substantial challenges from a Republican house and, as yet, no mention of what role taxes will play in achieving it. This is definitely the harder target to be positive about and, cynically, perhaps that’s why it’s only deliverable by a different president, even if Hillary achieves two terms in office.

As President Obama has discovered over the course of his eight-year journey, there is only so much even the West’s most powerful leader can achieve when political views are so polarised.  Even though she may have “put the biggest crack in that glass ceiling yet”, Hillary still has to wake up victorious on November 9th for her bold environmental plan to stand any chance at all.


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Carbon capture: transforming greenhouse gas into rock


This article was originally published by, which translates complex research findings into accessible insights on science, nature, and technology. Help keep GotScience free! Donate or visit our gift shop. For more science news subscribe to our weekly digest.

A few months ago, after drilling a well 400 meters deep, scientists in Iceland were repeatedly frustrated that the well kept breaking down. Retrieving the pump from the depths of the earth, they found its base covered in a scaly green and white material that clogged the end of the machine. Instead of feeling dismay over the equipment failure, the scientists celebrated. The crusty residue was calcite, a hopeful sign that the researchers had developed a new method to chemically trap carbon dioxide (CO2) underground and mitigate climate change.

A promise always a decade away

The idea of carbon capture and storage (CCS) has had many advocates and critics. The goal is simple: Find a way to grab all the CO2 emitted during fossil fuel combustion, and permanently sequester it somewhere on the planet, either in geologic formations or the deep ocean, where it cannot escape into the atmosphere. Supporters claim that the technology can create “clean coal,” allowing society to continue to burn away fossil fuels using existing infrastructure. Proponents have carried out a host of pilot projects, the most common using sandstone or depleted oil wells as storage sites, because engineers and scientists already know how these sites operate from the oil and gas business. Unfortunately, no feasible path to cheap and reliable CCS has come from this work.

The problem with current CCS technology is twofold. First, current state-of-the-art technology using old well sites is estimated to cost 50 to 100 dollars per ton of CO2 stored. Imagine that an initial goal of the technology would be to store just 20 percent of the 35.9 Gigatons of global CO2 emissions from 2014. This puts a minimum cost of such CCS at $359 trillion!

Price is not the only concern. Even if CO2 could be affordably stored in sandstone, the molecule’s probability of escape is too high. Rock layers typically cap these storage sites and are sensitive to seismic activity. Fissures in the rocks could allow fluid to leak through and provide the perfect vehicle for CO2 to escape back into the atmosphere. Researchers have not been able to find a storage site that prevents the possibility of this type of leak, making the long-term application of the technology infeasible.

The chemistry of carbon storage

Remember those happy Icelandic scientists? They just may have found a solution. Twenty-five miles east of Reykjavik, a team of scientists from Iceland, the United States, and Europe collected hot, bubbling CO2 from a nearby geothermal plant and injected it 500 meters underground to test a new carbon storage system. The destination: a basalt rock formation.

Why basalt?  Unlike sandstone formations, basalt, an igneous rock, contains many metals, such as calcium, magnesium, or iron, that facilitate a chemical reaction with CO2 known as carbonation. Carbonation transforms the greenhouse gas into calcite, a white and green rock. In contrast to sandstone, which physically constrains CO2underground in a densified gas phase, basalt chemically—and permanently—stores CO2. Fissures and water leaks could no longer allow the greenhouse gas to escape into the atmosphere.

The idea of basalt storage had been considered before, but most computer models suggested that calcite formation would take a decade or even hundreds of years. The scientists in Iceland wanted to try it anyway, at least to gain more information about the chemical process. After doping CO2 from the geothermal plant with heavy carbon to monitor its movement, the scientists plunged 220 tons of CO2 deep into the basalt formation along with a lot of extra water. The addition of water is crucial, because gaseous CO2 by itself could easily escape the injection site before reacting with the metals in the basalt. CO2 is not buoyant and dissolves in water, allowing the chemical reactions to complete before the CO2 degasses.

After the injection, all the scientists could do was watch and wait. Eighteen months after injection, the well broke down, and the elated scientists found the green and white, scaly calcite stuck to the bottom. The chemical reactions necessary for storage took only a little over a year, an order of magnitude less than that predicted by computer models. Over 95 percent of the injected carbon had been transformed into rock.

The speed of the carbonation “means this method could be a viable way to store CO2 underground—permanently and without risk of leakage,” says Juerg Matter, lead author of the study and geologist at the University of Southampton in the United Kingdom.

The difficult path to commercialization

The results from this experiment suggest basalt storage could solve the gas leakage problem intrinsic to most other CCS technologies. Once chemically bonded to form calcite, the CO2 is permanently stored as part of the rock formation. The findings are not specific to Iceland, either. Similar injections into basalt formations have succeeded in Wallula, Washington, and giant basalt formations in the Pacific Northwest make it a perfect location for upscaling the technology.

But challenges remain. More tests are required to confirm that carbonation of injected CO2 is consistently fast and that the Icelandic results were not an anomaly due to particular chemical conditions at the initial test sites. Speed could also be a drawback. If carbonation occurs too quickly, CO2 will not have time to spread throughout the entire basalt formation, limiting storage to locations near the injection site.

Even if these technological issues are addressed, price is still a concern. It is not clear whether basalt storage methods will reduce the price tag currently restraining the market growth of other sequestration technologies. As energy analyst Vaclav Smil has discussed, carbon capture technology requires a tremendous amount of infrastructure. Assuming we want to store just 20 percent of 2010 emissions, Smil estimates this would require transporting 8 billion cubic meters of compressed CO2 gas to storage sites. In comparison, the oil industry transported 4.7 billion cubic meters of crude oil in 2010. This means that carbon sequestration would require “an entirely new worldwide absorption-gathering-compression-transportation-storage industry” that is 70 percent larger than the global crude oil industry developed over multiple decades. Such a challenge would require global cooperation and infrastructure development at an unprecedented pace to prevent CO2from rising above 450 parts per million.

Any new CCS method must be viewed with a hopeful but critical eye. Basalt storage appears to be a technological leap that could lead to its adoption in certain cases, but including carbon sequestration as a major part of any climate mitigation plan will be limited more by politics and global infrastructure than by the viability of any one specific technology.


Matter J.M. et al. “Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions.” Science, 352(6291), 1312-1314, 2016.

Kintisch, E. “New solution to carbon pollution?Science, 352(6291), 1262-1263, 2016.

Smil, V. “Global energy: the latest infatuations.” American Scientist, 99, 212-219, 2011.

Photo Credits

Figure of Nesjavellir Geothermal Power Station courtesy of Gretar Ivarsson

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Australian rodent first mammalian victim of climate change


Tucked away on a small island off the coast of Queensland, Australia, the rat-like animal would have stared up at you with dark, beady eyes from the safety of some scattered shrubs.  No more than 15 centimeters long, the rodent would have been covered with light red fur, its tiny ears tucked tightly against its head, its pale underbelly barely visible.  You would have probably noticed the odd tail, as long as its body and lumpy with scales.

You may have seen this mosaic-tailed rat, melomys rubicola, had you traveled once upon a time to Bramble Cay, a small island built upon a the Great Barrier Reef.  But no longer.  After a fairly exhaustive search using traps, cameras, and searches on foot, Australian scientists have pronounced with confidence that the melomys is likely extinct [1].  The probable cause?  Evidence suggests dramatic weather conditions in the region combined with rising sea levels due to anthropogenic climate change  While a faint glimmer of hope remains that a small colony may still exist on poorly studied region of Papua Guinea, this is likely the first of many mammals to fall victim to the complex weather systems created by global warming.

The future, now

Why should we care?  Some will immediately sense the emotional connection: those cute little eyes and ears a victim of shameless human expansion across the globe.  And I don’t believe this sentiment can be overstated in these times, when we are moving farther and farther away from understanding our connection to the environment the effects of our industry on it.

But there is more to this loss than dealing with accomplice’s guilt.  The present weather systems bombarding Bramble Cay and their effects on the local ecosystem play out our future in fast-forward.  The island rests only 3 or 4 meters above sea level, leaving it susceptible to any slight changes in climate.  Whereas global sea levels have risen 20 centimeters over the last century, the oceans have risen at twice the average rate near Bramble Cay.  As a result, the area of the island consistently above high tide has shrunk since 1998 from 9.8 to 6.2 acres, eliminating the spread of vegetation, low-lying rock overhangs, and 97% of available habitat for the melomys.

As a group of scientists from the Department of Environment and Heritage Protection and the University of Queensland thoroughly documented the island, they found flattened, dead sedge along the coastlines, erosion, and the loss of soft substrate along rock formations.  All these signs point to dramatic weather systems recently hitting the cay.  In 2005, Tropical Cyclone Ingrid blasted the island, destroying up to half of all vegetation by 2011.  Harsh winters during the same time also brought more severe storms through the area.  Increased cyclonic activity near Queensland has already been associated with intensity in the La Nina cycle, which occurs with higher global mean sea surface temperatures due to anthropogenic global warming.  The melomys didn’t stand a chance given the loss of the vegetation and habitat.

“The key factor responsible for the extirpation of this population was almost certainly ocean inundation of the low-lying cay, very likely on multiple occasions, during the last decade, causing dramatic habitat loss and perhaps also direct mortality of individuals,” writes Gynther et al [1].  Such an explanation points to resilience, or the lack thereof: as sea levels rise, ecosystems near the coast or on islands cannot survive such severe storms as easily.

Here it is straight: human-induced global warming leads to changes in El Nino/La Nina oscillations leads to more severe storms leads to dramatic punishment to nearby ecosystems.  The melomys was caught in the middle.  All this happened quite quickly due to the low elevation of Bramble Cay, but this is an omen of what is in store for more heavily populated coastal regions as sea levels continue to rise and storms intensify.

Hope in Papua New Guinea

Australian scientists placed 900 small-mammal traps, set up 60 cameras, and combed the island for any sign of the mammal.  Usually these efforts turn up something, so the lack of a sighting indicates extinction.  But there may still be hope.  Some scientists believe the melomys living on Bramble Cay originated from the Fly River delta region of Papua New Guinea just to north, a less explored habitat that could be housing the last remnants of the species.  The scientists have recommended exploration of this area (if funding is available, of course).

The melomys is the first but not the last.  I never knew of this little creature before news of the search for their existence, but now the rodent serves as another reminder that the effects of global warming are happening now.  Scientists believe the finality of extinctions like these can be prevented if more resources are used to identify at-risk regions and relocate wildlife, not to mention reducing greenhouse gas emissions as quickly as possible.  The success of such a mission usually rests with finding enough money from politicians and governments who see the urgency of such pursuits.


Gynther I, Waller N, and Leung LK-P. “Confirmation of the extinction of the Bramble Cay melomys Melomys rubicola on Bramble Cay, Torres Strait: results and conclusions from a comprehensive survey in August-September 2014.” Unpublished report to the Department of Environment and Heritage Protection, Queensland Government, Brisbane, 2016.

Howard BC. “First mammal species goes extinct due to climate change.National Geographic, June 14 2016.

Figure Credits

Figure of Bramble Cay melomys courtesy of Ian Bell via Wikipedia

Posted in Climate Change, Current Events, Environment | Tagged , , , , , | 1 Comment

Oil spill cleanup secrets of Gulf Coast bacteria


I’m excited to put up a guest post by Shayna Keyles this week! Shayna Keyles is a multi-discipline writer, editor, and marketer based in Oakland, California. You can reach her at or follow her on Twitter at @shaynakeyles.

This article was originally published by, which translates complex research findings into accessible insights on science, nature, and technology. Help keep GotScience free! Donate or visit our gift shop. For more science news subscribe to our weekly digest.

Bacteria have played a large role in cleaning up the Gulf Coast after the 2010 Deepwater Horizon oil rig explosion, but it is just now becoming clear how helpful these microbes have been. Microbiologists sequenced DNA from native Gulf bacteria and discovered genetic properties that make some of these microbes so well suited to the job of cleaning up oil.

The smallest (and largest) cleanup crew

Scientists noted the proliferation of native bacteria just weeks after the rig explosion began to leak 4.1 million barrels of oil into the Gulf of Mexico. The bacteria appeared to consume both the oil and some of the dispersants used to help break up the spill.

A research team from the University of Texas at Austin, led by Brett Baker, assistant professor in the Department of Marine Science, and Nina Dombrowski, a postdoctoral researcher in Baker’s lab, set out to discover why bacteria were able to proliferate in such conditions. They collected live samples from the site of the spill and sequenced the genetic material from numerous bacteria in order to study bacteria’s genetic potential for cleaning an oil spill.

The bacteria that Baker and his team studied are typically not abundant until they are exposed to oil, at which point the populations tend to grow. This indicates that the bacteria are consuming the oil. The research team wanted to decode which parts of the oil were being consumed and how. Oil is a complex material, consisting of hundreds of chemical compounds, but the scientists focused their efforts on two compound groups that the bacteria may be responding to.

“Oil is extremely complicated, but it has two major compounds: alkanes, which are relatively easy for bacteria to break down, and aromatic hydrocarbons, which are much trickier to get rid of,” says Dombrowski.

“Polyaromatic hydrocarbons (PAHs) are among the most toxic in oil and are among the most abundant,” Baker tells GotScience. “We focused on the way bacteria in the spill break those down.”

They found that many bacteria are more equipped to handle PAHs than previously thought: Many of the bacteria the team studied have hydrocarbon-degradation genetic pathways, in addition to the alkane-degradation pathways that were found in all of the bacteria the group examined.

Alcanivorax, for example, is a type of bacteria that scientists already recognize as an oil eater: It is known for consuming alkanes. But the group found genetic evidence that the microbe was capable of breaking down the PAHs the spill had left behind. The team was also able to add new types of bacteria, such as Neptuniibacter, to the list of oil eaters.

A community oil spill effort

A key point to take away from this study’s findings is that a flourishing bacteria community is capable of greatness. Not only did the genetic sequencing uncover how individual bacteria respond to oil, but it also suggested that the combined efforts of a large bacterial community could have an enormously positive impact on a spill area.

There may be hundreds of complex compounds found in an oil spill, but there are also hundreds of hungry microbes in the water ready to feast on alkanes and PAHs. And it seems that’s not all they’re hungry for: Some of the bacteria seem to feed on the dispersants used to clear away the oil spill.

Dombrowski notes, however, that not all dispersants are microbe friendly. As we gain a better idea of the genetic composition of these bacteria and how bacteria communities cooperate, we can develop bacteria-friendly dispersants that help humans and bacteria work together harmoniously. “We need to make sure our response to a spill doesn’t interfere with this natural response,” she explains.

Of course, it should be noted that we cannot rely on bacteria to clean up our water for us—we shouldn’t be spilling oil in the first place. But when these tragic events do occur, we can count on our bacterial brethren to help us out.


Dombrowski N. “Reconstructing metabolic pathways of hydrocarbon-degrading bacteria from the Deepwater Horizon oil spill.” Nature Microbiology, 16057, 2016.

Photo Credits

Figure of oil spill courtesy of Andreas Teske at the University of North Carolina – Chapel Hill

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The greening of Vancouver


Aim a normal camera at a city skyline and you’ll likely snapshot a bustling panorama of skyscrapers and the incessant activity that energizes city-dwellers.  But point a thermal camera at the same cityscape and you’ll see a different form of energy: hot yellows and reds pouring out of towering glass buildings and other structures.

Residential and commercial heating is one of many energy demands that cities around the world are trying to make more efficient.  Glass skyscrapers are especially poor at trapping heat and these reflective monoliths were built during past decades of growth and expansion that cared less about energy conservation.  But it’s not just rethinking heating: composting, sewage recycling, car-sharing, and many other innovative ideas could reinvent city living and decrease carbon emissions at the same time.  As described by a new article in Science, no city is pushing harder for the lead in this type of transformation than Vancouver.

Green Goals

Vancouver city officials have challenged themselves to become the greenest city on the planet.  What are the numbers behind this declaration?  The city hopes to reduce energy use and emissions from buildings by 20% by 2020 and require all new structures built after 2030 to have no emissions.  This is a courageous goal, one that will need not only loads of renewable energy but also ingenious changes to how cities fundamentally operate.

Green is by no means a new color for the city just north of Seattle in Western Canada.  The city officially labeled climate change as a threat in 1990 (what was your city doing back then?), and its reliance on hydropower has lowered its carbon emissions beyond any other major city in North America.  Even now, city planning entices citizens to live in the central part of the city, increasing population density and pushing down required resources per capita.

But more changes are on the horizon, bringing us back to the giant skyscrapers blazing red on a thermal image.  More than two-thirds of Vancouver’s energy is used to heat buildings, just one indication that eco-friendly population densities and some renewable hydropower is not enough.  Rethinking basic city processes and reinventing the new norm is the great hope in Vancouver.  Here are just some of the ideas underway concerning energy efficiency, waste management, and traffic control in the City of Glass.

  1. Getting tough on trash.  How well do you separate your garbage and recycling?  Do aluminum cans sometimes find their way into your paper bin?  If so, warning stickers and violation fees would find their way to your doorstep if you lived in Vancouver.  Garbage inspectors now patrol the streets, checking for correct waste separation.  But it’s about more than keeping paper and metals apart.  The city found that 40% of landfill methane, mostly coming from organic waste, was escaping into the atmosphere and contributing to greenhouse gas emissions.  Inspectors are now handing out green bins for citizens to toss out scraps like meat, bones, and rotten leftovers.  The waste ends up in composting facilities to both reduce the amount of organics finding their way to landfills and to provide soil for regional farmers.  The inspectors also hope to be more than hand-slappers.  “It’s our job to do face-to-face education,” Jez Figol, one of many inspectors who talks to residents about how to decrease their footprint.
  2. Heating from sewage. Instead of dumping sewage water, plants in Vancouver now extract the heat from the wastewater flow to reuse to heat buildings.  Wastewater runs through a giant strainer (imagine your kitchen colander on steriods) to remove large particles, then passes by a heat exchanger as big as a semi truck.  This exchanger pushes the heat back through pipes that run through many city buildings, providing hot water to about 6000 residences from one plant.  All from sewage waste!
  3. Rethinking transportation.  Traffic congestion plagues almost every city and Vancouver is jumping on the bandwagon of creating bike-friendly traffic patterns and easy car rentals.  Bike lanes have popped up across the city to encourage more people to pedal to work.  Car-sharing has also taken off, as city officials predict that every rental car removes up to 11 private cars from being on the road.  Finally, the city has incentivized mass transportation, which has put a strain on the system because of its rising popularity.  All of these improvements has made traffic control one of Vancouver’s biggest success stories so far, as the city as already met its goal of cutting kilometers driven per person by 20%.

The challenges of being first

Vancouver officials outlined most changes in a 2011 action plan to reduce emissions 80% by 2050.  Currently, emission have been reduced by 7% in about 4-5 years due to changes like the ones listed above.

Unfortunately, not all parts of Vancouver’s greenification are evolving as successfully.  Most skyscrapers are still leaking heat because they are nearly impossible to renovate.  “Glass curtain-wall buildings are terrible and expensive to retrofit,” says Sean Pander, who manages the Vancouver green building program.  The only option is to slowly tear down old buildings and build new ones with stricter codes for energy efficiency, which takes a long time.  The City Council has offered small financial incentives for voluntary improvements by private businesses, but the details, like where to relocate employees temporarily, have not been fleshed out.

There are other issues looming on the horizon that could muddle Vancouver’s green plans.  Most of these relate to conflicts of interest between the city and provincial or national level.  For example, provincial officials will soon determine whether an oil pipeline and natural gas export facility can be built  close to Vancouver’s port, which would make emissions skyrocket.  Such a conflict illustrates the unique challenge that city officials face when greening their cities, playing proud promoter of green policies to the public while working diplomatically with the other parts of Canadian government to allow them to succeed in their mission.

And then there are the paths to sustainability that only citizens can achieve.  On average, cities require a land footprint about 200 times larger than the city’s actual area.  Cities can enact as many innovative policies as they like, but this footprint can be significantly reduced only through individual citizen choices: what they eat, when they turn off their lights, how high they turn up their AC, and what renewable energy policies they support.  Cities can do their part, and it is tremendously hopeful to hear about officials that are so passionate to take the lead in going green.  Let’s hope citizens can match this passion and action with their own will and innovation to help turn cities green forever.  In the meantime, Vancouver continues to push the green innovation edge farther along, hoping others will follow.


Weiss, K.R. “Vancouver’s Green Dream.” Science352(6288), 918-921, 2016

Figure Credits

Thermal photo of Aqua Tower in Chicago courtesy of Jim D’Aloisio via Wikipedia


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Surfing the polar front: how black carbon reaches the Arctic

Black carbon aerosol is carbon dioxide’s darker accomplice.  Not as well known as the atmospheric molecule that has defined our global climate crisis, black carbon still plays a role in amplifying warming trends, particularly in the Arctic.  But how did it get there?  Experimental studies continue to find more of this light-absorbing pollutant in the Arctic than global climate models predict, keeping its origin a mystery.

A new article [1] in Scientific Reports provides a partial answer by improving the resolution of climate models and illuminating how small-scale phenomena can play a huge role in global weather patterns.  The conclusions get us closer to understanding just how our fossil fuel industry is forever changing the planet beyond 66 degrees N.

Two possibilities, zero answers

The incomplete combustion of fossil fuels, biomass, or agricultural waste creates black carbon.  These tiny bits of leftover carbon are classified as particulate matter smaller than 2.5 microns in diameter (PM2.5) and are associated with a host of negative health effects like heart or lung disease.  Developing countries like India or China are struggling mightily to manage local black carbon levels that are rapidly rising.

Unfortunately, degrading human health is not the only danger.  According to the EPA, black carbon is the most effective PM2.5 at absorbing solar energy, capturing a million times more sunlight per unit mass compared to carbon dioxide.  Now, imagine this pollutant finding a home on the snow plains of the Arctic.  Snow normally reflects sunlight efficiently to provide negative feedback countering the effects of global warming.  This is one of the Arctic’s sole defenses left to stop severe melting as temperatures rise.  But as black carbon accumulates in the Arctic and replaces snow-white with carbon-black, reflective surfaces transform into light-absorbing hothouses, amplifying warming trends and pushing the Arctic closer to its watery fate.

If black carbon normally arises from human combustive processes, how does it end up blackening the Arctic?  This is the question researchers are still trying to answer.  Computer climate models are one of the best tools to understand climatic processes.  Unfortunately, all of them underestimate black carbon levels in the Arctic compared to on-the-ground, experimental measurements.

Researchers expect two possibilities could account for the experiment-model discrepancy: 1) there are unknown sources of black carbon in the Arctic that we haven’t found and thus haven’t included in current climate models; or 2) the models aren’t accurately capturing how black carbon moves along atmospheric currents from mid-latitudes to the pole.  There is some evidence to support the latter.  Low-pressure systems begin at mid-latitudes and follow the polar front to the Arctic.  This provides a potential pathway for black carbon to arise in industrial centers in the Northern Hemisphere (U.S., Europe, China) and surf all the way to the top of the planet.  But global climate models have predicted that the polar front drops all the black carbon through precipitation far before the Arctic Circle.

A finer look

Any computational climate model must divide the planet into a grid of finite-size regions, defining the resolution of the model.  The size of these grid regions effectively sets a limit to what can be seen: models are blind to any behavior changing on length scales smaller than the grid size.  Previous models have used a resolution of 50 kilometers, but it is well known that a weather system like the polar front contains small vortices and quick temperature changes on a scale much smaller than this.  Knowing this, Sato et al. improved their model resolution by an order of magnitude, decreasing each grid region to a width of 3.5 kilometers. Results using this model provide the first answers to how so much black carbon could accumulate in the Arctic.

The figure below shows results from the same simulation done at three levels of resolution – 3.5 km, 14 km, and 56 km (top, middle, and bottom rows, respectively).  Comparing the simulations illuminates two major features driving black carbon transport to the Arctic that previous models could not capture: 1) small-scale vortices and 2) cloud formation.


The impact of vortices can be seen in the left part of the figure.  The gray-scale images on the left visualize the polar front by mapping liquid water mass across a region near the southern tip of the Arctic.  This type of graphic essentially describes the direction of wind currents in the front. The 56-km model only has sufficient resolution to describe a broad, candy-cane-like structure at the center of the weather system.  In contrast, the 3.5-km resolution model predicts smaller-scale vortices within the larger, curling system.  The researchers predict that these vortices impact how much black carbon can be transported over long distances, however this idea must be explored further in future work.

Second, and more importantly, the 3.5-km resolution model improved the description of cloud formation.  The 56-km model smeared cloud formation across most of the front, thus predicting more rain that would move black carbon out of the atmosphere and onto the ground before reaching the Arctic.  In contrast, the 3.5-km model predicted much sparser cloud formation and less precipitation, allowing more black carbon to reach the pole before being released by the clouds.

As a result of these two factors, the finer-resolution model predicts much more black carbon at latitudes near 60 degrees N.  This can be seen in the righthand side of the figure, in which green regions indicate much more black carbon than blue ones.  We now have an answer: industrial operations in the Northern Hemisphere, burning coal, oil, and biomass, are likely channeling black carbon to the Arctic via the polar front.

Not done yet

Despite this incredible step forward in understanding, the finer resolution model still underestimates experimental black carbon levels in the Arctic.  The authors admit that, even at this fine of a resolution, the model is probably missing even more detailed features controlling cloud formation and precipitation.  The only answer is better supercomputing power to support models with sub-kilometer resolution.

But this is science – every new answer provides a glimpse of how a little bit better technology could give us even more comprehensive understanding.  The trend – that we are closing the gap between experimental and modeled results – is the important and hopeful part.  Once we understand how black carbon arrives at the Arctic, we can finally begin the hard work of trying to stop the process.



[1] Sato  Y et al. “Unrealistically pristine air in the Arctic produced by current global scale models.” Scientific Reports6:26561, 2016.


Figure of model results courtesy of Reference 1



Sato, Y., Miura, H., Yashiro, H., Goto, D., Takemura, T., Tomita, H., & Nakajima, T. (2016). Unrealistically pristine air in the Arctic produced by current global scale models Scientific Reports, 6 DOI: 10.1038/srep26561

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