The Earth Story

Lake Kivu: Making the Most of a Deadly Situation

There are a lot of ways a volcano can kill you. Explosions, pyroclastic flows, ash that disrupts climate and growing patterns….and if you needed to add another to the list: exploding lakes. It sounds pretty dire, but some brilliant people with a knack for finding silver linings have come up with a way to turn one of these killers—exploding lakes—into an energy source. Lakes that sit near volcanoes can become saturated with carbon dioxide. The carbon dioxide collects at the bottom of the lake, and with the right trigger, is suddenly released in a dense cloud, asphyxiating most life in its path. Two of the most infamous of these eruptions both occurred in Cameroon just two years apart—Lake Monoun in 1984 and Lake Nyos in 1986(http://on.fb.me/17hOLeB).

These “limnic eruptions” were very mysterious at first—they were killers that hardly left a trace. Once scientists figured out what was going on, they realized exploding lakes could be quelled by releasing the carbon dioxide slowly (via pipes) instead of letting it build up.

Enter some scientists who realized they could make the most of an unfortunate situation. There is another African lake that is very saturated with gas and shows signs of prehistoric eruptions—Lake Kivu on the border of the Democratic Republic of Congo and Rwanda. Lake Kivu is much larger than both Lake Monoun and Lake Nyos, and it is believed to hold much more gas—except most of this gas is not carbon dioxide, it is methane. Methane is an energy source. Methane can fuel power plants. Methane can provide electricity to the millions of people who live around the banks of Lake Kivu.

The Rwandan government decided to take advantage of this. Working with the energy firm, Contour Global, the aptly named project KivuWatt began constructing power plants that made use of the methane trapped in the lake. . The gas is puled out of the lake for safety reasons, but rather than just being released, it is burned in a power plant as a fuel source. 

The first phase of the project came online a few years ago and operates a power plant that generates 26 megawatts of electricity, more than 10% of the installed electricity capacity in Rwanda. There are plans to continue expanding the facility to bring the generation capacity up to 100 megawatts, which would represent 1/4 of Rwanda’s electricity generation if completed.

-CM

For more information: http://bbc.in/1zMEH83 http://bit.ly/170FG9O http://bit.ly/1vFo5zo

Photo credit: The Advocacy Projecthttp://bit.ly/1vNtkgx

Plate Tectonics and Mussels

This picture was taken off the coast of the islands of Trinidad and Tobago in the Caribbean Sea. This is a huge bloom of mussels sitting on the bottom of the ocean. The research vessel Nautilus located this site while studying the ocean floor earlier this year. The system itself is a remarkable example of a connected system. Old oceanic crust is subducting beneath the Eastern Caribbean, causing the formation of the volcanic islands that dot the boundary between the Sea and the Atlantic. When oceanic crust is subducted, it bends downward, cracking and breaking the rigid plate. These cracks allow water from the ocean to penetrate and circulate, where they react with the rocks. The reaction between ocean waters and the type of rocks that make up the mantle produces a couple things: the mineral serpentine and the gas methane as a byproduct.

The methane gas leaks upwards from the reaction site, carried by hydrothermal fluids until it reaches the open ocean. In the open ocean, methane is a spectacular energy source for microbes; the microbes eat the methane and use it to grow.

A big microbial bloom would cloud these waters, but they’re utterly clear thanks to the mussels. These mussels are filter-feeders; they take ocean water in and digest tiny organisms that are in the water as their energy source.

This is a giant bloom of mussels in the ocean fed by a chemical reaction enabled by plate tectonics. A wonderfully interconnected system.

-JBB

Image credit: Nautilus Live https://www.facebook.com/nautiluslive http://www.nautiluslive.org/

These are little bubbles of methane that come up from decaying organic stuff deeper in the lake. In the winter, they get caught beneath the ice, and as the ice grows downwards it traps the bubble in place, building a trail down.

Ooh neat, underwater mud volcano

Methane created by plants being consumed by lava, and the burning of that methane when it reached the atmosphere, created the blue flames in this video taken just after the start of the Fissure 8 eruption at Kilauea in May.

epiclava_

New survey of US methane leaks

This image, produced by NASA, shows methane concentrations over the United States between 2003 and 2009. Methane is pulled out of the ground and burned as natural gas, but if it leaks into the upper part of the atmosphere it is also a strong greenhouse gas that contributes to climate change.

In the years 2003-2009, new drilling techniques were developed in the United States that released methane from reservoirs that were previously inaccessible. The basic technique involves drilling holes into gas rich units and pumping sand and fluid into these units at high pressure; the pressure fractures the ground and the sand holds open the fractures, allowing gas to flow out.

If methane is used as an energy source instead of coal, there is a possible economic and environmental benefit as each molecule of methane has far more energy than the same mass of coal and burning it releases far fewer pollutants, including far less CO2. However, because of how methane atoms interact with infrared light, methane is also a far more potent greenhouse gas than CO2, so small methane leaks can totally swamp the environmental benefits of natural gas over coal. Therefore, monitoring the amount of methane that leaks out of the drilling and transportation operations is hugely important.

The research shown in this image from a few years ago showed a couple of methane leak hotspots, including a large one associated with drilling in Colorado. Although they did not prepare as pretty of an image as this one, a new study was just published updating these results and characterizing leaks from other gas fields.

In 2015, a P-3 aircraft operated by the National Oceanographic and Atmospheric Adminstration (NOAA) sampled the gas plumes above these drilling sites. They measured the atmospheric chemistry, the isotopic composition of gases, and other gases like ethane that can leak out associated with the methane. They matched gases measured in the atmosphere to the composition actually measured in wells in the units, to make sure they were measuring the methane actually leaking out of the ground.

In some cases, like the bullseye on this plot, their measurements suggest substantial progress. The methane measured leaking from Colorado has declined dramatically since this image was published; nearly 40% lower than what was observed in this time period. This reduction could be due to better procedures, or it could be due to there simply being less drilling now due to the drop in gas prices.

However, other areas showed higher leak rates. This area in Colorado, the Hayensville Shale in Arkansas, and the Eagle Ford shale in Texas all showed leaks that were comparable to 2-3% of the total methane gas produced. These leak rates are high enough that any benefit to using methane instead of coal is almost certainly lost.

However, that wasn’t nearly the worst. In North Dakota, the Bakken formation is also being used as a gas source. The amount of natural gas measured in the air above this formation implied that 5.4% of the produced natural gas from this formation was leaking to the atmosphere during the measurement period.

Overall there has been improvement in gas leaks in many areas. In fact, there should be improvement in gas leaks – gas that leaks to the atmosphere can’t be sold, if it’s leaking it’s literally money leaking into the sky. The previous administration made a point of working with gas producers to help them cut their gas release rates, but so far it still is not enough. The leak rates in some fields are approaching the levels we need (<1%), but as the Bakken formation shows, there needs to be a continued effort from industry to cut down on leaks and that effort has a long way to go.

-JBB

Image credit: https://www.jpl.nasa.gov/news/news.php?release=2014-348

Original paper: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2018JD028622

Frozen Bubble Seeps

This image captures a scene that occurs throughout the Arctic regions of the world; frozen bubble chains.

This photo was taken in one of the lakes in Bering Land Bridge National Reserve. In these arctic lakes, organic matter from plants and animals that live during the summer sinks to the bottom and decays, gradually producing methane that seeps out of the sediments.

As the fall turns to winter, bubbles of methane rise up and intersect the downward growing ice, leading to these vertical trails. Several larger bubbles appear as well. The bubbles are largely filled with methane – when these lakes thaw in the spring, that methane is released to the air and there’s probably a brief time when the air right above each of these lakes is explosive. Don’t start a fire when these lakes are thawing.

-JBB

Image credit: Bering Land Bridge National Reserve (creative commons license) http://www.flickr.com/photos/bering_land_bridge/8289044534/

Flame bursts as lava flows over an old tree stump and ethane is released

Poles warmed more than models expected

56 million years ago marks the boundary between the Paleocene and the Eocene Epochs. At that time, there was a rapid climate change on Earth, with extremely high temperatures at the planet’s poles, comparable to the tropics today (https://tmblr.co/Zyv2Js1vvz8m2). It is thought that at the Paleocene-Eocene boundary there was a rapid release of carbon trapped in the oceans and this triggered rapid climate change by increasing greenhouse gas abundances.

This picture shows a shell of one foraminifera, a single-celled organism that precipitates the mineral calcite from the ocean. Scientists have developed several ways to use the chemistry of this mineral as records of the temperature in the water that they formed from, specifically by measuring the abundances of the isotopes of each isotope of oxygen in the carbonate mineral.

This foram formed in the surface ocean at the North Pole during the Eocene. After it died, its shell found its way into sedimentary rocks and eventually it was measured by scientists from Yale University. They used the abundances of all 3 oxygen isotopes and the ratio of magnesium to calcium in forams like this to reconstruct the chemistry and temperature of the Eocene ocean.

They found that this foram, found at the North Pole, formed in waters that were at temperatures from 30–36°C. Not only is that vastly warmer than the nearly 0°C waters found at the North Pole today, but it is several degrees warmer than even the highest temperatures predicted by climate models for the poles at this time. Scientists base those models on the physics of the atmosphere, but they have to calibrate them based on the measurements geologists can give of what the Earth did millions of years ago.

These results imply that temperatures at the poles go up even more than predicted when there are huge spikes in atmospheric carbon dioxide, the poles are even more sensitive than scientists had previously predicted. This result, therefore, implies that the potential costs of increasing carbon dioxide in the atmosphere are even higher than scientists were predicting even last year.

-JBB

Image credit: Laura Cotton http://bit.ly/2E1etWg

Original paper: http://www.pnas.org/content/early/2018/01/12/1714744115

Antarctic methane.

Climate scientists are already worried about the possibility of a positive feedback loop between increased global temperatures and potential releases of methane (a greenhouse gas 100x more potent than carbon dioxide, which then oxidises to CO2 causing further warming) currently stored in melting permafrost or in clathrates at the bottom of the sea (see http://tinyurl.com/mc4tj77 and http://tinyurl.com/m4jpkse). New research recently published in Nature suggests that a further reservoir is at risk of exposure if the Antarctic ice sheet starts to melt.

As the ice sheets started to form from the Oligocene onwards, they overran many sedimentary basins upon which both marine and terrestrial life had thrived throughout the Mesozoic and early Cainozoic eras. All this organic matter got buried with the sediments as new layers of sediment piled on, and then covered in ice. Underneath the sheets, anoxic conditions promote (just like in permafrost or the production of natural gas) the bacterial decomposition of these organics into methane.

If the ice shrinks, these basins may well become exposed, and release a previously unexpected reservoir of methane into the atmosphere, exacerbating global warming. They estimated Antarctica's methane content at ten times the size of the northern permafrost reservoirs. Part of the ice sheet also overlies the sea floor, being grounded below sea level. More methane could well lurk as clathrates beneath this area, predicted to be the first to go as warming starts to bite.

Loz

Image credit: Vincent van Zeijst.

http://news.ucsc.edu/2012/08/antarctic-methane.html

http://www.theguardian.com/environment/2012/aug/29/antarctica-methane

Original paper, paywall access: http://www.nature.com/nature/journal/v488/n7413/full/nature11374.html

What bubbles beneath the ice

At a first glance, it appears that these frozen waters are bursting with some sort of strange sea creatures (a jellyfish, perhaps), but in fact, they are filled with innumerous methane frozen bubbles. Banff National Park in Alberta, Canada, hosts several lakes that freeze in the winter, capturing within bubbles of methane, which is a highly flammable gas. These eerie bubbles are formed when dead organic matter (such as plants and animals) tumbles into the water and then sinks to the bottom. What happens next is that bacteria present in this environment consume that dead organic matter and then release methane. As methane attempts to escape, it turns into white floating bubbles and gets trapped underneath the ice.

Methane is fairly inoffensive when escaping from the surface of water, however, these pretty bubbles can cause an explosion if ignited, so care is recommended. If you are ever in Banff National Park to check out the methane bubbles, you should probably just take some pictures, enjoy the view and leave the ignitions to the experts.

It is well known that methane is not only formed in Canadian lakes, but also throughout the Artic region, but permafrost has been decreasing and this means that methane previously trapped in there is being progressively released into our atmosphere. This is something that worries climate scientists and concerns us all, since methane is a very powerful greenhouse gas that contributes to global warming.

Su

Sources: http://nyti.ms/2y6WQAO http://bit.ly/LqlUJa http://bit.ly/2bQgLd1

Photo credits: http://dailym.ai/1yD2W35 - photos by Paul Zizka/Caters News Agency_ _

Underwater Raman. This is pretty frickin’ awesome.

Windy view of the eternal flame at Darvaza Gas Crater, Turkmenistan

Methane eating bacteria

In September of 2015, this site near Los Angeles became a major industrial accident. This is one of the well pads at the Aliso Canyon Natural Gas storage facility – a site that pumps natural gas into the ground and holds it so that it can later be shipped around the city. Starting in that September, one of the underground storage well paths ruptured, allowing large amounts of methane to leak upwards.

That methane first leaked through the soil, then traveled up into the air. Communities near the leaking pad were evacuated after complaining of breathing problems, and the methane leak became one of California’s largest air pollution sources until it was finally plugged in February of 2016.

The fact that the methane traveled through the soil created an unfortunate, if interesting, opportunity to do science. Methane is a major energy source for microbes – if they get ahold of methane, they can react that methane with oxygen in the atmosphere to generate energy. Starting in December 2015, a team from Victoria Orphan’s lab at the California Institute of Technology began sampling soil at the site to observe how the community of microbes in the soil changed when the soil suddenly was flooded with a new and ample energy source.

Their team uses techniques that you might recognize from some of the best biology labs on Earth. After sampling soil at the site, they took cores back to their lab and counted the different species of bacteria living at the site to see how they changed when the methane leak was present. They then processed those samples to see what specific organisms and metabolisms could be recognized, and in fact they appear to have identified bacteria that could process the methane into energy using a never-before-studied enzyme.

Natural gas leaks around the world can send methane – a potent greenhouse gas – into the atmosphere. Understanding the different organisms that can consume methane allows researchers to better understand the global methane budget. Methane abundances in the atmosphere have increased rapidly in recent years and therefore figuring out the metabolic pathways that life uses to consume methane is a major part of figuring out how to manage this gas on the ground.

-JBB

Image credit: Earthworks https://flic.kr/p/BrHJiZ

Reference: http://www.caltech.edu/news/lessons-aliso-canyon-53317

Source of skyrocketing atmospheric methane

Molecules of methane in the atmosphere behave as a potent greenhouse gas – they absorb light at wavelengths where the atmosphere would otherwise be transparent, converting that light into heat and forcing the atmosphere to warm up in order to remove energy from the surface. Atmospheric methane concentrations have been increasing for decades due to changes caused by humans, including agriculture, changes in land use, and use of methane as the main ingredient in natural gas.

In samples of atmosphere from ice cores, methane abundances in the atmosphere are typically between 500 and 750 ppb, varying with the large-scale climate shifts on the planet. Since the year 1800 though, methane concentrations have spiked to over 1800 ppb – multiplying by a factor of 3. Despite this rapid runup, in the first decade of this century it appeared as though humanity was making progress controlling this gas. Atmospheric methane first reached 1800 ppb during the year 1998, but from 1998-2007 the total methane measured in the atmosphere was nearly constant.

However, starting in 2008, this pattern changed again, and methane concentrations began increasing rapidly again, reaching over 1850 ppb this year. This methane spike has correlated with increased drilling for natural gas particularly in the United States; so expecting gas exploration to be the sole cause has been a tempting hypothesis. However, when methane is leaked to the atmosphere there are a number of microbes that rapidly use it for energy, so the exact source of the big methane boost in the atmosphere still needed identification. Recent research suggests that in fact gas exploration itself has not been the cause of the recent surge in methane, but that in fact the cause may be even more worrisome.

Carbon has 2 stable isotopes – one with six neutrons and one with seven neutrons. Different reservoirs for carbon, including organic life today, carbonate rocks, and fossil fuels each have different ratios of these 2 isotopes, meaning that with detailed enough measurements scientists have some ability to use them as a fingerprint.

A team of scientists from countries around the world worked on this problem using samples taken as part of a global sampling effort run by NOAA, the United States National Oceanographic and Atmospheric Administration. Samples of the atmosphere were taken, methane abundances were measured, isotope ratios were measured, and the exact location of each sampling site was processed to best characterize the source of the methane.

Once the researchers had enough data, they realized that natural gas leaks could not be the cause of the increasing methane after 2007. Natural gas has more carbon-13 than modern organic matter and the methane escaping to the atmosphere was missing this heavy carbon. The lower carbon 13 abundance fingerprinted modern life as the source of this methane. Something was changing in the biosphere, but what? The next step for the scientists was to test what portion of the Earth was generating this methane pulse. If the methane was coming from agriculture – say for example being released by farming and animals – then the methane spike should correlate in latitude with the heaviest farming activities. This hypothesis was also found to be untrue, as were other ideas they tested such as reduced use of methane by surface organisms. After eliminating other possible hypotheses, the scientists concluded that the methane entering the atmosphere today is coming from the tropics.

This image is a mangrove swamp. There are huge areas of submerged wetlands like these all around the tropics and they are extremely sensitive to changes in water temperature, salinity, and water level. The soils in these swamps have very little oxygen, so if the conditions change and those soils are disturbed, large amounts of methane can be released rapidly.

The increased methane in the atmosphere is coming from latitudes where these swamps are abundant, it matches them in isotope composition, and it turns out there is also some correlation with large scale weather events in the tropics such as the El Niño cycle. Swamps in the tropics have, over the past 9 years, started releasing much more methane than they were in previous years.

This finding is particularly concerning because the amounts of carbon locked in these swamps worldwide is enormous – enough to drive major ongoing warming if it is released. Large releases of methane from these systems imply that the weather conditions at these sites are changing more rapidly than the swamps can keep up. While this measurement doesn’t tell the state of any specific swamp, it suggests that worldwide the stresses on this important ecosystem are increasing. Release of carbon from these systems is a major feedback – as the earth warms and they become less stable, even more carbon can be released, making the atmospheric warming even more intense and destabilizing even larger areas..

While the result of this work suggests that natural gas production is not the direct cause of these methane increases, a fingerprint suggesting that gas production was driving them would almost have been more comforting. Instead, these results suggest that major systems on Earth are being put under growing stress even compared to just a few years ago, a particularly troubling sign of rapid environmental change.

-JBB

Image credit: NOAA http://bit.ly/2h4Wjuu

Reference/Original paper: http://onlinelibrary.wiley.com/doi/10.1002/2016GB005406/full http://bit.ly/2hBm6sW