Part of Keystone XL pipeline to go ahead

(Image: KPA/Zuma/Rex Features )

Remember the controversial Keystone XL oil pipeline, which Barack Obama rejected last month because environmental concerns hadn't been properly addressed? Well, a chunk of it is going to be built regardless - with Obama's approval.

Canadian company TransCanada will build a pipeline running from Cushing, Oklahoma to Houston and Port Arthur in Texas. According to a statement:

...what had been the Cushing to U.S. Gulf Coast portion of the Keystone XL Project has its own independent value to the marketplace and will be constructed as a stand-alone Gulf Coast Project, not part of the Presidential Permit process. The approximate cost is US$2.3 billion and subject to regulatory approvals, we anticipate the Gulf Coast Project to be in service in mid to late 2013.
In the same statement, TransCanada also announced that it would reapply to construct the remainder of the proposed pipeline.

Given the US government's support for the Oklahoma-Texas pipeline, it seems likely that the rest of Keystone XL will eventually be approved.

The Oklahoma-Texas pipeline will not cross the US-Canada border, so it does not need State Department approval. The Edmonton Journal points out that it still needs to be approved by the U.S. Army Corps of Engineers under the Clean Water Act, though.

The Oklahoma-Texas section does not include the most controversial part of Keystone XL, which would pass through Nebraska. Environmentalists have raised concerns about the sensitive Nebraska Sand Hills ecosystem, and the nearby Ogallala aquifer that supplies drinking water to people in eight US states .

The Associated Press quoted White House press secretary Jay Carney as saying that Obama approved of the decision to press ahead:

Moving oil from the Midwest to the world-class, state-of-the-art refineries on the Gulf Coast will modernise our infrastructure, create jobs, and encourage American energy production.
Bloomberg explains that the new pipeline will relieve a glut of oil that has built up in Cushing:

The pipeline will help relieve oversupplies that have accumulated in the US Midwest because of a lack of pipeline capacity to carry the oil to refineries on the coast. Cushing is the delivery point for crude oil traded on the New York Mercantile Exchange. A lack of pipeline capacity between Cushing and the Gulf Coast, where most refineries are located, has caused U.S. oil to trade at a discount to imports.
If it goes ahead, Keystone XL would run alongside the existing Keystone pipeline, which carries oil from Alberta, Canada, to Cushing and also to sites in Illinois, and extend it all the way south to the US Gulf coast. The existing and proposed pipelines are shown in this map on the TransCanada website.

Apart from the risk of leaks, Keystone XL is also controversial because of its impact on the climate. The oil it would carry is derived from tar sands, so extracting and processing it requires a lot of energy. As a result, oil from tar sands produces more greenhouse gas than conventional oil.

Last week the European Union voted on a proposal to label fuel oils according to their carbon footprint, which would have effectively banned the import of oil from tar sands into Europe. However the vote ended in deadlock, so the final decision will not come for several months.

Spacecraft assembled for first private shot to ISS

Image: SpaceX)

A private spaceship is one step closer to launching to the International Space Station. SpaceX's Dragon cargo capsule and Falcon 9 rocket have been assembled in Florida, SpaceX CEO Elon Musk tweeted on Saturday.

The two will probably launch in late April on an uncrewed mission to test the Dragon capsule's ability to rendezvous and dock with the station. According to Jeff Foust in The Space Review:

The Dragon will carry some nonessential "demonstration cargo" that will be transferred to the ISS. It will also be loaded with station cargo for return to Earth.

Observers will be watching the launch with bated breath. In the wake of last year's retirement of the US space shuttles, the main means of ferrying supplies to the orbital outpost is Russian Progress cargo ships. Unfortunately, a Progress launch failed last year, temporarily grounding all missions to the station. Dragon would be the first commercial craft to attempt to visit the outpost (take an interactive tour of the Dragon capsule).

Earlier this month, NASA's space station programme manager Mike Suffredini said the Dragon launch would occur no earlier than 20 March. "There are no big problems being worked out but a lot of little things to wrap up," he said. Now software checks have pushed the launch back, probably to late April, Foust reports.

A giant among moths

(Image: Sandesh Kadur/naturepl.com)

ATLAS moths (Attacus atlas) are giants of the insect world. They are the largest moths known to exist, with a 25-centimetre wingspan. A common sight in south Asia, they can be found from India all the way to Papua New Guinea.

Photographer Sandesh Kadur spotted this beauty on a trip to document the biodiversity of the eastern Himalayas. Early one morning he was driving through Arunachal Pradesh in the far north-east of India, when he rounded a bend in the road and saw "a ginormous moth" sitting by a pothole.

He got out to take photos, and as he did so the moth went into a defensive posture, spreading its wings and leaning forward to make itself look as big as possible. It remained still for several minutes, so one of Kadur's colleagues was able to step behind it; the moth's wingspan was wider than his face.

As well as the moth's intimidating size, the striking patterns on its wings may also ward off predators. Venomous animals like wasps and poison frogs use similar colours to deter animals. In fact, in China the atlas moth is known as the snake's head moth, because the patterns on the tips of its wings look slightly like the heads of snakes.

Kadur eventually decided that the moth wasn't safe sitting in the road, so he manoeuvred it to the side. Some people are scared of moths but these monsters only live for a couple of weeks as adults and don't eat at all. All their feeding is done during a voracious larval stage when they go from egg to pupa in just four to six weeks - these are very hungry caterpillars indeed.

Counting penguins from space

(Image: DigitalGlobe)

Counting emperor penguins (Aptenodytes forsteri) cannot be easy. They spend much of their time in the Antarctic Ocean and when they do come on land it's for winter in some of the remotest, coldest and windiest places on Earth.

Fortunately, a team from the British Antarctic Survey (BAS), University of Minnesota, Scripps Institution of Oceanography and the Australian Antarctic Division have found an easier way to keep tabs on the penguins - satellite images.

Using images of the colonies like this one, the team counted a total of 595,000 birds, much higher than previous estimates of 270,000 to 350,000. The satellite images also helped the researchers to find seven previously unknown colonies, taking the total to 44.

Peter Fretwell from BAS said: "This is the first comprehensive census of a species taken from space."

Glaciers in Karakoram have grown since 1999

(Image: Kelly Cheng Travel Photography/Getty Images)

In one corner of the world, there is more ice today than there was 10 years ago. New satellite data shows that the glaciers in the Karakoram have grown slightly over the last decade, bucking the global trend. We don't know why it has happened - but it's important to keep it in perspective.

The Karakoram is a large Asian mountain range next to the Himalayas. It includes K2, the second tallest mountain in the world. While the Karakoram is home to many of the world's glaciers, there is little data on their behaviour because it is so remote.

Now Julie Gardelle of the University of Grenoble in France and colleagues have used satellite data to build two pictures of the Karakoram's glaciers, from 1999 and 2008. That tells us how they have changed.

Gardelle found that the glaciers grew slightly, adding an extra layer of ice that equates to an 11-centimetre thickness of water every year. By taking up this extra water, the glaciers prevented about 0.01 millimetres of sea level rise per year.

Shuttle engines in rocket custom shop

THEY may bring to mind Daleks, the sinister cyborg race from the British TV series Doctor Who, but during their working life they belched fire into the flame trenches at the Kennedy Space Center near Orlando, Florida. Now a curious calm has fallen on these formidable beasts - the engines from the recently retired space shuttles Atlantis and Endeavour - as they await a new role in human space flight.

Stored alongside nine others - those from Discovery, plus spares - in the engine shop at Kennedy, these Pratt & Whitney Rocketdyne liquid-fuelled motors are awaiting transport to NASA's Stennis Space Center in southern Mississippi. There, they will be tested and hopefully reused in NASA's future heavy-lifting rocket, the Space Launch System (SLS), which is designed for missions beyond Earth orbit.

It is all part of NASA's plan of learning as much as possible from the shuttle programme and feeding that knowledge, and technology where possible, into the next generation of "shuttle-derived" rockets. Both variants of the SLS reuse space shuttle main engines - and both could feature shuttle-style solid rocket boosters, although one also has the option of liquid-fuel boosters.

Goodbye fly-by for space shuttle Discovery

(Image: Sutherland Erin/ABACA/Press Association Images)

Piggybacked on a modified Boeing jumbo jet, and stripped of its heavyweight rocket engines and fuel tanks, the space shuttle Discovery flew its final trip today.

In four spectacular fly-bys of central Washington DC, the plane's pilot played to the crowds on the way to Dulles airport, from where Discovery will be delivered to its new home, the Smithsonian's National Air and Space Museum. Here, the space shuttle will join the Wright Flyer, X-15 and SpaceShipOne as yet another trophy exhibit.

Scientists have good reason to love Discovery: it launched the Hubble Space telescope in April 1990, and serviced it in 1997 and 1999 - giving us our best ever window on the heavens.

Eggy arms race

(Image: Claire Spottiswoode)

The cuckoo finch isn't a true cuckoo but it too lays lookalike eggs in the nests of other species, which hatch and are raised by an unsuspecting host parent.

The arrangement results in an arms race between the birds: cuckoo finches (Anomalospiza imberbis) evolve to become better at imitating host eggs, and hosts to become better at detecting the fakes.

A collection of eggs from wild cuckoo finches and one of its hosts, the tawny-flanked prinia (Prinia subflava), demonstrates just how quickly the arms race can drive evolution.

Over the last 40 years the prinia has responded to its invaders by evolving a wider spectrum of colours and patterning. The present-day sample of prinia eggs, shown in the outer ring, demonstrates this. The inside ring show the smaller range of colours and patterns produced by cuckoo finches.

Individual prinias lay very different-looking eggs, says Claire Spottiswoode of the University of Cambridge. This makes it less likely that a cuckoo egg will match. Prinias have also shifted their eggs toward the olive side of the palette over the last 40 years, a colour cuckoo finches currently find hard to imitate.

Spottiswoode expects that in future years the cuckoos may well adopt the olive palette in response - and in turn, prinia fashion may be on to some new hue.

The fish that almost blew Newton's career

(Image: Royal Society)

Give an angler the time of day and chances are they'll have a story to tell about the one that got away. When the Royal Society chose to publish a book on the natural history of fish in 1686, they came perilously close to letting slip one of the biggest scientific catches of all time - Newton's Principia Mathematica.

John Ray and Francis Willughby's 1686 book Historia Piscium must have seemed like a good bet - the illustrations, like this one of a flying fish, were impressive. And other natural history books - such as Robert Hooke's 1665 book Micrographia - had become bestsellers.

But Historia Piscium bombed, leaving the society so strapped for cash that it fell to one of their clerks, the scientist Edmund Halley, to raise the money needed to publish the Principia.

Photo exhibition brings new light to ocean depths

(Image: Sandra J. Raredon, Division of Fishes, NMNH)

ON 17 January 1978, this tropical hatchetfish was minding its own business about 850 metres below the surface of the North Pacific Ocean when it was captured, killed and taken to become part of the Smithsonian Institution's fish collection.

Now its portrait is part of the "X-ray Vision: Fish inside out" exhibition at the Smithsonian National Museum of Natural History in Washington DC, which runs until 5 August. Specimens from the museum's collection, including this Argyropelecus lychnus, were imaged using a digital radiographic machine that doesn't need film. Specimens are placed on a digital sensor and zapped with X-rays. Other species to feature include the winghead shark, the pancake batfish and the coelacanth, often referred to as a "living fossil".

Seeing the hatchetfish as a ghostly X-ray image seems appropriate, given that in life the species has bioluminescent camouflage. Hatchetfish elude deep-sea predators by using counterillumination. Photophores on the underside of the body emit light that matches the feeble illumination penetrating from the surface, so when looked at from below the fish merges with the surface.

The fish also has very large eyes. "This is typical of many such fish that live in the ocean's twilight zone where light penetration is diminished," says Lynne Parenti, curator of fish at the museum. In the mouth can be seen needle-like teeth that curve inwards. "Marine hatchetfish migrate towards the surface at night to feed on plankton, small fish and invertebrates," she says.

The X-ray has one last secret to reveal: those white chunks in the centre of the image are the undigested remains of the fish's last meal.

Ear wax improves underwater hearing - for whales

Image: Maya Yamato, Woods Hole Oceanographic Institution)

We're all familiar with the songs of baleen whales from wildlife documentaries or piped through the speakers in new age shops. Their eerie calls are part of the underwater soundscape with radar and motors joining the biological throng. But if we were to join the whales in their own habitat we would probably make little sense of the noises because our ears are not adapted for underwater use.

Baleen whales, of course, have no trouble hearing underwater and new research has helped us understand how - specialist fat bodies associated with their ears.

Using MRI and CT imaging techniques as well as dissection, Maya Yamato and other scientists at Woods Hole Oceanographic Institution (WHOI), examined the anatomy of heads of seven minke whales. The computer image above was generated of a whale's skull using this data and shows the fat bodies in yellow leading to the whale's ear in purple deeper in its head.

Yamato and colleagues propose that the fat bodies provide a transmission pathway for sounds from the external environment to the auditory organ (see Anatomical Record). Baleen whales share this feature with toothed whales, where it was assumed the fat was part of the sophisticated echolocation system used in hunting. Because baleen whales graze rather than hunt, they do not need finely-tuned echolocation and the discovery of these fat bodies in their ears suggests it is a feature from the toothed and baleen whales' shared ancestor and is necessary for their hearing.

Mining asteroids could boost space exploration

(Image: Bryan Versteg/spacehabs.com)

Talk of mining asteroids was once the preserve of corduroy-flare-clad, optimists of the Apollo era. Now the idea is making a comeback thanks to enterprising tech billionaires and a nascent commercial space industry.

The company Planetary Resources is due to outline today in Seattle, Washington, its aims to mine near-Earth asteroids for precious metals. "The resources of Earth pale in comparison to the wealth of the solar system," company founder Eric Anderson, also of Space Adventures, told Wired Science.

Anderson's co-founder is Peter Diamandis of the X Prize foundation, which runs competitions to stimulate privately funded space technology. The pair are backed by billionaires from Google, Microsoft and Dell and are advised by film director James Cameron and ex-NASA employees.

Planetary Resources says its first step is to launch a small fleet of space telescopes within the next few years to identify potentially valuable near-Earth asteroids. While asteroids are known to be rich in platinum, nickel and other precious metals that are steadily rising in value, it's still the start of a daunting task.

Water central to detailed asteroid mining mission plan

(Image: Planetary Resources)

Planetary Resources, the nascent billionaire-backed company that's planning to mine near-Earth asteroids, has revealed details of its first exploratory missions - and that it plans to mineice deposits as well as precious metals and minerals. The water could support life, or be split into oxygen and liquid hydrogen to make breathable air and rocket propellant, the firm says.

Though it will be many years before it reaches an asteroid, Planetary Resources has even begun advertising for 'asteroid miners'.

In a 24 April press conference in Seattle, Planetary Resources cofounder Eric Anderson - the entrepreneur behind the civilian spaceflight firm Space Adventures - says the first phase is to launch an unspecified number of cheap space telescopes into low Earth orbit to identify potentially resource-rich near-Earth asteroids.

He says development of these "Leo" satellites has already begun and that they plan to launch the first within two years. The firm - which counts Google co-founder Larry Page and Peter Diamandis of the X-Prize Foundation among its investors - also expects to rent out cosmic viewing time on the telescopes to astronomers.

Technicolour clones reveal how hearts build themselves

(Image: Vikas Gupta, Duke University Medical Center)

Our cardiac muscles work without rest until we die, but how does a heart form in the first place?

Vikas Gupta and colleagues at Duke University Medical Center in Durham, North Carolina, have found that zebrafish's hearts are formed from a starting point of just eight single stem cells, one or two of which often dominate the heart's growth.

The researchers followed the heart development using a colour labelling technique that allowed them to track the progeny of each of the starter cardiomyocytes, from embryo to adult.

In this image, a large swathe of cardiac muscle cells (shown in green) - all clones of a single starter cardiomyocyte - expand over the surface of smaller swathes of clones created by other starter cells (shown in purple, red, blue and yellow). Each colour represents the progeny of a different starter cell.

"It was completely unexpected," Gupta says. "I thought the wall would simply thicken in place, but instead there was a network of cells that enveloped the ventricle in a wave."

Researchers may one day be able to channel this growth process in order to help damaged or failing human hearts grow new muscle, suggests Gupta's colleague Ken Poss.

Journal reference: Nature, DOI:10.1038/nature11045

Early galaxies are strangely stuffed with stars

(Image: NASA/ESA/Anderson/van der Marel)

In this image of the Milky Way star cluster Omega Centauri, bright stars have been coloured blue, faint ones red. For more distant galaxies, though, faint stars are impossible to see. Now it turns out some of the most distant galaxies in the universe are more packed with stars than astronomers expected.

The only information galaxies give astronomers comes from the light of their stars. But stars don't carry all of a galaxy's mass. Some of the mass is tied up in invisible dark matter, which can't be measured directly.

To get around that, astronomers generally estimate a galaxy's mass by charting how its stars move with respect to each other. They compare the amount of visible mass to the total mass, and assume the rest can be made up with dark matter.

"To estimate exactly what is the mass that they have, we always use this conversion factor, to convert light into mass," says University of Oxford astronomer Michele Cappellari. "The conversion we used for many decades was wrong."

Cappellari found that the relationship between visible light and stellar mass is not the same for all galaxies -- it varies from galaxy type to galaxy type. The mismatch was worst for the most distant galaxies, which are three times more star-filled than expected; astronomers had not been counting faint stars - like the red ones above - in these distant galaxies.

That raises a new cosmic conundrum: when we see distant galaxies, we see them as they were when they were very young, but how did these star-stuffed galaxies get to be so big so early on in their lives? "They need to grow faster than people thought," Cappellari says.

Older than Giza – ancient burial chamber revealed

(Image: Centre for Digital Documentation and Visualisation)

EVEN 5000 years ago, Britons were an understated bunch. About 250 years before work began on Egypt's ostentatious Great Pyramid of Giza, the early settlers of Orkney, off the north coast of Scotland, were building impressive stone chambers of their own - and burying them under mounds of dirt. Now, intensive laser scanning makes it possible to virtually peel away the mud, revealing one of those chambers in all its glory.

This is Maeshowe, a 3.8-metre-tall tomb chamber reached via a narrow passage 11 metres long. Maeshowe is one of several Neolithic monuments that comprise the Orkney UNESCO World Heritage Site. It was scanned by a team from the Glasgow School of Art's Digital Design Studio and the government agency Historic Scotland. The team is scanning 10 World Heritage Sites, five of which are in Scotland, for the Scottish Ten project. "We scanned Mount Rushmore [National Memorial] in the US in 2010," says Lyn Wilson of Historic Scotland.

All the sites are tourist attractions, which can make conserving them a challenge. The scans, accurate to within 6 millimetres, will form an invaluable record to monitor future wear and tear.

Not all damage made by visitors is unwelcome, though. A thousand years ago, Orkney was under Norwegian rule and Maeshowe was plundered. The robbers left behind the largest collection of runes known outside Scandinavia, carved into the stone. These, too, have been laser-scanned in sub-millimetre detail. That's pretty impressive for 1000-year-old graffiti.

More images are available on the Scottish Ten website.

Dramatic storm clouds win photography prize

(Image: Mitch Dobrowner, US, L'Iris d'Or, professional winner, Landscape, Sony World Photography Awards 2012)

This photo taken in Dundee, Texas, shows a supercell storm, which are formed when updrafts create convective rotating movements within a cloud. Supercells are associated with severe weather such as tornadoes, which are common in Texas and other southern US states and cause widespread damage.

Yesterday, fine art photographer Mitch Dobrowner was announced as the winner of the L'Iris d'Or for his series of dramatic black-and-white photos of weather taken in the plains of the American South.

Dobrowner's series of photos and the other winners and entrants of Sony World Photography Awards are on display at Somerset House in London until 20 May (entry £7.50, concessions available).

Another casualty in the war of elephants and humans

(Image: Heri Juanda/AP/Press Association Images)

It is a story all too common - animals being squeezed out by people destroying their habitats for farmland. Then the hungry animals return to that land in search of food and the humans are surprised, responding with further destruction.

This dead Sumatran elephant was found this morning on the edge of a palm oil plantation in Krueng Ayon, Aceh province, Indonesia. Despite elephants enjoying protected status from the Indonesian government, this one is the victim of a suspected poisoning.

Sumatran elephants are a subspecies of the Asian elephant that inhabit the lowland forests of Sumatra, Indonesia. The subspecies is classified as critically endangered by the International Union for Conservation of Nature and it is estimated that fewer than 3000 remain in the wild on Sumatra. According to the IUCN, in the past 75 years natural forest cover in Sumatra has declined by 66 per cent and the remaining area is in fragmented patches too small to support elephants. Conservation organisations are working with the government to expand the areas of forest protected against clearing.

Starving elephants are known to raid villages and trample crops, which is probably why this one met the fate he did.

Taser dart pierces skull and spikes brain

(Isabel Le Blanc-Louvry and colleagues, Forensic Science International)

Two research papers published this week throw further light on the health risks of the Taser stun gun. This striking image shows the central issue examined in one of the papers: what happened when a barbed dart fired by a police Taser struck a 27-year-old man on the side of the head. Although Isabel Le Blanc-Louvry and colleagues at the department of forensic medicine at Rouen University Hospital in France do not reveal when or where this occured, they say the victim had been drunk and resisted police requests for his ID. The police fired the pneumatically powered Taser to incapacitate and subdue him - but somehow nobody noticed a dart remained stuck in his head, until he later went to hospital complaining of a persistent headache.

In the ER, the dart was found to "have penetrated the frontal part of the skull and damaged the underlying frontal lobe", the team report in Forensic Science International. "We observed that the length of the Taser dart is sufficient to allow brain penetration," they write. The man made a full recovery.

Why Jupiter's moon Ganymede is an exciting destination

Ganymede, here we come. A €1 billion mission to place spacecraft in orbit around Jupiter's largest moon - also the largest in the solar system - has received the green light from the European Space Agency.

Called the Jupiter Icy Moon Explorer, or Juice, the spacecraft will fly past two other Jovian moons - Callisto and Europa - and end its journey in orbit around a third, Ganymede.

While Europa, a water world with the potential to support life, has grabbed more of the limelightover the years, Ganymede,with its own ocean, auroras and oxygen, may have even more to offer, says Emma Bunce, a physicist at the University of Leicester, UK, and a member of the science team behind Juice.

Greenland glaciers on the move 19:00 3 May 2012

(Image: IceBridge Science Team/NASA)

This glacier in east Greenland is one of over 200 that flow from the Greenland Ice Sheet. The latest measurements of the glaciers' movements suggest that they are not accelerating as much as feared. This in turn suggests that sea level rise this century will be well short of the worst-case scenario.

Ice from Greenland and west Antarctica is one of the biggest sources of uncertainties when scientists try to forecast how much sea levels will rise this century. Some of Greenland's glaciers have accelerated in recent years, giving rise to fears that they will raise sea levels significantly.

Based on the physics of ice sheets and glaciers, a 2008 paper argued that a rise of 2 metres in sea level is the most we could possibly see by 2100. That includes a contribution of between 9.3 and 46.7 centimetres from Greenland, depending how much the glaciers speed up and dump ice into the sea.

Twila Moon of the University of Washington, Seattle, and colleagues have recorded the movements of almost all Greenland's glaciers from 2000 to 2010.

They found an enormous amount of variation, with glaciers that terminate on land moving much slower than those terminating in water. Glaciers in the north-west accelerated steadily while many of the others maintained the same speed.

So far, the overall acceleration of Greenland's glaciers is well below the worst-case scenario, which would require them to speed up by an order of magnitude. Of course we don't know what the ice will do next, and even a smaller sea level rise will cause widespread problems in low-lying countries like Bangladesh. Also, sea level will keep rising long after 2100. But if this isn't good news, it's at least news that's rather less bad.

Spinning space telescope's view of a pulsar

(Image: NASA, DOE, International Fermi LAT Collaboration)

When dancers spin on the spot, they choose a point in front of them and try to keep their eyes fixed on it for as much of the spin as possible.

It can't be so easy to keep the Fermi Gamma-ray Space Telescope trained on one spot in the sky as it maps the universe. Fermi orbits the Earth every 95 minutes while rocking between the north and the south on alternate orbits, On top of this, the satellite also completes one rotation every 54 days to keep its solar panels facing the sun.

This image traces Fermi's view via its Large Area Telescope of the gamma rays emitted by the Vela pulsar from August 2008 to August 2010. The Vela pulsar is a neutron star, itself spinning at a dizzying 11 times per second and the brightest and most persistent source of gamma rays in the sky, giving an anchoring point for Fermi's own spin.

Hellish coal fires roast underworld for a century

WHEREVER there is coal, there will be fire. For centuries, we have dug up the combustible rock to power our industries, and we continue to rely on it to light our homes and keep the wired world humming. But each year millions of tonnes of coal are burned inadvertently, too - in underground fires that even now rage out of control all over the world.

Nowhere is this on more dramatic display than here in Jharia, in India's Jharkhand state, where underground fires have been burning for nearly a century. Dozens of fires are still active in the coal-rich region, exposing residents to a constant stream of air pollution that can include methane, sulphur and mercury. As the seams smoulder away, the ground above them becomes prone to collapse - taking with them any houses, roads or other infrastructure built on the surface.

China, the world's largest coal-producing nation, has its own vast coal fires. A study published in 2009 by the US Geological Survey estimated that anywhere between 0.5 and 10 per cent of China's coal supply may be on fire. And there are perhaps hundreds more fires going in the US. But numbers remain sketchy - even if the blazes start on the surface, they can quickly migrate underground and stay out of sight for years.

No one knows whether the sum of all the carbon emissions from such fires adds up to anything of consequence for climate change. Researchers who have guessed at the size of the global conflagration suggest it is only a tiny fraction of what we burn in our factories and power plants.