How and why does a scientist like me study the gas methane? The 'why' part of the question is often easier to answer than the 'how' part so I'll answer that first.

Methane, like carbon dioxide, is an important greenhouse gas but it differs from the more widely reported CO₂ in a couple of important ways.

Firstly, methane is more powerful at trapping the suns rays. As a greenhouse gas it is actually more than 20 times as powerful as CO₂.

Vince collecting samples.

[photo © copyright Vince Gauci]

The second important difference relates to its lifetime in the atmosphere: methane lasts around 10 years in the atmosphere where as CO₂ can stay in the atmosphere more than 10 times as long.

The relatively short lifetime of methane means that atmospheric concentrations of the gas, and therefore its contribution to the greenhouse effect, is sensitive to short-term changes in sources and sinks of the gas. These sources include natural wetlands, rice paddies, land fill and cow burps.

The other key reason for studying methane is that over the past century, the concentration of the gas has been increasing - although in the past decade the pace of this change has been decreasing and, until a very recent rise was reported, had almost halted.

The reasons behind this pattern of growth are important to understand so that we can improve predictions of climate into the future.

Collecting methane samples in Flitwick.

[photo © copyright Vince Gauci]

I am interested in the controls on the emission of methane from the largest individual source: wetlands. Natural and artificial wetland ecosystems such at peat bogs and rice paddies produce methane as a consequence of anaerobic decomposition in saturated soils.

My work chiefly deals with chemical controls over the production of methane in these ecosystems and pathways the gas takes in making the transition from the soil to the atmosphere. Much of my work has examined the effect of sulfur pollution in acid rain on the emission of methane from wetlands and rice paddies.

This is important because methane emitting wetland areas receive sulfur pollution via long-range transport of pollution. They also get sulfur from a natural form of pollution – volcanic eruptions.

The sulfate component of acid rain pollution is thought to stimulate one set of microbes that then out-compete methane-producing microbes for food. The result is a reduction in methane emission, and this seems to be sufficient to offset the growth in wetland methane emissions that would be expected to result from global warming.

We've also investigated the effects of a large Icelandic volcanic eruption that deposited sulfate over a wide area of the northern hemisphere in 1783 and 1784 and found that changes in atmospheric methane concentration at the time, as recorded in ice-cores, are consistent with our understanding of how sulfur pollution affects the wetland methane source.

My other interest is in novel pathways for anaerobically produced methane to leave saturated soils and get into the atmosphere. Until recently, methane was thought to leave soils through diffusion, bubbling or through the hollow vessels of wetland adapted herbaceous plants like sedges and rushes.

In recent studies we've found that wetland trees contain some of the same adaptations as sedges that enable them to survive in sodden soils and this enables mature trees to emit methane from their trunks – an important finding given that many of Earth's wetlands are forested.

Together with a team of PhD students, we shall be going to the Kalimantan peat swamp forests of Borneo in early 2009 to investigate whether tropical wetland trees in Borneo are also functioning in the same way.

Find out more

Stephen Self explains why the 1783 Icelandic eruptions affected the whole of Europe.

Discover the routes into studying science with the Open University.

Explore more Open University research with BBC Radio 4's The Material World.

About the author

Vince Gauci was appointed Open University lecturer in Earth Systems and Ecosystem Science in November 2004. He is a member of the Department of Earth and Environmental Science Biogeochemistry group, which in turn is part of the cross departmental and cross faculty Ecosystems Research Group.
Browse a list of Vince Gauci's published research.

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Three o’clock Sunday afternoon, we leave Milton Keynes with the car loaded up with equipment.

"We" are John Zarnecki, Professor of Space Science, and Karl Atkinson, PhD student, both from the OU’s Planetary and Space Sciences Research Institute.

"The equipment" is an aluminium contraption about two and a half metres high, of tripod shape with a horizontal arm that can drop a sensor from various heights.

We are off to Chesil Beach, on the coast of Dorset. Why are two planetary scientists going to the Dorset coast?

Obviously, because Chesil Beach is like the surface of Titan, Saturn’s largest moon!

The drop rig at Chesil beach on an earlier (sunny!) trip.

Let’s explain. On January 14, 2005, the European Space Agency’s Huygens probe landed on the surface of Titan after a seven and a quarter year, three and a half billion kilometre journey.

The first part of the probe to strike the surface was a penetrometer, part of the Surface Science Package (SSP). SSP was one of the 6 scientific instruments carried by Huygens. For about 12 milli-seconds (12/1000th of a second), the penetrometer - essentially an instrument "stick" about 10 cm long - was the only part of the Huygens Probe which was in contact with the surface, as the rest of the probe floated down to the surface under its parachute.

At the point the approximately 300 kg probe struck the surface, and from that time on, the penetrometer signal (essentially a measurement of force against time), becomes nearly impossible to interpret. But the brief ‘clean’ signal can give a clue as to the nature of Titan’s previously unseen surface.

Karl Atkinson had started his PhD at the Open University just a few months before Huygens arrival at Titan. He had been given the task of preparing for the receipt of this precious signal (before we could even be sure that the probe would survive the perilous descent and landing).

He collected a range of reference material signatures – including those of various sands, gravels, clays and some more exotic materials. The purpose was to represent, in terms of mechanical properties for example, the range of surfaces which had been predicted for Titan. Remember that Titan is basically an icy body that was predicted to be possibly covered by a layer of organic sludge, or even lakes or seas of liquid methane.

The surface of Titan imaged by the Huygens probe.

[image © copyright ESA/NASA/JPL/University of Arizona]

When January 14 came and went, Huygens behaved almost immaculately – and the penetrometer collected its precious data. The on-board camera showed that Huygens had landed on what looked like the shore of a dried-up lake bed. Some "pebbles" were visible sitting on top of a surface which could not be fully resolved by the camera. So what was it?

This was the question faced by Karl for his PhD project. His basic interpretation was that the penetrometer, after at first producing a brief high force signature had pushed into a soft surface. From his work in the laboratory, it seemed that the material on Titan was probably granular or grainy. Could it be Titan’s version of sand or gravel, produced by the continued action of flowing liquid over the underlying bedrock - which, in the case of Titan, would be methane flowing over ice?

He produced many sample surfaces in the laboratory but knew that natural processes on Earth would be better at producing some realistic ‘targets’ for Titan. For example, the roughly 18 mile-long Chesil Beach offers a whole range of different local granular environments – from well-sorted cobbles through to coarse sand.

Furthermore, regions were found where the beach had distinctive layers lying on top of each other that could be seen in the penetrometry signature. Of course, Titan’s surface material is ‘icy’ rather than ‘rocky’ but ice at -179^oC has similar mechanical properties to rocky material on Earth’s surface.

So, in the early part of 2008, a programme of simulated impacts into the range of surfaces offered by Chesil Beach was carried out. But life is never simple. Some of the data was unexpected and needed to be double-checked.

So, on 20th October 2008, we found ourselves on the beach to carry out a selection of "simulated drops" close to the actual impact speed on Titan, 4.6 metres per second. These tests were done in the face of a raging gale -inhospitable, but not quite as bad as Titan itself!

Using the beach drops and previous results from laboratory work, an estimate of the material grain size at each site was made and compared with the actual sizes observed. Accounting for the difference in density between the sand on the beach and the presumed water ice on Titan’s surface, this work suggests that the grains at the Huygens landing site are similar in size to coarse sand such as that found at the western end of Chesil beach.

Furthermore, in several signatures we were able to determine the depth and thickness of distinct layers and material grading (grains being sorted with depth) caused by wave action on the beach surface. These features however are not seen in the Titan signature.

Flight data returned by the penetrometer from the surface of Titan, showing time in milliseconds against force in Newtons.

This all helps to build up the picture of what we think the surface of Titan is like and may help understand the physical processes at the landing site. Remember that these data from Huygens won’t be improved on for at least 20 years - when we hope to return to Titan with an even more ambitious mission.

Find out more

Stardate: Mission To Titan - our space series reported on the mission
Mission to Brighton - finding penetrometers impenterable? Try our interactive explanation.

It had been one of those research trips where everything was going wrong. We were four weeks into a five week field trip to Mount Etna and we had not finished the levelling, dry tilt or GPS measurements. We'd lost precious time with three weeks of ice and early snowfalls that made work at the summit impossible, and our trusty, 17-year old digital level had let us down. The manufacturer had been good enough to send us a replacement, but that took a stressful five days, and to cap it all Etna had decided she would send a lava flow to destroy one of our treasured stations that I had installed 21 years ago.

The last thing I wanted to do was spend a day being nice and polite to the BBC.

Studying Mount Etna.

On the day of the BBC's arrival the weather was perfect. Their plane was to land in the afternoon, but with things as they were we couldn't waste the opportunity, so at first light we set off for the summit of Etna.

Andy Bell, a seismologist from Edinburgh, was leaving us the following morning, so it was our last day with five people, and thus our last chance to measure the critical stations in the Valle del Bove.

This was a borderline-dangerous escapade down into a vast cauldron five kilometres wide and one kilometre deep, that, for the previous five months, had been filling up with flow after flow of loose Aa lava: red-hot piles of loose unstable stones sharp as glass.

On a good day this would have taken a solid eight hours of hard slog, but this was not a good day.

The new lava had made the task almost impossible, so after ten hours we were still floundering around in pitch darkness, out of radio and mobile phone contact, with the streams of lava glowing behind us in the darkness.

When at last we limped bruised and bleeding over the lip of the valley, Material World producer Martin Redfern's voice over the phone was a paradigm of polite restraint. "Delighted to make contact…" etc, etc.

The Material World team get an interview.

Not only had we not been there to meet them, and uncontactable to boot, but it transpired that I had given them the wrong website for their Bed-&-Breakfast, so instead of being round the corner from us in Nicolosi, the highest village on the volcano, they were 20 miles away in Adrano, at the foot of the mountain. Oh dear, oh dear, oh dear, and a lot of swearing…

The following morning was a different kettle of fish. We were scarcely half an hour late when we finally met Martin and presenter Quentin Cooper at the Sapienza halfway up the south side, from where we began the slow ascent up the vehicle track to the top, with six of us crammed into our 4x4, together with seven GPS kits, tripods and rucksacks.

The nature of the work, and the difficult and sometimes dangerous conditions, means that at least 4 people (2 teams of 2) are required. This year there is Saskia van Manen, a Dutch PhD student at the Open University, Melanie Zacheis, completing her Masters at Portsmouth University, and Kate Gladstein from Vermont University, U.S.A., whose work here on Etna will form part of an undergraduate project.

Etna does not always erupt its lava from the summit craters. Now and again a new fissure opens in the side of the mountain, and this had happened in May, and the lava was still sluggishly oozing out. Before the main business of the day, we took an hour's scramble to look at how the eruption was progressing.

It's wise to keep a gas mask to hand.

We were able to stand on the edge of the erupting fissure, with acrid sulphur dioxide and hydrogen sulphide pouring from the abyss, but there was total silence, and no sign of flowing lava. Only when the mist cleared could we see the bluish gas and the deep red of the active flows far below us in the Valle del Bove. Between us and the flows the lava was travelling through a series of underground channels.

Our work concentrates on measuring with extremely precise instruments how the volcano changes shape from year to year, as the magma forces its way from deep within the volcano to the surface, and as portions of the volcano slide downhill or jostle in response to shifting gravitational or tectonic forces. I have been doing this once to three times a year since 1975, and this year we have already found some exciting results.

Not only has much of the land on this eastern side shifted more than one metre towards the sea, but there has also clearly been an injection of magma down the north side of the volcano, deep beneath the surface.

We measure vertical movements and ground tilt of more than 300 stations over the summit and flanks of this huge volcano with a precise level - now old and venerable technology, but still twenty times more accurate than any other method of height measurement.

However with six of us in the vehicle we have had to leave this equipment behind. Today we would be using dual-frequency GPS, capable of measuring our 100 stations to an accuracy of a few millimetres over distances of tens of km. Up to seven GPS kits are set up at stations all over the mountain at the same time, and left running for between 20 minutes and ten hours.

As the recording got under way, it became clear that this is to be at least partly a fly-on-the-wall affair, with the odd more structured interview.

We approached the first GPS station, the microphone was switched on, but as the girls began to set up the equipment a thought crossed my mind, and I nipped across to obstruct the view of the handset, but too late.

Quentin opened with "I can't help noticing that the name of this station is 'Clenched Buttock'…". Oh dear, oh dear, hope they cut that bit out.

Students have been naming these stations now for nearly 40 years, and they range from the poetic to the nostalgic to the comic to the downright rude, but they were all topical at the time and all have a story to tell, and bring back more than anything the flavour of trips long past: Crack of Doom, Eleanore's dream, Cat's Paw, Desolation, Lightning Ridge, Big Girl's Blouse, Defenestration, Sellotaped Egg, Monkey Boy, Chocky's Hill, and the greatly-regretted Rosanna, now buried deep beneath the accumulating lavas of the 2008 eruption.

We quickly got used to the microphone, even forgot it was there. All in all things seemed to go well, though I was aware of making the occasional gaff. There were countless interviews with me and each of the women, but I still felt we were only scratching the surface, and that only a small part of our work, and of the multi-faceted nature of Mt Etna and its eruptions, was being recorded.

At the end of the day we made the ascent to the edge of two of the four summit craters.

An otherworldly vista.

Normally one can hear explosions or at least puffs of gas deep down inside, but there was still total silence, so Radio 4 listeners will have to be content with descriptions of the yellow sulphurous deposits and our coughing fits as the wind takes the gas in our direction now and again.

The BBC's visit marked a turning point in the trip. After they had gone, the weather changed to its normal calm, sunny, autumnal best, and in the final few days we managed to get everything completed.

Take it further

The Material World from BBC Radio 4 and The Open University

The BBC's Martin Redfern reported on this trip for From Our Own Correspondent
Listen to Martin's report

Discover the science behind volcanic eruptions

How was the entire continent affected by the 1783 Laki eruption on Iceland?

Explore volcanoes on the surface of Venus

Study science with the Open University

About the author

John Murray has been working for nearly 40 years studying the active volcanoes of Mount Etna. He commenced a long-term study in 1975, the longest continuous study of an active volcano conducted by an individual. John predicted the 1983 eruption a year before it happened. He joined The Open University in 1989, working on planetary science and volcanoes.

View John’s recent research publications by visiting John's entry in Open Research Online – a collection of The Open University’s published research.

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