It was no secret that deep-sea hydrothermal vents were occupied by numerous exotic species, but when geochemist Erwin Suess arrived at the Geomar Centre from Oregon State University in 1989, he told of stranger things – cold seeps surrounded by oases of life, mysterious sources of chemical energy rising from inside the Earth, and vast deposits of a substance that until then had been dismissed as an intriguing but insignificant by-product of natural processes: methane hydrate.
It was time for the geosciences to break out of the seclusion in which they, like most other scientific disciplines, had worked. Now they tried to make themselves heard. They hoped to develop methods for predicting and averting natural disasters and long-term changes to the environment and climate. Methane seemed the answer to the energy problem of the future. The media sensed a story, and the geoscientists learned gradually how to make use of the new-found interest in their work.
None of this seemed to have come to the attention of the man steering Johanson's taxi towards the Firth of Kiel. For the past twenty minutes he had been venting his frustration at the idea of a research centre that had cost millions of euros being entrusted to a team of scientists who took off on cruises round the world while he could barely make ends meet. Johanson spoke excellent German, but felt no desire to set the record straight. Besides, he couldn't get a word in edgeways – the driver was talking and gesticulating wildly as the taxi veered from side to side. 'God knows what they get up to in there,' he grumbled 'Are you a reporter?' he asked, when Johanson failed to respond.
'A biologist.'
The driver took that as a signal to launch into a tirade about food-safety scandals, for which he seemed to hold Johanson personally responsible.
'A biologist? So what, in your expert opinion, is safe for us to eat? Because I'm damned if I know! We must be mad to eat the stuff they sell us.'
'You'd starve if you didn't,' said Johanson.
'If I don't eat, I'll starve, and if I do, the food'll finish me off.'
'If you don't mind me saying so, I'd rather die from a toxic steak than be crashed to death on the bonnet of that tanker.'
Without a flicker of concern the driver spun the wheel and crossed three lanes to take the next exit. The tanker thundered past. Now they were speeding along the eastern shore of the firth. On the opposite bank, giant cranes reached into the sky.
The driver had evidently taken offence at Johanson's last comment: he didn't say another word. They drove in silence along suburban streets past tall, gabled houses until a long row of linked buildings appeared ahead. The complex of steel, brick and glass looked out of place in its domestic surroundings. The driver took a sharp right and screeched to a halt in front of the Geomar Centre. The engine juddered and stopped. Johanson took a deep breath, paid, and got out. The ride in the Statoil helicopter had been a breeze compared to the last fifteen minutes.
'God knows what they're doing in there,' said the driver, apparently to his steering-wheel.
Johanson bent down to the open passenger door. 'Do you really want to know?'
'Sure.'
'They're trying to save the taxi-driving industry.'
The driver gazed at him blankly. 'It's not as though we get many fares out here,' he said doubtfully.
'No, but when you do, you need your vehicle. Which means that when the world runs out of petrol, you'll either have to scrap it – or use another fuel. And that fuel, methane, is at the bottom of the ocean. They're looking for a way to convert it.'
The driver frowned. Then he said, 'You know what the problem is? They never bother to tell you.'
'It's all over the papers.'
'Not the ones I read, mate.'
Johanson nodded and closed the door.
'Dr Johanson.' A tanned young man had emerged from a round glass building and was heading towards him.
Johanson shook his outstretched hand. 'Gerhard Bohrmann?'
'Heiko Sahling, marine biologist. Dr Bohrmann's giving a lecture. We could listen, if you like, or grab a coffee in the canteen.'
'Which would you rather?'
'Entirely up to you. Interesting worms you sent us, by the way.'
'You've been working on them?'
'We've all been working on them. Tell you what, why don't you come this way? We'll save the coffee for later. Gerhard will be finished in a moment, and he won't mind if we eavesdrop.'
They entered a spacious foyer with an air of sophisticated functionality about it. Sahling led him up some stairs and across a steel suspension bridge. For a serious research institute, thought Johanson, the Geomar Centre was suspiciously trendy.
'We usually use the auditorium for lectures,' explained Sahling, 'but today we've got a class of schoolkids.'
'How terribly worthy.'
Sahling grinned. 'To a bunch of fifteen-year-olds, an auditorium is just another classroom, which is why we do a tour with them instead. They can look at whatever they want – and touch nearly everything – too. We saved the lithotbek until last. It's where we keep our samples. Now Gerhard is telling them their bedtime story.'
'About what?'
'Methane hydrates.'
Sahling slid open the metal door. The raised platform continued on the other side. They took a few steps along it. The storeroom was at least as big as a medium-sized aircraft hangar and led out on to the quay, where Johanson caught a glimpse of a relatively large boat. Crates and equipment were piled against the walls.
'We mostly collect sediment cores and pore-water,' explained Sahling. 'It's an archive of geological history and we're proud of it.'
He raised his hand briefly. Below, a tall man returned the greeting, then focused on the group of teenagers clustered around him.
'It was one of the most exciting things we've ever seen,' Gerhard Bohrmann was saying. 'The grab sampler returned from a depth of nearly eight hundred metres, carrying several hundred pounds of sediment, interspersed with white lumps. We watched as it emptied them on to the deck. Not all of the substance survived the journey.'
'That was in the Pacific,' murmured Sahling, 'in 1996 on the RV Sonne, a hundred or so kilometres off the coast of Oregon.'
'There wasn't a moment to lose. Methane hydrate is highly unstable,' continued Bohrmann. 'I don't suppose any of you will have heard much about it, so I'll try to explain without boring you senseless. Let's imagine the ocean seabed. There's a lot going on down there, but we're going to focus on gas. Biogenic methane, for example, forms over millions of years when plants and animals decay. Large amounts of carbon are released as algae, fish and plankton decompose. Bacteria play a central role in that. One of the key things to remember, though, is that the temperature on the ocean floor is very low, but the pressure's very high. For every ten metres you descend through the water, you gain another bar of pressure. With breathing apparatus you can get to fifty metres, or maybe even seventy, but that's about the limit. The record is a hundred and forty, but I wouldn't recommend it – almost everyone who tries it ends up dead. In any case, we're talking about depths in excess of five hundred metres, and that changes the physics completely. So, when high concentrations of methane seep through the seabed something extraordinary happens: the gas combines with cold water and forms ice. They call it "methane ice" in the papers, but that's not entirely accurate. It's not the methane that freezes, but the seawater around it. Groups of water molecules solidify, forming cage-like structures around each methane molecule. Vast amounts of gas are compressed within the tiniest spaces.'
A schoolkid stuck up his hand. 'Five hundred metres isn't exactly deep, is it?' he said. 'Jacques Piccard went down eleven thousand metres in his bathyscaphe. Now, that's really deep. Why didn't he see ice down there?'
'So you know the story of the deepest manned dive. Very good. But how would you explain it?'
The teenager thought for a moment, then shrugged.
'Well, it's obvious, really,' said one of the girls. 'There's not enough life down there. Once you get below a thousand metres not much d
ecays, so there's hardly any methane.'
'I knew it,' muttered Johanson from his vantage-point on the bridge. 'Women are simply more intelligent.'
Bohrmann smiled at her. 'That's right. Although, as always, there are exceptions. Methane hydrates can also be found in deeper water, even at depths of three thousand metres, if enough sediment containing organic matter is washed down there. It sometimes happens in marginal seas. As a matter of fact, we've also found methane hydrates in very shallow water, where there isn't much pressure. But as long as the temperature is low enough, hydrates will form – on the polar shelf, for example.' He turned back to the rest of the group. 'The main deposits of methane hydrates – compressed methane – are on the continental slopes at depths of between five hundred and a thousand metres. One of our recent expeditions took us to an underwater ridge just off the American coast. It was five hundred metres high and twenty-five kilometres long, and made mainly of hydrates. Some was buried deep within the rock, but the rest lay exposed on the seabed. Since then we've found out that the oceans are full of it, but another important discovery's been made: methane hydrates are the only thing holding the continental slopes together. They act like cement. If you took away the hydrates, the slopes would look like Swiss cheese. Without the hydrates, there'd be landslides.' Bohrmann paused to let his words sink in. 'But there's more to it than that. Like I said, methane hydrates are only stable in conditions of low temperature and high pressure. So, you see, not all the gas compresses, just the top layer. Under the Earth's crust the temperature increases, leaving pockets of methane deep in the sediment that never freeze. The methane stays in a gaseous state, with the frozen layer of hydrate acting like a lid to trap it.'
'I read about that,' said the girl. 'Aren't the Japanese trying to extract the methane?'
Johanson smiled. There was always one kid in every class who was exceptionally well prepared and knew most of the lesson before it had begun. He guessed she wasn't too popular with her peers.
'Oh, it's not just the Japanese,' said Bohrmann. "The whole world would like to extract it. But it's not that simple. When we were collecting our samples from a depth of eight hundred metres, the hydrates started to dissociate when they were half-way to the surface. By the time we had them on board, there was only a fraction of what we'd extracted. Methane hydrates are incredibly unstable. A temperature increase of just one degree at a depth of five hundred metres might be enough to destabilise the entire stock stored at that level. We knew we had to act quickly. We grabbed the lumps of hydrate and plunged them into liquid nitrogen to stop them dissociating. Come and have a look over here.'
'He's got a knack for this,' said Johanson, as Bohrmann led the class to a shelving unit made of stainless-steel frames. Containers of various sizes were stacked inside, with four tank-like, silvery barrels at the bottom. Bohrmann dragged one out, slipped on a pair of gloves and opened the lid. There was a hissing noise and vapour rose from inside. A few kids shrank away.
'It's only nitrogen.' Bohrmann reached down into the container and pulled out a fist-sized lump of something that looked like muddy ice. Within a few seconds it was fizzing and cracking. He beckoned to the girl, then broke off a chunk and held it out to her. 'It's pretty cold, but it won't hurt you,' he said.
'It stinks,' she exclaimed.
Some of the others laughed.
'Yep, like rotten eggs. It's the smell of gas dispersing.' He broke off more chunks and handed them round. 'The dark threads in the ice are seams of sediment. In a few seconds there'll be nothing left but a few specks of dirt and a puddle of water. The ice melts and the molecules of methane are released from their cages to escape into the air. Or, to put that in context, an apparently stable piece of seabed disintegrates, leaving almost nothing behind. That was what I wanted to show you.'
The kids' attention was on the fizzing ice. Bohrmann waited until it had melted, then continued: 'Now, while you were watching, something else happened invisibly. It's why we respect hydrates as much as we do. Remember I said that the methane was compressed by the ice crystals? Well, from every cubic centimetre of the hydrate that you were clutching, a hundred and sixty-four cubic centimetres of methane escaped into the air. During dissociation, the volume of methane increases by a factor of a hundred and sixty-four in the blink of an eye – leaving you with just a puddle in your hand. Taste it, if you like,' he said to the girl, 'and tell us what you think.'
She gazed at him in horror. 'But it smells!'
'Not any more. The gas has dispersed. But if you're worried about it, I'll do it.'
The girl lowered her head towards her hand and licked 'Normal water!'
'That's right. When seawater freezes, the salt separates out. On that basis, the Antarctic is the largest reservoir of fresh water on the planet. Icebergs are made of fresh water.' Bohrmann closed the tank of liquid nitrogen and pushed it back into the unit.
'The idea of exploiting methane hydrates is hugely controversial, and you've just seen why. Suppose we were to destabilise the hydrates? We might set off a chain reaction. Imagine what would happen if the substance cementing the seabed suddenly evaporated. Think how it would affect our climate if methane from the deep sea escaped into the air. Methane is a greenhouse gas. It could heat up the atmosphere, which in turn would warm the seas, which would trigger the breakdown of hydrates, and so on. That's the kind of problem that keeps me and the other scientists here busy.'
'Why bother to extract it in the first place?' asked one of the boys. 'Why not leave it down there?'
'Because it could solve all our energy problems,' the girl chimed in. She pushed to the front of the group. 'That's what it said in the stuff about the Japanese. They don't have natural fuels of their own so they're forced to import them. Methane would solve the problem.'
'That's stupid' said the other kid. 'If something causes more problems than it solves, it doesn't solve anything.'
Johanson grinned.
'You both have a point.' Bohrmann raised his hands in a conciliatory gesture. 'Methane hydrates could solve our energy problems, and that alone is enough to ensure that it's not a purely scientific question. The energy industry has a big interest in hydrates research. According to our estimates, marine gas hydrates contain twice as much burnable methane as all the other known deposits of gas, oil and coal combined. Just take the hydrate ridge off the coast of America. OK, so it extends over twenty-six thousand square kilometres, but there are thirty-five gigatons of hydrate in there. That's equivalent to one hundred times the amount of natural gas used in the whole of America in a year.'
'Sounds impressive,' Johanson whispered to Sahling. I'd no idea there was so much.'
'There's far more than that. I can never remember the figures, but Gerhard could tell you exactly.'
Bohrmann continued as if on cue: 'We can't know for sure, but we think over ten thousand gigatons of methane may be trapped in marine gas hydrates. And then you've got the onshore hydrates under the permafrost in Alaska and Siberia. To give you an idea of the quantities in question, all the available reserves of coal, oil and gas come to barely five thousand gigatons – less than half the amount of methane stored within the hydrates. No wonder the energy industry would give anything to know how to extract it. Just one per cent of that methane would double the United States' fuel reserves in an instant – and fuel consumption there is far higher than anywhere else in the world. Unfortunately it's the usual story. From the perspective of the energy industry, hydrates are an enormous reserve of untapped fuel; but scientists see them as a time bomb. The only option is for both sides to work together- in the interest of mankind, of course. Well, that brings us to the end of our tour. Thanks for coming.' He smiled to himself 'And for listening, of course.'
'Not to mention understanding,' Johanson murmured.
'Well,' said Sahling, 'we hope so.'
'I PICTURED YOU DIFFERENTLY,' said Johanson. He and Bohrmann shook hands. 'On your web page you've got a moustache.'
'I shaved it
off,' Bohrmann fingered his upper lip. 'Your fault.'
'How come?'
'It happened this morning. I was shaving and thinking about your worm, when suddenly I could picture it clearly, wriggling across the mirror in front of me, swinging its tail in a loop. Too bad that my hand and the razor followed. I chopped off a corner and had to sacrifice the rest to science.'
'So now I've got a moustache on my conscience.' Johanson was amused.
'Oh, don't worry – it'll grow back in no time when the next trip starts. On the RV we all sprout beards. The lab's this way. Or would you like some coffee first?'
'No, thanks. I'm dying to see what you've got. So, you're off on another expedition?'
'In the autumn.' Bohrmann led them along glass corridors. 'We'll be heading for the cold seeps in the Aleutian subduction zone. You were lucky to catch me in Kiel. I got back from the Antarctic two weeks ago, after nearly eight months at sea. The day after we docked, I got your call.'
'What kept you there for so long?'
'Delivering over-winterers.'
'Over-winterers?'
Bohrmann laughed.
'Over-winter scientists and technicians. They started work at the station in December. They're extracting ice cores from a depth of four hundred and fifty metres. Unbelievable, isn't it? Ice as old as that can tell us the history of our climate over the last seven thousand years.'
Johanson was reminded of the taxi driver. 'Most people wouldn't be impressed,' he said. 'As far as they're concerned, climate history won't help eliminate world poverty or win the next world cup.'
'We're partly to blame for that, though. Science tends to keep itself to itself.'
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