Global Warming & Ocean Gas: An Interview with Rice University Professor Gerald Dickens

SupremeMasterTV: We are meeting with Professor Gerald Dickens who is professor of Earth Science at Rice University here in Houston, Texas, USA. It’s a pleasure to have you on the program Professor Dickens and our topic of discussion is ocean gas and the potential effect of global warming on this ocean gas.
Can you tell me firstly, what ocean gas are we talking about?

Professor Dickens: Most of it’s methane, and there will be methane that is stored in the sediments at the bottom of the ocean.

SupremeMasterTV: I understand that it’s stored in a crystal form. Can you explain that?

Professor Dickens: Yes. Methane can be both dissolved in water, it can be as gas bubbles or it can be in an unusual structure, what we call methane hydrate. That’s when we take methane molecules and water molecules and then combine together to form a cage, with the methane on the inside.It looks very much like ice.

SupremeMasterTV: And I understand that it’s called “fire in ice.” Can you explain that?

Professor Dickens: Well, because it looks very much like ice, but as it melts it releases methane, which is the same gas that’s used in natural gas for stoves and things like that.So you can imagine if you put a match to it, it looks like a piece of ice with a flame on top.

SupremeMasterTV: Now the next thing is, are we talking about any other gases particularly in the ocean, or is it mainly methane?

Professor Dickens: Well, there is certainly carbon dioxide that’s dissolved in the ocean and that’s a major role, but we don’t usually think of it as in the gas phase there.  And so really, the main gas that we’re thinking, in terms of the large amounts of gas in the marine system, is methane.

SupremeMasterTV: Can you tell me how is that methane produced in the oceans? How is it actually produced?

Professor Dickens: Most of it occurs when organic carbon lands on the sea floor. That means things, organisms, when they die, as they fall through the water and land to the bottom of the ocean. As they get buried, various microbes start consuming the organic carbon. And one set of microbes is the Archaea, and a sub-set of the Archaea are the ones that produce methane. So they take various constituents from the original organic carbon and convert it to methane.

SupremeMasterTV: Very interesting, and I understand there’s a whole eco-system in these organisms down there on the ocean floor in the sediment.

Professor Dickens: Yes.

SupremeMasterTV: How does the methane stay in the ocean? What is keeping the methane there?

Professor Dickens: This one’s a little bit complicated to explain. Essentially, it’s always there, but it’s always been added to and it’s leaving. So in other words, as the methane’s being produced, it’s also being consumed. So we end up with a steady state system.

Perhaps the best analogy would be a forest. So, with photosynthesis, we make new organic carbon in trees and as the trees die, they release organic carbon.

The same thing happens in marine sediments. So, as the organic carbon enters the sediment, the Archaea turn it into methane. That methane is now in the sediment but, at the same time, it’s slowly leaking out. And as it leaks out, it gets either consumed by oxygen or another species that’s dissolved in water which we call sulfate. So those are our sort of outputs.

SupremeMasterTV: And can you talk about temperature and water pressure in relationship to methane and hydrates of methane.

Professor Dickens: Sure. In this cycle that we’ve just talked about, as we make methane, if a lot of methane is made and we’re at relatively high pressure caused by the water, and at relatively cold temperatures, such as the bottom of the ocean, then, as we start making the methane, it will precipitate out in this solid clathrate phase that we talked about earlier, where the water and the methane combine to form this cage-like ice structure.

And that will precipitate and clog up the pores in the sediment. So you can imagine a little bit of methane going in, a little bit of methane coming out. But most of the methane in many parts of the world,  is  stored in the solid phase in the sediment.

SupremeMasterTV: And whereabouts is it distributed? Whereabouts in the ocean floor do we find this methane?

Professor Dickens: Well, in general we sort of need a couple of places. First we need, to get these very large methane deposits where the methane is in the solid phase, we need both cold temperatures and relatively high pressures. We’re talking generally 500 meters or so water depth.

Professor Dickens: For example, if we go out in the middle of the ocean, we have very cold temperatures at the sea floor. The waters are very deep. But there is very little organic carbon reaching the ocean there.

So we don’t see very much methane. In fact, in the middle of parts of the ocean, there is really no methane. However, as we get closer to the continents, we have both organic carbon coming off rivers, as well as we have fairly productive regions.

So you can imagine where this puts it, is on a sort of slope of continental margins, where we have both the input and supply of organic carbon, plus the pressure, plus the temperature.

SupremeMasterTV:The organic carbon is things like what, decomposing organisms or plants or…?

Professor Dickens: The simplest way for the average person to think of it is, a fish dies and it falls to the bottom. But in terms of overall mass, most of it is phytoplankton. So single celled organisms, algae, diatoms, various phytoplankton that live and die and fall down to the bottom of the ocean.

SupremeMasterTV: Is the methane fairly evenly distributed around the world on these continental slopes, or is there more concentration in various areas of the world?

Professor Dickens: It’s clearly distributed in some places more than others. It’s in particular in areas where we’ve had a lot of organic carbon land on the sea floor for quite some time. None of these systems are new. So they take a long time to accumulate very large amounts of methane, we are talking millions of years. So you need a supply of organic carbon for a long time.

There are certain areas where we’ve had this supply, and those are the areas we really find a lot of methane. It’s a little more complicated than that. Part of it is, there are areas around the world that we haven’t really looked, so we don’t know the full distribution. But I think it’s fair to say that it is unevenly distributed. But, in general, we have found it around all continents.

SupremeMasterTV: What are the beneficial effects of methane? 

Professor Dickens: Well, I guess it depends who’s benefiting. I mean, certainly, for humans, we like to use methane as natural gas. It’s now a large fraction of the energy, in many countries, is derived off natural gas. And certainly, as we talked about before, you can light methane hydrates or the methane that comes off these materials.So it can be used as an energy source. Certainly, it’s part of the large eco-system that we have just scratched the surface. We don’t really understand this. But this very large, what we call the deep biosphere, this methane’s crucial to that eco-system.

SupremeMasterTV: Coming back now, so the fact that the methane stays sequestered in the ocean as long as the temperatures are cold enough and the depth of the ocean, and there’s enough pressure. So what about warming? How does global warming have the potential effect on this methane sequestered in the oceans?

Professor Dickens: We always have a little bit of methane being formed and a little bit of methane leaving in this large body of methane that's sitting there. However, that large body is sensitive to pressure and temperature and so, what we know, at least in the laboratory, is if we take the solid phase and we either increase the temperature or decrease the pressure, that solid phase goes from the ice-like crystal structure into its constituents, so into water plus gas.

And so what we think happens, and it certainly potentially can happen, is as you warm up marine sediment or decrease the pressure, the solid phase can convert to gas and then you have an over-pressured system, and we think that a lot of gas can come out very fast.

SupremeMasterTV: Coming back now, so the fact that the methane stays sequestered in the ocean as long as the temperatures are cold enough and the depth of the ocean, and there’s enough pressure. So what about warming? How does global warming have the potential effect on this methane sequestered in the oceans?

Professor Dickens: We always have a little bit of methane being formed and a little bit of methane leaving in this large body of methane that's sitting there. However, that large body is sensitive to pressure and temperature and so, what we know, at least in the laboratory, is if we take the solid phase and we either increase the temperature

or decrease the pressure, that solid phase goes from the ice-like crystal structure into its constituents, so into water plus gas.And so what we think happens, and it certainly potentially can happen, is as you warm up marine sediment or decrease the pressure, the solid phase can convert to gas and then you have an over-pressured system, and we think that a lot of gas can come out very fast.

SupremeMasterTV: So what would that do to the world? To the plant life, the human life the planet itself, if a lot of methane gas was released as a result of global warming heating up the oceans? What are the potentials?

Prof. Dickens: Well, the first thing to think about is, where does the methane go? So, if the methane comes out of the sediment there's really sort of two possibilities.

One is it would go into the ocean and be oxidized in the ocean, in which case the methane would be converted to carbon dioxide in the ocean. And probably the most significant effect right off the bat, is acidification. So you drop the pH.

SupremeMasterTV: Yeah, the oceans would become acidic, wouldn’t they?

Prof. Dickens: The second possibility is, of course, you could bubble methane up to the atmosphere. Or, it turns out an interesting phenomenon that we have discovered is that sometimes pieces of hydrate will float, and so they can float up very shallow and then dissociate near the ocean surface.

So, there's ways to get methane into the atmosphere.

Now, there, it turns out, what's interesting with methane, is it's a very potent greenhouse gas, much more potent than CO2. So the net effect of that is to essentially contribute to warming.

SupremeMasterTV: So we're talking about volumes here. How much volume of methane? I've read estimates of anything up to 10 trillion tons of methane in the ocean.

Prof. Dickens: Let's just think about this. I usually think in gigatons and so a gigaton is 1 trillion tons.

SupremeMasterTV: 1 trillion tons.

Prof. Dickens: And so we usually think somewhere on the order of 2,000 to 20,000 gigatons are the sort of estimates for how much methane is stored in the crystal phase, of which again there will be also gas bubbles and dissolved. And so the total system,

we're talking on the order of somewhere on that range of 2,000 to 20,000 gigatons of methane.

SupremeMasterTV: And if that was released into the atmosphere?

Prof. Dickens: Well, I don't think it would be ever possible to release it all, but even if a fraction of thathttp://suprememastertv.tvhttp://suprememastertv.tv We can think about, for example, what humans are doing today. So probably, you know, if we burned all the fossil fuels that are available today, somewhere on the order of 4,000 gigatons of carbon that will be added to the atmosphere.

So you can imagine that if 10,000 gigatons of methane - an average number for estimates that people have made…If one-tenth of that goes, you know, we are on the order of magnitude of what we are doing today, in terms of adding carbon dioxide.

SupremeMasterTV: So is methane toxic to humans?

Prof. Dickens: Certainly, if the entire atmosphere around you is methane, it is toxic.

SupremeMasterTV: There's no oxygen to breathe.

Prof. Dickens: But small amounts of methane are not going to be toxic, but certainly it's flammable so it's not a good idea to have lots of methane.

SupremeMasterTV: Has this ever happened in the past, where a lot of methane gas has been released into the atmosphere on Earth?

Prof. Dickens: We think so. We are very confident that there are times in the past where large amounts of carbon dioxide go into the ocean and / or atmosphere very quickly. We think that the source of that carbon dioxide is oxidized methane. So that methane has come into the system and either by mixing with oxygen in the ocean or through various reactions in the atmosphere, it converted to CO2.

SupremeMasterTV: And when did this happen?

Prof. Dickens: Probably the best studied of these times is about 55 million years ago, right after the Paleocene-Eocene boundary. And it's an interesting time, in that we see all sorts of environmental consequences. So something clearly happened.

In fact, that's why we have a boundary there, because the organisms on life changed quite dramatically across this time period. And we see things such as over 6, 7 degree warming around the world, including the high latitudes. We see changes in the hydrologic cycle, so some places become very dry, some places become very wet. We see ocean acidification. We see changes in oxygen content in the ocean. So many, many different environmental changes occurred during this time.

SupremeMasterTV: Has this ever happened in the past, where a lot of methane gas has
been released into the atmosphere on Earth?

Prof. Dickens: We think so. We are very confident that there are times in the past where large amounts of carbon dioxide go into the ocean and / or atmosphere very quickly. We think that the source of that carbon dioxide is oxidized methane.

So that methane has come into the system and either by mixing with oxygen in the ocean or through various reactions in the atmosphere, it converted to CO2.

SupremeMasterTV: And when did this happen?

Prof. Dickens: Probably the best studied of these times is about 55 million years ago, right after the Paleocene-Eocene boundary. And it's an interesting time, in that we see all sorts of environmental consequences. So something clearly happened. In fact, that's why we have a boundary there, because the organisms on life changed quite dramatically across this time period.

And we see things such as over 6, 7 degree warming around the world, including the high latitudes. We see changes in the hydrologic cycle, so some places become very dry, some places become very wet. We see ocean acidification. We see changes in oxygen content in the ocean. So many, many different environmental changes occurred during this time.

SupremeMasterTV: What happened to the animal life then? What happened to the plant life? Is there evidence what happened to them?

Prof. Dickens: Well, it’s interesting. So if you look at organisms in the bottom of the ocean, many of them seem to go extinct. So life was not too good at the bottom of the ocean. On land, it's a much different sort of response and, you know, looks like organisms migrate. And so we see just the distribution of organisms change very, very fast.

Prof. Dickens: If we go into the north pole and drill a hole there and collect the sediment that was deposited there 55 million years ago, it looks like temperatures somewhere in the 70 degrees, although we're not totally sure whether those are summer temperatures or annual temperatures. Nonetheless it's still quite warm.

SupremeMasterTV: Very interesting. And we are thinking that methane was probably the reason at that time, is that right?

Prof. Dickens: Somehow… we think that methane is some component of this. And what we're not sure is whether it's essentially the trigger or a feedback.

SupremeMasterTV: We were talking also about what can we do to help with global warming?

Prof. Dickens: As far as methane, in terms of global warming, probably, certainly over the next 100 or 200 years these methane reservoirs in the deep ocean are probably not responsive at that sort of time scale. On the other hand, if we go to up to permafrost regions, yes, we can get methane coming out from the permafrost, which may act as a feedback.

So as we start melting permafrost we release extra methane As far global warming, that is just a huge problem. I can give you my own personal opinions. I think it’s going to take a radical view of a change in lifestyle, as well as new technologies. And it’s really going to take a combination of both.

There are all sorts of these feedbacks, and many of them we don’t really fully understand. So, for example, there’s a paper, just a couple weeks ago, summarizing recent evidence that as you start warming things up, the biosphere, the plants start releasing more carbon than they take in.

So when you start doing things, they start taking in carbon, but then they start kicking it back out. So it’s like, gosh! That’s a feedback that’s really problematic. That’s not in our models. And there are many of these things that we just really don’t understand right now.

SupremeMasterTV: I remember, in reading the papers, you were saying that the carbon in the methane is actually like a huge capacitor that people haven’t really worked into their thinking, and to do with the carbon cycle.

Prof. Dickens: The carbon cycle. If you think of three boxes, it’s the easiest way to think of the carbon cycle. You have an atmosphere, a biosphere and the ocean.

Prof. Dickens: Biosphere, trees, plants; so the terrestrial biosphere. And all of these
are connected. So you think of three boxes, much like, I like to think of it as a swimming pool and 2 hot tubs. And so between each one of these boxes there are inputs and outputs. In the analogy between the swimming pool and the hot tub, it’s essentially the ocean is the big box. And it’s a common misconception for the average person, they think that all the carbon is in trees.
 
But it turns out that most of the carbon, about 93% of it, is in the ocean, not in trees or in the atmosphere. So what’s happening right now is we’re adding a lot of carbon to the atmosphere. It’s coming in much faster than it can go into the biosphere or into the ocean. So that’s why the CO2 is going up very, very quickly.But it turns out, that if you suddenly realize there is a lot of methane on the planet, somewhere there is now a 4th box.

So you can’t have an ocean that’s nominally 35,000 gigatons and then suddenly talk about methane being 10 or 20,000 gigatons. There’s another box in the system. So the simplest way to think about it is a capacitor. You have organic carbon. The normal way people think of the carbon cycle is, you have a little bit of carbon coming into the system, through volcanoes or through weathering, and a little bit of carbon coming out of the system. So you have this large box, a little bit of input and a little bit of output and the carbon cycle in between all this. And then, essentially by adding methane, what you have to say is, some portion of the organic carbon leaving the system then gets converted to methane, so you add a new box. Then a little bit leaks out and it goes back into the ocean.

The idea for the capacitor is that output can change dramatically in the time frame. Sometimes we can have a lot of methane come out very quickly.

SupremeMasterTV: With the temperature change.

Prof. Dickens: With the temperature change.

SupremeMasterTV: And the pressure change.

Prof. Dickens: Yeah.

SupremeMasterTV: Is there any other comments, anything else that you think the general public should know?

Prof. Dickens: The fantastic thing is, I think I mentioned to you earlier today, is that 15 years ago, I don’t think anyone would have even asked me. I just sort of did my own thing and studied methane and climate change. Now people are actually interested.

SupremeMasterTV: That’s a very important topic, very important. Well it’s been an absolute pleasure having you on the program, Professor Dickens. Thank you so very much for granting us this interview.

Prof. Dickens: Well thank you for having me.