Transcript

The peatbog problem

DR. FRED WORRALL

Our largest store of carbon in the country are not our forests, it's our peat bogs. The peat bogs of the UK store more carbon than the forests of Britain and France combined.

JULIETTE MORRIS

How significant a part can peat bogs play in helping to tackle global warming?

DR. FRED WORRALL

Oh, oh tremendous. The amount of carbon stored in our peat lands in the UK is the equivalent of 21 years of total UK CO2 output. So that's all the CO2 from cars, power stations, everything.

JULIETTE MORRIS

Gosh.

DR. FRED WORRALL

There's 21 years worth. And that's a relatively conservative estimate. So if we damage these areas, we're going to be contributing to our CO2. But also, this stuff has been growing here for thousands of years, and there's no reason why it couldn't keep growing for another 6,000, 8,000 years. This has been growing here since the last ice age, so it can keep on growing. And that means it can keep on storing carbon and keep on taking carbon out of the atmosphere. So if we manage these well, they will actually help us solve our problem. If we manage them badly, they will contribute to our problem.

JULIETTE MORRIS

Keeping across all these carbon movements is Fred's colleague, Bob Baxter.

JULIETTE MORRIS

So how does it work?

DR. BOB BAXTER

Well, what it's got is two major components that you can see here. One is simply just measuring. As air passes through the prongs of the system, the concentration of carbon dioxide in the atmosphere at 10 times per second. So very rapidly. And coupled with that, we have basically wind coming across the landscape, bouncing across the landscape if you like. We need to know the wind speed, so we use something called a sonic anemometer, which are the prongs that you can see on that system there. People at home may recognise the cup anemometer, which you see on weather stations often spinning around, telling wind speed. But that's just in one direction, just in the horizontal. We need to know whether the air is moving up from the land or down to the land.

JULIETTE MORRIS

And that then obviously tells you which direction the carbon's going in.

DR. BOB BAXTER

Yes, exactly.

JULIETTE MORRIS

Ultimately, what's going to happen to all your research?

DR. BOB BAXTER

So, what we're trying to do here at the present time is get a long run of information day by day. Early days at the moment in terms of what is happening certainly, but through modelling, through trying to predict into the future, then we're trying to use this as a baseline information of a number of years trying to predict what is happening in terms of global warming.

DR. VINCENT GAUCI

At the Open University, we're also researching greenhouse gas emissions from carbon-rich wetland ecosystems. Bob Baxter uses a micro meteorological tower to integrate over very large scales. But if you're interested in the very fine scale, like we are, all you need is this. It's called a chamber and it's used to trap emissions from the soil so we can analyse what they are. So you place a chamber on the soil's surface, and here we've got a nice soggy, peaty soil surface, which should be producing lots of methane, and you define the volume of the chamber by placing a lid onto the top there and sealing it. It's simple but effective. With the chamber in place, we can take an initial sample. This should show a composition that is similar to the ambient local atmosphere. It's our baseline sample. And then we wait, taking samples over time. 20 minutes later, I come back and take my third and final sample of the volume. I would expect to see a much larger concentration of methane in the chamber. The samples are analysed in the lab so we can calculate the rate at which methane is being produced and get an idea of what's happening to an important carbon store. This kind of field work looks at methane emissions as they are today. But in the lab, we can travel back in time and that's what Ph.D. student Carl Boardman is doing. Inside these sealed units, Carl has a selection of peat cores from a bog and a fen, two different types of peat land ecosystems that produce methane. The units are linked to gas cylinders so Carl can precisely control the makeup of the air inside. And he's particularly interested in the level of CO2.

CARL BOARDMAN

An experimental CO2 level is approximately half modern day concentration. And now that's significant because approximately a half modern-day concentration is equivalent to what was present 21,000 years ago, which was the last glacial maximum. So what we're trying to do is trying to recreate the CO2 concentration in the atmosphere back them.

DR. VINCENT GAUCI

So the air in Carl's experimental cabinet is the same mix of gases as the air would've been at the height of the last ice age, so we can find out how the availability of CO2 would've effected methane emissions back then. The way he samples and records methane emissions is similar to what I was doing out in the field, but a little more high tech. With the chamber in place, Carl can see a readout of the methane emissions immediately.

CARL BOARDMAN

What we're looking at now is a continuous readout of methane emissions coming from the peat core. On the X-axis, we've got time. On the Y-axis, we've got methane concentration in parts per million. The flat line before 800 seconds is the ambient methane concentration. About 800 seconds is when the chamber was put onto the peat core. When the chamber has been put onto the peat core, what you can see now is a linear increase in methane concentration with time that's coming from the peat core. The main reason why we're doing it is because current research is based upon modern day parameters; so when these studies or these models try to extrapolate and go back in time, they're actually constrained by the fact that they're using these modern day relationships. Well, hopefully, the results that we get from this experiment will constrain the models that are currently out there.

DR. VINCENT GAUCI

So, in a modern lab, like the one where Carl is conducting his experiments, you can really push or manipulate or constrain the system you're investigating to find out how it works. Same thing's happening with earth's climate system, where the carbon balance is being perturbed by human emissions. Now, we can really mimic these cycles and these perturbations in the laboratory, and that really helps us to find out what's going on out there in the real world. The cycle of carbon is the key to life on Earth. Plants absorb carbon as CO2 through photosynthesis, and its re-released over time through decomposition. But the balance of carbon is also important in regulating climate. So, as our climate changes, it becomes more and more important for us to understand both the balance and cycle of carbon. And that will help us to understand what will happen in the future.