Antarctic Atmospheric Science
Antarctica is part of the world most affected by a changing climate. Atmospheric research there can help us understand global systems and we spoke to Tamsin Gray and Jonathan Shanklin, both from the British Antarctic Survey about their work...
Ben - Tamsin, how do you have to adapt research to cope with those conditions?
Tamsin - Sometimes it's just really simple challenges like working outside, doing fiddly tasks with your hands. One of the tasks I had to do was go out and measure 10 metal poles in the snow to see how the accumulation of snow varies from year to year and sometimes, I would have to go back in the middle of the winter to warm my hands up in the middle because I could only measure 5 before they'd frozen. I won't tell you about the time when I held the metal tape measure to the pole with my mouth for a second whilst I did something with my hands.
Chris - Ouch! Show us your tongue? Oh it's still there.
Tamsin - It's healed just about. That was about 5 years ago and I think I've learned my lesson.
Ben - So, what actually is your research? What is it you're trying to find out?
Tamsin: - We're researching lots of different aspects of climate change. John and I work on atmospheric science. So, right from the kind of snow and what's happening at the snow air interface, up through the layer where we experience weather and then the ozone layer which I'm sure John will talk about above us, and then the upper atmosphere at the boundary to space, we research space where the Antarctic is actually a great place to study things like the Aurora. So, all aspects of the atmosphere that form the climate and the changes that are taking place that we're trying to understand at the moment.
Ben - We heard earlier about how atmospheric researchers here in Cambridge can deploy a network of sensors they strap to lamp posts which again, is not an option for you. And now, they're developing new technologies on these unmanned aerial vehicles that will allow them just to go up through the air column and measure everything. It can't be that simple for you. How do you actually measure that full column of air?
Tamsin - We've got a whole array of different instruments. We measure the upper atmosphere with big radars, so we often build masts and towers in Antarctica that can transmit strong radio signals up into atmosphere and bounce them off various sets of charge particles, and things that can give us information about what's happening way up in the atmosphere.
It was interesting in hearing what they were saying because one thing that we did one time when I was in Antarctica was fly unmanned aircraft because we wanted to find out what was happening over the frozen sea ice in the winter time when it wasn't safe to go out there as people, it was dark and it was freezing cold. Although we actually had some problems flying things by remote control because we were limited by the thumb freezing time which depended on the temperature we a graph.
Chris - That was pretty painful. Ouch!
Ben - So, do these limitations as well mean that it's very hard for you to collect a full, year-round data set or are you able to leave sensors there and collect data all year without actually having to go out into dangerous conditions?
Tamsin - We do have year-round data about lots of different places in the atmosphere that - I mean, some of it, we collect, we're involved in the collection. A lot of it, we now have automated instruments that are collecting them and they just need scientists and engineers to be able to fix them because nothing in Antarctica works smoothly. There's always problems and challenges, no matter what you do.
Ben - And Jonathan, if we could bring you in here, what sorts of things are you actually finding out?
Jonathan - I think one of the differences of say, the UK and Antarctica is the density of a network. So typically, weather stations in this country might be 50 km apart, maybe a little bit more than that, often, much less 10 km. In the Antarctic, we're lucky if we've got them several hundred kilometres apart.
So, that means that each station is much more valuable in itself in identifying what's going on. And we're looking at things on a variety of timescales. So, we're looking at the climate as it changes over the ice ages, in a really long timescales by looking at the ice itself. On the more historic timescale, we're looking at the slow change of climate in the measured period. Our Halley was first occupied in 1956. So we've got 60 odd years' worth of data from there.
Intriguingly, the temperature, the mean average temperature at Halley has not changed significantly in that period. And that contrasts with what's going on in the Antarctic Peninsula, the bit that sticks up towards South America which is warmed by 3 degrees at the same time. Now we say, "Why? What's going on?"
The answer is, the ozone hole is what's going on and it's quite fascinating that we're discovering that there are lots of indirect links between the climate and the ozone hole, and the ozone hole and climate. And one of the worries is, that the ozone hole really tells us about how fragile our atmosphere is. It came from virtually nothing, to full blown in a little over a decade when our finding that it's affecting the oceans around Antarctica.
What's happening is that the formation of that ozone hole each spring is changing the wind system lower down in the atmosphere which is then changing the ocean currents because the strength of the wind has changed. And we know at least in one or two places of Antarctica, that's then pushing warm water towards the Antarctica coast and is actually starting to melt from below some of the ice shelves. So it's a fascinating chain that links the two together.
Of course, with the changing climate in the surface due to the increasing amount of carbon dioxide and methane in the atmosphere, although that's warming the surface of the Earth, higher up, it's getting colder. And because the ozone hole forms because of the unique circumstances over Antarctica, we get a long period of really cold temperatures during the Antarctica winter, which allow clouds to form inside the ozone layer itself, and then the sun comes back in the spring, it illuminates those clouds, and on the surface of those clouds, chemical reactions have taken place that converts chlorine and other substances from things like Freons and other halocarbons interactive form. You then get photochemistry which destroys the ozone, creates the ozone hole.
Ben - It's a self-perpetuating problem really once you have an ozone hole in the first place that chemistry then will keep that hole going.
Jonathan - It will. However, one of the things that we globally have done about it is that all the member states of the United Nations have signed up to what's called a Montreal Protocol and this is a tremendously successful treaty. It's working. The amount of those ozone destroying substances in the atmosphere is going down and it's quite clear that they're going down, but they'll be with us or the ozone hole is likely to be with us for maybe another 50 or 60 years, just because these chemicals are so stable.
Chris - Is the hole shrinking though?
Jonathan - Yes, I think it is. It's still quite early days, but it is quite obvious in our averaging data from Halley that we're seeing a recovery. When you look at the lowest level of ozone that's seen each year, it's rather less clear cut. There's definitely a sign that things are improving, but we're within the noise level still. And also, that relies on there being no other external forcings and you could still get the perfect storm as it were where the atmosphere conspires in just the right way to give you exceptionally cold conditions, exceptionally stable atmosphere, combine that with a very big southern hemisphere volcanic eruption that puts extra particles up into the ozone layer and we could get the worst ozone hole ever. But within 5 or 10 years, I think that will be past, we'll have had the worst ever ozone hole and we can clearly say that through combined action, we have cured at least one of the environmental problems that are facing us.
Ben - That's incredibly positive news of course. We have been talking throughout the whole show about how different and special Antarctica actually is. Can we learn lessons from the research that we do down there about the climate systems for the rest of the world?
Jonathan - Yes, because what goes on the poles very clearly influences a much wider region. So, there's quite good evidence that because the ozone hole is changing the wind systems, that's changing rainfall patterns, and potentially affecting Australia. So, that's getting quite a long way north and so, the other side of it is, if we change how the oceans are being heated, then the ocean transport system which brings warm water from the equator, northwards and southwards, if we start tinkering with that pump, then we can have global effects on the climate.
Ben - Fantastic and you know you're talking about somewhere special when you're describing Australia. It's quite a long way north. Thank you ever so much Tamsin Gray and Jonathan Shanklin, both from the British Antarctic Survey.
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