Chris - As someone who has been to both the poles for his research, you have survived and come back. It's a horrible place thought, isn't it? How cold is it at the poles?
David - Well it must be said that we go mostly in the summer, so actually quite often we will be working on the ice in T-shirts because if the sun is at a high angle it's just like being in Switzerland and being warmed by the Sun. But at the South Pole, the coldest temperature has been -80 degrees centigrade, so about the temperature of liquid nitrogen really.
Helen - That's really quite cold!
Chris - Yes, it's pretty chilly! How does life survive there, or is it just a barren wilderness with nothing?
David - No, there's plenty of bacteria that are living in the uppermost snow on the south pole, and most of these organisms they kind of go down into a diapause or a hibernation, they just go into resting stages until conditions get better. Myself, I study microscopic algae that get caught up into ice in frozen sea water, and when temperatures get really cold they just switch down their metabolism to a basal rate and then wait for the conditions to get better. That's a general principal, same for polar bears really, as well.
Chris - So if you look in the ice, it's not the sterile thing that we think it is, there's quite a lot of life hidden in there.
David - There's a lot of viruses, a lot of bacteria... it's teeming with life. Even very ancient ice that is hundreds of thousands of years old, has bacteria that have been brought back to life when this ice has been retrieved from these deep ice cores that people are taking in Greenland and the Antarctic.
Chris - It's intriguing to me that we put into our deep freeze at home food to make sure that it wont go off. It suppresses the activity of life which degrades food, that's at about -20 degrees. You're playing around in those temperatures and you've got things that you say are thriving. So how do they survive and flourish in those temperatures?
David - So we've actually got bacteria that are moving around at -20, this is the same temperature as your freezer in the sea ice. One of the things they do is the produce a lot of slime; they produce a lot of mucous. They protect their cells within [the slime] and sit in this gel-like body that buffers them against a lot of the temperature and also saline stresses that they may come into contact with.
Chris - Is it true that things like Unilever, big companies like them, have borrowed from biology and solved the problem of how to make smooth ice cream by nicking the chemistry that some of these microbes have invented for themselves?
David - There's a whole new industry of bio-prospecting in the poles, and people are looking for enzymes that work at particularly cold temperatures, substances that make, as you say, ice-cream smooth at cold temperatures. There's a whole group of industries that are out there that are looking to the poles for solving many of these kinds of problems.
Chris - One of the things you said was that on a hot day it can be like you're on the ski slopes of Switzerland and you have to be careful not to get burned, because there's lots of UV. So 2 questions come out of that: One; how do these organisms not actually get zapped by the UV and B; if there's a massive ozone hole over Antarctica now, is that compromising these organisms?
David - A lot of the organisms that live down there are able to react very quickly to changing light conditions. They're able to produce a whole string of pigments and also special amino acids that they are able to produce their own sunscreens, if you like. In turn, these microalgae and bacteria that produce these substances are eaten by things like the crustacea, the krill, as I gather was mentioned last week. They take on these sunscreen compounds via their diet, basically.
Chris - Ah, so one borrows from the other.
David - Exactly.
Chris - That's neat, so can we nick that and use it to make better suncreams for us? Especially if this ozone hole gets any bigger?
David - I don't think we need to. But one of the things is that when the ozone hole was first identified, a lot of biologists got a lot of research money out of this as everyone thought that this is going to be catastrophic to biology in polar regions. I think the last 10-15 years of research has shown that it probably isn't as catastrophic as first thought, the biology is really able to cope pretty remarkably, actually.
Chris - So that's the hole in the ozone layer, but what about the other big problem which is said to be effecting Antarctica, which is global warming, and melting. There's conflicting stories, some people are saying some bits of Antarctica are getting warmer, some bits are getting colder, what's the real story and how does it all fit together.
David - I think what's interesting here is that we do have regions of the Antarctic, the Antarctic peninsula, which is probably the area of the globe that is heating up the most, or at the fastest rate. In general, it's thought that the Antarctic isn't really suffering as such from global climate change. Where things are really happening is up in the Arctic, where we know that in 2050 (so within our lifetimes hopefully) there will be no sea ice in the summer. There will be always sea ice in the winter, but there will be no sea ice in the summer in the 2050s.
Chris - What's melting it?
David - Just increase in temperature. Temperatures are increasing dramatically over the past 30 years.
Chris - Is that the sea temperature, so it's melting from beneath, or is that the air temperature, so it's melting from above?
David - It's both, actually, so the thought of an ice-free Arctic, it's great for the shipping companies, who are going to be able to use the North West passages and the North East passages. But for things like the polar bears that are getting so much press at the moment, and also for the ecosystem. There's a whole ecosystem that's based on having a frozen ocean for a whole year up in the Arctic. Of course, we don't know what the consequences will be.
Chris - Don't polar bears do something clever when they walk across ice, because they can in some way intuitively test where it will take them?
David - They can, they kind of splay their legs out and crawl, so they're spreading the load of their body, but it doesn't really matter if they fall through, to be honest, as polar bears are fantastic swimmers anyway.
Chris - Now, you said that Antarctica isn't really suffering that much, but what about the fact that the ice sheet Larsen B and then other ones which we've seen previously, they've actually been of the order of thousands of square kilometres of ice - is that not significant?
David - It's certainly significant, but these kinds of ice-shelf break-ups have been happening throughout geological time, so they're part of a natural process. An ice shelf comes to an end and breaks off. It is true though, Larsen B is on the Antarctic peninsula and it's very likely that that's associated with the warming of the peninsula area.
Chris - Do you think then that it's too late from this global warming point of view? Are we going to see unequivocal losses that we can't remedy, in terms of the ecosystems and environments, or do you think that if we do start acting now we can turn things around?
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David - No, I don't think we can start turning things around, and cyclical changes like this have been well known in geological time. In the past there was tropical plants growing up in the Arctic region, so this is nothing new. What we've done, I think in the last couple of hundred years, is we've increased the rate of change of something that was happening quite naturally. My guess is we can't turn things around, we're not going to stop this pack ice going in the Arctic. But it must be said that with many of these changes, we've seen big cycles in climate change in the past.
Chris - I suppose it's good news, as my sort of final point, for fishermen, because up in the northern hemisphere, where they've been restricted by quotas and declining fish stocks, some of them have taken to catching icebergs instead. I did read one story where there's quite a big market for the water from icebergs.
David - There has been lots of ideas throughout time of taking icebergs and dragging them to Arabian countries as a source of fresh water, and this is an idea that doesn't ever seem to go away.
Chris - There must be quite a lot of water locked up in an iceberg, there must be millions of tonnes.
David - There's massive amounts of water, especially when you add up the amount of water that's in an ice shelf or an ice cap. It's just staggering amounts.