快猫短视频

When the Soviet Union collapsed in 1992, Jean-Robert Petit had every reason to feel anxious. He was living in the most remote place on Earth, in a research station run and supplied by . . . the Soviets. High up on the Antarctic plateau, atop 4 kilometres of ice, Vostok is no holiday camp. It holds the world record for the lowest reported temperature (-89.6 掳C) and it takes two weeks to haul supplies there by land. But from these frozen depths has come an unprecedented record of climate change stretching back hundreds of thousands of years. The Soviets began drilling there decades ago. And Petit, from the Laboratory of Glaciology and Geophysics of the Environment in Grenoble, was among the first Western experts to go there to analyse the ice. Gabrielle Walker spoke to him about life at Vostok and his passion for ancient ice.

Why bother going to Vostok to study ice when there鈥檚 plenty of the stuff in other, more accessible parts of the world?

Vostok has the longest continuous record of ice in the world. It鈥檚 extremely deep and has accumulated very slowly. Not much snow falls in that part of the Antarctic, so the ice layers from each year are thin and the base of the ice sheet is incredibly old: perfect for studying climate change over hundreds of thousands of years.

When did you start going?

We first arrived on 31 December 1984, and since then I鈥檝e done nine seasons there.

What was it like to arrive on New Year鈥檚 Eve?

Oh, it was marvellous. When we arrived the temperature was -44 掳C. We got out of the plane and breathed in some fresh air. Then we said: 鈥淗ey, the temperature鈥檚 minus 44, and we can survive!鈥� I鈥檇 dreamed of going for 20 years. We made several attempts to get there in the 1970s, but only got within 800 kilometres because our equipment was very bad. So when they said to me, 鈥測ou have a plane ticket to go to Vostok, are you going?鈥� I said, 鈥渙f course鈥�.

Vostok station has the record for the lowest temperature ever reported. What was the coldest you felt there?

It once went down to -58 掳C-and that was in January, the middle of summer. Dumont d鈥橴rville, 1600 kilometres away in the coastal area, is much warmer. In summer the sea ice melts. You have birds, you have penguins. And the temperature rises to -5 or -6 掳C. Vostok has none of this. The annual average temperature there is -55 掳C and it can get as cold as -80 掳C.

What鈥檚 it like having to work at that temperature?

Terrible. After one hour you are completely frozen. All you can do is escape back inside as soon as possible. You have to know exactly what your limits are to avoid frostbite on your ears, nose and fingers. But it鈥檚 often not so bad. The summer temperature can reach -28 掳C, and in the Sun without wind it can even feel warm. You can go out wearing just a shirt.

What did you eat?

Mostly meat, cabbage and pasta. And I remember that everything was good except that there were no potatoes because they ran out at the end of the winter. You really miss potatoes, especially in soup. When new supplies of potatoes arrived, they tasted better than caviar.

What do you do for recreation?

Wash. At Vostok you have a bath once every ten days, in a sauna. You usually sit there sweating for a few minutes at 110 掳C and then dash outside where it might be -40 掳C. Then back to the sauna to sweat some more. It is a very efficient way to wash and relax. Afterwards you drink vodka with your friends.

Any times when you were afraid?

The only thing we were afraid of was getting injured. OK, we had two doctors, some operating tables in case of emergency and a dentist. But it was rough, old equipment. It was better not to break your arms or cut yourself.

Was anybody injured while you were there?

Thankfully no.

Were there any times when you wished that you could leave?

No. Never.

What does it feel like to be so isolated?

You don鈥檛 feel isolated, you know. Sometimes you can make radio contact with your family and sometimes not. But if you know they are OK and your work is going more or less OK, you don鈥檛 care so much what鈥檚 happening in the rest of the world. After all, if something happens, what can you do?

What was your worst moment?

In 1992 everything went wrong. The drill got stuck, a major drama, and people didn鈥檛 get their money because roubles were worth almost nothing. Also, the Russian Antarctic Expedition did not send in very good engineers and technicians with the new supplies. So Vostok had to close. We got grants from France to pay the Russians, so at least the workers and technicians at the Antarctic institute didn鈥檛 disappear. Then Russia started to recover. They were able to reopen the station, fund the drillers and find a way to remove the jammed drill.

How long were you there for, in your first season?

One-and-a-half months. We left Vostok on 10 February. And as we had to go back to Mirny, on the coast about 1400 kilometres away, we could fly or go by tractor. Mirny sends supplies to Vostok by tractor, in a train up to a dozen at a time. The journey takes a couple of weeks, but since we knew almost nothing about the environment along the route, we decided that I should travel back by tractor and collect some snow and ice samples

And how was that journey?

Very uncomfortable. The tractors have huge engines and the noise is like being behind a Boeing 747. Also, the temperature drops dramatically to below -55 掳C at night on the plateau in the middle of February. This meant stopping by day and travelling by night otherwise the engines wouldn鈥檛 restart. But it was too noisy to sleep when the tractors were moving. And when they stopped I had to go out to collect my samples. So for me it was 15 days without much sleep. When we arrived at Mirny there was a big celebration but for the next three days I was dead.

How did it feel to be out on the plateau on that journey?

You cannot stay outside for long. You have to go back inside and you鈥檙e left wondering how anyone manages to cross Antarctica without support, how Scott, Amundsen and all the other explorers ever reached their goals.

What motivated the Soviets to build a station at Vostok?

Partly, it was about developing a technology to drill deeply into the ice-and beating the Americans. This was during the Cold War, and by 1969 the Americans had already drilled down 2139 metres at their camp at Byrd station in West Antarctica. So when we arrived in 1984 and asked the drillers at Vostok what they were doing, they鈥檇 say, 鈥淥h, drilling.鈥� 鈥淎nd what is your objective?鈥� 鈥淭o reach 2200 metres.鈥� 鈥淲hy?鈥� 鈥淭o get the world record.鈥�

But the Soviets also wanted to do some science, right?

Yes. But the Soviets needed to collaborate with outsiders like us to study the ice properly. We got access to the ice core, they shared the credit for the scientific findings. That was the deal.

Your first findings from the ice core created a stir when they were published back in 1987. Why was that?

Because they were the first really strong empirical evidence that increasing carbon dioxide in the atmosphere leads to warming. The ice core pulled up by the Vostok drill gave us the first continuous record of changes in temperature and CO₂ levels over a period long enough to include an entire natural climate cycle.

How do you study the ice to get that record?

The ratio of oxygen-18 to oxygen-16 in the ice tells you the temperature of the Antarctic when the ice formed. From the air trapped inside bubbles in the ice you can tells how much CO₂ was in the atmosphere. Putting all those measurements together in 1987, we found that the Antarctic temperature rose by 10 掳C from glacial to interglacial periods. Changes in CO₂ levels account for about 50 per cent of that change. For the first time we had a nice correlation between temperature change and CO₂ levels stretching back 150 000 years. Only ice can tell you about this important relationship.

And since then?

The drillers at Vostok reached deeper levels that enabled us to study progressively older ice. At more than 3600 metres, it is the deepest ice core ever drilled. The record now stretches back 400 000 years and it covers the past four natural climate cycles.

But how can you be sure that the warming we are seeing now is not part of a natural cycle?

However far back you look in the Vostok core CO₂ levels have never been as high as today. If you plot levels over the past 400 000 years you have a gentle oscillation up and down. But the present value shoots off the graph. The highest level in the past occurred 300 000 years ago and was 300 ppm. The present level is around 360 parts per million. So it鈥檚 clear we鈥檙e doing something different to the climate.

The drill at Vostok is designed to pull up ice from depths of 3000 metres or more. What鈥檚 it like to handle?

It鈥檚 marvellous, like a crystal. It takes about two hours for the drill to reach the surface and, if there is an ice core inside it, you鈥檙e very excited, like a child waiting for Santa Claus. If the core is there you feel it with your finger. You unscrew the barrel from the main drill and two people remove the core, one at each end. It鈥檚 10 centimetres in diameter and 3 metres long. And precious. You know that you鈥檙e the first to see this ice, and discover what鈥檚 in it. It鈥檚 just water. But it鈥檚 marvellous water. In the bubbles trapped in the ice you have samples of air from an ancient atmosphere. You can understand why we get so miserable when the drill sticks.

Is the old ice different from the younger ice?

Of course! The main difference is to do with the air bubbles. In younger cores, from say 50 000 years ago, the bubbles make the ice white. But in very old ice, the bubbles are so compressed that they disappear and the ice looks like pure crystal-like glass with no defects. Look at a thin section through polarisers and you can see the many colours of the crystal grains. It鈥檚 the only pleasure a glaciologist has working in the cold room-looking at thin sections of ice. They鈥檙e beautiful.

If the old ice has no bubbles, how do you detect the gases?

There is still gas in the ice even if the bubbles are compressed. As soon as you melt and refreeze the ice, the bubbles reappear and the air escapes.

Any plans to return to Vostok?

I leave on Monday.