Oil spills in the sea and on the land.

In the 1960s cars ceased to be a luxury for the rich and became an essential for most families in the West. Cars need petrol, which is refined from oil. The world has come to rely on oil, not just for transport but for industry as well. Huge new oil transport tanker ships were needed to cope with the demand: 'supertankers' that were bigger than anything ever built before: up to 500,000 tonnes and longer than four football pitches.

In March 1967, one of these ships, the Torrey Canyon, was sailing from Kuwait with 120,000 tonnes of oil. She was bound for the Milford Haven oil refinery in South Wales. The captain steered to the wrong side of the Scilly Isles and, going at full speed, the tanker hit the notorious Seven Stones reef. Her hull ripped open. She was the first supertanker ever to crash. The crew were rescued. But nobody had ever had to cope with a disaster like this before, and no-one really knew what to do. Oil was escaping from a hole under the waterline; the environmental damage this 'heavy' crude oil could do was unknown.

The weather worsened and the detergent wasn't dissolving the oil. Nothing the authorities did seemed to work.

Another 20,000 tons had escaped when the wind changed and the oil slick turned towards England. A week after the accident, oil surrounded Cornwall and was starting to

come ashore. 100 miles of beaches were polluted by the oil. After eight days of pounding, the Torrey Canyon broke in two and nearly half of all the oil poured out.

The British Government decided to set fire to the 20,000 tonnes that were still on board, a feat which had ever been done before. In April, the wind changed direction, the oil spill was blown out to sea, and mainland Britain was saved from the full impact of the slick. However, the oil polluted the holiday beaches of Guernsey in the English Channel and Brittany in France. It took the plants and animals over ten years to recover. For the first time, oil was seen as a menace to the environment.

By the 1990s the North Sea oil fields had been developed and exploited, and oil transport routes had changed. Oil was now transported in huge quantities from the North Sea to Canada. On 3 January 1993 the supertanker Braer left Bergen in Norway carrying 85,000 tons of light crude oil to Quebec. The weather was stormy, and the tanker was pushed towards the rocks of Shetland. The Braer went aground at Garths Ness. Almost immediately it started leaking oil, threatening the people of Shetland.

Dispersants, less toxic than detergents, were sprayed from aeroplanes, but with winds of 100 kph it was dangerous to continue.

Inflatable plastic booms were put across sheltered inlets and bays, to try to stop the oil coming ashore.

The spill had killed fish, sea birds and seals. In all, over 1,700 birds died.

But the storms had an unexpected effect. Over the next four days the weather worsened, and the oil was naturally broken up by the heavy seas. On 12 January, the Braer broke into three, and the rest of its 85,000 tons of oil was released. That too was broken up by the heavy seas. Sixteen days after the disaster, most of the oil had disappeared from the area. A lucky combination of light crude oil, ocean currents and fierce weather kept Shetland safe.

Siberia is a vast area of Russia, stretching from the Urals to the Pacific. The world's largest wetlands have a delicate ecology that is largely intact. But there are huge reserves of oil, and many new towns have sprung up over the last 30 years. Surgut is typical: a town of 300,000 in the Central Siberian oil field, nearly all of whose working population is involved in extracting oil. When the secretive Soviet Union became the more open Russian Federation, American oilmen were called in to help the struggling oil industry, and stories began circulating about a huge environmental disaster.

Wherever oil is being extracted in Siberia, a large proportion seeps onto the land. Pipelines are the only way to transport the oil, but harsh winter weather and poor maintenance cause pipelines to break. The leaks can go unnoticed for months on end. When the annual thaw comes, thick gooey crude oil is just below the surface. Mile after mile of swamp was covered and coated in oil.

The region is so vast that the extent of the disaster can only be guessed.

On the other side of the Ural mountains, the oil town of Usinsk, built only 20 years ago, controls the pipeline to St Petersburg. In 1994, there was a massive pipeline spillage, and although an earth dam was built to try to contain the oil, heavy rain washed it away and the oil spilled into the rivers. The damage cost 13 million pounds and 270,000 tonnes of oil had been wasted.

In 1996, to the south and in another Russian oil field, yet another oil leak added to the millions of tons of spilt oil that damage the Siberian environment. These oil spills kill delicate mosses which elk, moose and reindeer eat. The Huntimunsi people suffer because their lives depend on animals like reindeer. As a result, the Huntimunsi people have shrunk from 250,000 to only 20,000. Their lands and way of life are being poisoned by an oil industry that doesn't care.

In the harsh conditions of Siberia, permafrost absorbs spilt oil. It's now virtually impossible to clear up, so the ground will remain poisoned for centuries to come, the oil frozen underground.