The timebomb in the heart of Istanbul

In the fog, the minarets of Istanbul's Ottoman skyline fade into the sky. The streets turn wet and slippery and the Bosphorus smells of fish and charcoal. It also smells of oil from the tankers. These massive ships are constantly passing to and fro under the city's huge concrete bridges and emphasise this famous waterway's critical geostrategic significance. For those who live in this mega-city, some of these vessels also constitute the ultimate nightmare -  an accident involving a ship carrying liquid petroleum gas. Under the right conditions, it could explode like an atomic bomb, destroying the 3,000-year-old city and every living thing within a 50km radius.

This year's war in Georgia has raised the risk of an apocalyptic accident. But thanks to an obscure 1936 treaty, the Turkish government cannot insist upon blindingly obvious preventative measures. Imposed by the allies upon the newly independent Turkish state after the Great War, the Montreux Convention guarantees merchant vessels complete freedom to transport any goods at any time through the Bosphorus. The convention was designed to balance Russian and Western spheres of influence. In practice, it has created a zone of maritime lawlessness.

An obscure 1936 treaty has created a zone of maritime lawlessness

This is one of the most difficult waterways in the world to navigate: its convoluted structure requires ships to change course at least twelve times. Four of these turns are blind corners - approaching vessels can't be seen until it is too late. It carries four times the load of either the Panama or Suez canals. Notorious for strong currents, whirlpools, whipping winds, and sudden dense fogs, it is booby-trapped with high-tension electric lines, suspension bridges, and a myriad of small craft which ply its length and breadth.  
 
Every day, a 1.5m people commute by ferry from one side of Istanbul to the other, and every day, more than 2,500 vessels pass through the straits, including an average of 28 tankers, most of them carrying enough explosive material to turn these waters into an inferno. No one should be trying to navigate this passage without a skilled, experienced pilot - more than 85 percent of accidents on the straits involve unpiloted vessels - but nearly half of the ships from the post-Soviet states simply refuse to use one. Because of the Montreux Convention, the Turks can't force them to.
 
Since the collapse of the Soviet Union, the discovery of huge oilfields in and around the Caspian Sea has turned the Bosphorus into a liquid pipeline. In the past five years, cargo traffic through the Black Sea has risen by nearly 500 per cent; the flow of oil from the port of Novorossysk has more than doubled. Monstrous vessels full of oil, dangerous chemicals, nuclear waste and liquid gas - often skippered by drunken incompetents - have been pouring down from the Caucasus. Many of these tankers are rustbuckets that shouldn't be at sea, let alone passing right through the middle of a city of 15m people. Because of the Montreux Convention, Turkey can't ban them.
 
Ankara, frantic about the hazard posed by increasing energy traffic in the straits, has in recent years been pressing for the development of alternative energy routes, focusing on the Baku-Tbilisi-Ceyhan pipeline. But the conflict between Georgia and Russia displayed the limitations of this strategy when Russian bombers targeted the area around it, immediately interrupting supplies. It is still not back to full capacity. Gas flows through the Baku-Supsa pipeline were disrupted, too. The result: More pressure on shipping lanes through the Turkish straits.

Thousands of tonnes of pollutants have gushed and spewed into the Bosphorus

The danger is not theoretical. Hundreds of accidents have already happened. Thousands of tonnes of pollutants have gushed, spewed, dribbled and exploded into the Bosphorus. In 1979, a fully-laden Romanian oil tanker caught fire after colliding with a Greek ship. The explosion burned the crews to death and rocked Istanbul like an earthquake, shattering windows, turning the sky blood-red, and spilling 94,000 tonnes of burning oil into the Sea of Marmara (that is almost four times the amount of leakage from the Exxon Valdez).

Five years later, a Greek Cypriot tanker collided with another vessel in the straits, killing 30 and spilling 20,000 tonnes of oil. The Bosphorus was aflame for five days. In 1999, a 25-year-old Russian tanker ran aground and broke up near the southwest shores of Istanbul, spilling 800 tonnes of fuel. When in 2005 a ship carrying liquid petroleum gas sank, its seven tanks floated free for two days causing city-wide panic before they were retrieved.

In 2006, only a last-minute intervention prevented an unpiloted kerosene-laden tanker from crashing into the Dolmabahce Palace. This is not a safety record to set the mind at ease, particularly as inevitably the number of collisions increase exponentially with the intensity of the traffic.
 
A disaster in the Bosphorus wouldn't just cripple Istanbul: it could turn off the lights in much of Europe. Even a moderate oil spill could close the straits for months of clean-up, cutting off a substantial proportion of Europe's energy supplies and causing a worldwide economic crisis. The environmental costs would be incalculable.
Most people have never heard of the Montreux Convention - but a moment's miscalculation in these foggy waters might very well make it infamous. ·