Inestimable stones, unvalu’d jewels

The covetousness goes beyond metals and oil. Two newish discoveries in particular tickle commercial fancies. One is gas hydrates—white, sorbet-like compounds that usually consist of methane molecules trapped in a cage of water. They were first found in permafrost in the 1960s and then, in the 1970s, on the slopes of continental shelves deep beneath the ocean floor.

Many scientists believe these hydrates together contain more energy than all the known deposits of fossil fuels, a possibility that makes them highly attractive to countries such as Japan and India, with little or no oil or gas. The oil companies, though, are cautious. Hydrates occur naturally in pipelines, and are unpopular because they clog the flow of oil. Extracting them would be intensely difficult. And methane, though it burns more cleanly than coal, absorbs a wider range of wavelengths of the Earth’s outgoing radiation than CO2. It therefore traps more heat, making it an even more pernicious greenhouse gas.

The second discovery is the strange variety of deep-sea life that is increasingly coming to light — quite literally. Some of it is to be found near “black smokers”, vents that occur along ridges in the middle of the oceans where two plates are spreading apart. In such places dissolved hydrogen sulphide comes out of the rock and suddenly cools, causing minerals to condense and create plumes of “smoke”. The first of these vents was discovered in 1977 on the Galapagos ridge by scientists in the Woods Hole Oceanographic Institution’s submersible, Alvin. A more recent discovery, on the South-West Indian Ocean ridge last year, was made by China’s research vessel, Dayang 1. Life at the dark depths where these vents occur gets its food and energy from the Earth, not from the sun — and much of it is strange. Here can be found sulphur-eating bacteria, scale worms that thrive in hot water at the tips of the smokers, and shrimps — blind, though they have eyes on the back of their heads — that can mend their DNA even after it has been highly irradiated. And below the crust in these volcanic parts micro-organisms have been discovered that may offer clues to the origins of life.

... contd.