UCL News


Water calculations provide vital data on greenhouse effect

24 January 2003

Scientists at UCL have calculated exactly how water behaves - how the water molecule moves and what its precise geometry is - on a microscopic scale and more accurately than ever before. Water vapour, and not the much maligned carbon dioxide, produces most of the greenhouse effect on Earth (the absorption and retention of sunlight in the Earth's atmosphere) and so this discovery offers, the hope, for the first time, of calculating data vital in understanding the greenhouse effect. Dr Oleg Polyansky (UCL), working with an international team, has developed a high resolution predictive model for the spectrum of water using ten years' time on the fastest super-computer in the country.

In making their calculations, the team took account of the effects of quantum electrodynamics (one of the most arcane theories in modern physics) as well as a mixture of Einstein's relativity and the quantum theory of atomic particles. This allowed the team to make first-principle calculations which approach experimental accuracy for the first time.

Dr Polyansky said today: "Water vapour produces 60% of the greenhouse effect so knowing just how water works is vital to understanding issues like global warming and to help us do something about them".

"Only by using theories such as quantum mechanics, electrodynamics and relativity can we hope to understand even simple molecules under conditions where we just can't do laboratory experiments".

The team included: Dr Oleg Polyansky (first author), Paolo Barletta and Professor Jonathan Tennyson from University College London (UCL).

For further information please contact: Professor Jonathan Tennyson, Department of Physics & Astronomy 020 7679 7809.

Notes to Editors: High-Accuracy ab Initio Rotation-Vibration Transitions for Water is published in Science, 24th January 2003.