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El Niño
The El Niño Southern Oscillation (ENSO) is a huge, unpredictable climate system that alternately brings drought and flood to the Pacific and Indian Oceans. The most recent El Niño event is currently petering out and now Australia, having suffered its longest drought period on record, is cautiously optimistic that rain will soon start to fall as La Niña, the other extreme of the oscillation, is likely to develop. Press reports have suggested that this last El Niño event might lead to 2007 being globally the hottest year on record.

But has the earth been here before? Oceanographers have been investigating the possibility that 2-4 million years ago, when there were more greenhouse gases and the earth was warmer than now, the region was afflicted by a permanent El Niño. Quentin is joined By Alan Haywood, palaeoceanographer at Leeds University, and John Hammond of the ´óÏó´«Ã½ Weather Centre to discuss the lessons for our future.

Leonard Euler
Leonard Euler (15 April 1707 – 7 September 1783) was the most prolific mathematician who ever lived. His output was vast, and there are precious few areas of mathematics that were not touched by his genius. From practical problems of his day, such as the design of sailing masts and municipal lotteries to the highest reaches of pure maths and number theory, his own work accounted for approximately one third of all the maths published in the 19th century.

Joining Quentin this week is maths historian Robin Wilson, professor of pure maths at the Open University and Gresham Professor of Geometry in London, and Dr Julian Havil, maths teacher at Winchester College in Hampshire.