Water, saviour from heat

Water minimises the climatic effects of a cooler or warmer sun, says Hsien-Wang Ou of the Lamont-Doherty Earth Observatory in Palisades, New York, USA. The Sun has got about 30 per cent hotter since the world began but the global average temperatures seem not to have varied much in either direction since then. The Earth has stayed indifferent to the Sun's changes. Some explain this so-called 'faint young sun paradox' by assuming that the early atmosphere contained more greenhouse gases such as carbon dioxide, which trapped a greater proportion of solar heat. Ou thinks that water alone is enough to buffer temperature against reduced or increased solar heating.