A DELTA-C-13 RECORD OF LATE QUATERNARY CLIMATE-CHANGE FROM TROPICAL PEATS IN SOUTHERN INDIA

STABLE-ISOTOPE ratios of carbon in soils or lake sediments1-3 and of o xygen and hydrogen in peats4,5 have been found to reflect past moistur e variations and hence to provide valuable palaeoclimate records. Prev ious applications of the technique to peat have been restricted to tem perate regions, largely because tropical climate variations are less p ronounced, making them harder to resolve. Here we present a deltaC-13 record spanning the past 20 kyr from peats in the Nilgiri hills, south ern India. Because the site is at high altitude (>2,000 m above sea le vel), it is possible to resolve a clear climate signal. We observe the key climate shifts that are already known to have occurred during the last glacial maximum (18 kyr ago) and the subsequent deglaciation. In addition, we observe an arid phase from 6 to 3.5 kyr ago, and a short , wet phase about 600 years ago. The latter appears to correspond to t he Mediaeval Warm Period, which previously was believed to be confined to Europe and North America6,7. Our results therefore suggest that th is event may have extended over the entire Northern Hemisphere.