HIGH-RESOLUTION LAKE STABLE ISOTOPE RECORD OF CLIMATE CHANGE IN CENTRAL TURKEY DURING THE LAST TWO MILLENNIA

Lakes are a widespread palaeoresource and many are sufficiently sensitive to record late Holocene climate variations. Varved lake sediments provide a chronological framework from which changes in climate proxies can be observed on annual, decadal and century time scales and compared to other high resolution archives such as tree rings and ice cores.

An annually varved sediment record from a crater lake in central Turkey covering the last ~2000 years has been analysed for geochemical proxies of climate change, including stable oxygen isotope ratios, with the last 900 years at annual sampling resolution, and the preceding period at five-year sampling resolution. The resulting curves show significant variability over decadal and century time scales throughout the recorded time frame. Decadal scale cycles are observed (dominant periodicity of 62 years during the last millennium), as are large and rapid shifts in the isotope system, for example at c. 1400 AD.

Although lake chemistry systems are complex with many possible controlling mechanisms, statistical comparison of proxy data with instrumental climate records for the last ~70 years suggests relative humidity is a major driving factor behind oxygen-isotope changes in this lake. This in turn is likely to have varied in concert with regional changes in temperature and the P-E ratio.

The variability in this record suggests that Late Holocene climate in the eastern Mediterranean has been far from constant, with changes in the past 2 millennia at least on the scale of those observed in the last 100 years.