Ice-thermal feedback-driven temperature variability on the Tibetan Plateau

Abstract

Despite globally parallel changes in insolation intensity, the nature and causes of Holocene stadial-interstadial transitions and relevant cycles remain mysterious. Particularly, the ice-thermal feedbacks caused by the ice sheet on the Tibetan Plateau have pronounced effects in the interannual surface-heat anomaly and local-to-remote atmospheric circulations. However, its long-term variations and impacts in terms of melt-freeze dynamics remain mysterious. Our results are based on decadal resolved difference between two oxygen isotope records during the past 12,000 years from Donggi Cona Lake, north-eastern Tibetan Plateau. They indicate surface-heat anomaly-caused air-temperature variabilities, which were about −3 °C in springs 9,500 years ago and 2 °C in autumns afterwards on average, independent from insolation strength. We find that increasing autumn air-temperature variability generated large-scaled vertical convections over the Plateau 4,500 years ago. Since then, the recent Tibetan Plateau thermal forcing centre formed with the noted increase in anthropogenic greenhouse gas emission. The predicted increasing autumn air-temperature with greenhouse effect portends future higher atmospheric sensitivity. We anticipate Holocene ice-ages to be tipping points of the coupled surface-atmosphere climate changes.