Warm Periods in Deep Time
Past periods of global warmth can provide extraordinary insights into climate and life on the planet, beyond the range of recent experience. I am particularly interested in the operation of the climate system during warm periods that represent “modest greenhouse” conditions (mid Miocene, early-mid Pliocene, interglacials). Such climates provide a context for our current and future climate.
The mid Miocene represents a climatic period with greenhouse gas levels that were probably about the level projected for the end of this century. Evidence from the ANDRILL core indicates that plants grew on the margins of Antarctica (Warny et al., Geology, 2009). My research uses plant leaf waxes to reconstruct the high latitude hydrological changes that accompanied this high latitude vegetation expansion, and integrates the leaf wax results with climate model and pollen evidence.
Feakins, S.J., Warny, S. and Lee, J.E., (2012) Hydrologic cycling over Antarctica during the Middle Miocene warming, Nature Geoscience, doi:10.1038/NGEO1498. article
see also press page
Using similar approaches Late Eocene conditions were explored with leaf wax, pollen, climate model data, to see what hydrological and climatic conditions were like before the onset of full Antarctic glaciation.
Feakins, S.J., Warny, S., DeConto, R. M., 2014. Snapshot of cooling and drying before onset of Antarctic Glaciation, Earth and Planetary Science Letters, 404, 154-166. article
Currently our work on warm periods is focusing on tropical locations around the Indian Ocean including biomarker records of climate and vegetation from Pliocene age sediments from Gulf of Aden, and with ongoing laboratory work on drill cores recovered from recent IODP Expedition 354 to the Bengal Fan and IODP Expedition 355 to the Indus Fan we are now reconstructing the long history of the Indian Monsoon.