Current Research in EEPS: Dr. David McGee, MIT
Saharan dust and North African climate over the last 250,000 years
The Sahara Desert is the world’s greatest source of mineral dust to the atmosphere, and records of Saharan dust deposition in marine sediments are a basic part of our understanding of North African climate evolution over the Plio-Pleistocene. Despite the importance of Saharan dust reconstructions for understanding local and global climate, it has been unclear how well we can actually reconstruct Saharan dust deposition, how dust emissions relate to the strength of the West African monsoon, and by what magnitude Saharan dust emissions change in response to orbital variations, glacial-interglacial changes, and millennial-scale climate variability.
We have used Th-230 normalization to map Saharan dust inputs across the North Atlantic over the last 20,000 years, demonstrating strong coherence of records from both sides of the Atlantic, between summer and winter dust emissions, and other proxy indicators of West African monsoon strength. Building on this work, I will present a record of Saharan dust deposition extending as far back as 240 ka. Our results indicate that previous long-term dust records have underestimated precessional variability and overstated the importance of glacial-interglacial changes over the past two glacial-interglacial cycles, and potentially over the whole of the Pleistocene. Time permitting, I will also present some preliminary dust and leaf wax reconstructions spanning the period from 350-550 ka.