Loess deposits and wind-blown dust
Wind-blown atmospheric dust is a major driver of global climate change. Dust impacts incoming solar radiation, changes cloud formation and drives changes in oceanic productivity. Sequences of wind-blown dust called loess have been deposited over 10s of millions of years and cover 10% of the continents, while dust is also incorporated into other sediments on land, in the sea and in ice. However, there are large gaps in our understanding of the source, activity and impact of dust in the geological past, meaning that dust is often not properly included in many climate models that forecast future climate. Plugging these gaps by establishing the source and flux of dust, the controls on emission and the associated climatic changes with dust deposition are therefore pressing research priorities.
We work on a number of aspects of past dust and climate change. Our research includes using radiometric dating techniques such as luminescence dating to constrain the timing and rate of dust and loess deposition, attempting to source the past activity of dust emitting regions using novel single grain geochemical, mineralogical and magnetic methods on single dust particles of a range of sizes, and reconstructing past climate changes recorded in dust deposits like loess. We also utilise mineral geochemical methods to trace the linked tectonic-climatic-surface process evolution of the Tibetan plateau and Eurasia generally, using the vast Miocene-Pleistocene Eurasian Loess deposits.
Some of our results suggest a key role for one of the world’s major sediment bearing rivers, the Yellow River, in driving loess formation in Eurasia. In addition, magnetic mineral evidence from underlying Pliocene red clay dust deposits points to a strong link between East Asian monsoon climate, closure of the Panama seaway, Pacific freshening and global cooling over the Pliocene-Pleistocene. Currently we are focussing on tracing the sources of the finest grained fraction of dust from sedimentary archives.
Here you can find more information about our ongoing project 'last glacial atmospheric dust and climate change in Europe', funded by the Swedish Research Council.