Wind regime changes in the Euro-Atlantic region driven by late-Holocene Grand Solar Minima
Walsh, Amy A.
Blockley, Simon P. E.
Milner, Alice A.
Understanding atmospheric response to radiative forcing, including the intensity and distribution of wind patterns is critical as this might have important implications in the coming decades. Long-term episodes of reduced solar activity (i.e. Grand Solar Minima, GSM) have triggered rapid climate change in the past, recorded in proxy-based records, including varved sediments from Meerfelder Maar, Germany, where the Homeric GSM (~ 2800 years ago) was studied. This study reconstructs windy conditions during the same GSM from Diss Mere, another varved record in England, to support the solar-wind linkage in the North Atlantic-European region. We use diatoms as proxies for windiness and support the palaeolimnological and palaeoclimate interpretation with a multi-proxy approach, including sedimentological, geochemical, and biological (chironomids and pollen) evidence. The diatom assemblage documents a shift from Pantocsekiella ocellata dominance to Stephanodiscus parvus and Lindavia comta, indicating a shift to more turbulent waters from ~ 2767 ± 28, linked to increased windiness. This shift is synchronous with changes in 14C production, linked to solar activity changes during the GSM. Both proxy records reflect a rapid and synchronous atmospheric response (i.e. stronger winds) at the onset and during the GSM in the North Atlantic and continental Europe. In order to test whether this solar-wind linkage is consistent during other GSMs and to understand the underlying climate dynamics, we analyse the wind response to solar forcing at the two study sites during the Little Ice Age, a period that includes several GSMs. For this, we have used a reconstruction based on a 1200-year-long simulation with an isotope-enabled climate model. Our study suggests that wind anomalies in the North Atlantic-European sector may relate to an anomalous atmospheric circulation in response to long-term solar forcing leading to north-easterlies modulated by the East Atlantic pattern.