K-feldspar-rich meteorite ejecta blankets suppress the cloud-albedo feedback and trigger Earth crises.

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Authors

Matt Pankhurst, Christopher Stevenson , Beverley Claire Coldwell 

Abstract

Meteorite impacts load the stratosphere with dust and cover the Earth’s surface with debris. They have long been debated as a trigger of mass extinctions through Earth’s history. Impact winters generally last <100 years, whereas ejecta blankets persist for 103-105 years. Here we show that only meteorite impacts that emplaced ejecta blankets rich in K-feldspar correlate to Earth-system crises (n=11, p<0.000005). K-feldspar is a powerful ice-nucleating aerosol and plays an important role in cloud microphysics, which modulates global albedo. We propose that each K-feldspar rich ejecta blanket caused a departure from the normal function of atmospheric dust in the climate system. The dramatically increased proportion of K-feldspar had two key effects on cloud dynamics and, in turn, the global climate: 1) reducing the average albedo of mixed-phase cloud, which effected a hotter global climate; 2) weakening of the cloud albedo feedback, which meant the global climate became more sensitive. Increased climate sensitivity allowed normally benign processes to become significant drivers of climate change, and potential kill-mechanisms. This may explain why many well-established kill-mechanisms only variably correlate with extinction events through geological time: they require a sensitized climate to produce change. Together, cascading effects were catastrophic for life: every K-feldspar rich impact corresponds to a severe extinction episode over the past 600 Myrs.

DOI

https://doi.org/10.31223/X5RK6C

Subjects

Applied Statistics, Atmospheric Sciences, Earth Sciences, Geology, Other Planetary Sciences, Paleontology, Physical Sciences and Mathematics

Keywords

Meteorite impact; K-feldspar; mass extinction; ice nucleation; cloud

Dates

Published: 2021-05-24 11:00

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
The authors declare no conflict of interest

Data Availability (Reason not available):
All data underpinning the analysis in this MS is already in the published literature. Supp Material also will be made available.

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