ORCID Profile
0000-0002-9141-0931
Current Organisation
University of Leeds
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Publisher: Research Square Platform LLC
Date: 23-09-2022
DOI: 10.21203/RS.3.RS-2084887/V1
Abstract: The Permian–Triassic Mass Extinction (PTME), life’s most severe crisis1, has been attributed to intense global warming triggered by CO2 emissions from Large Igneous Province volcanism2–8. It remains unclear, however, why super-greenhouse conditions persisted for around five million years after the volcanic episode, when Earth system feedbacks should have returned temperatures to pre-extinction levels within a few hundred thousand years8. Here we use fossil occurrences and lithological indicators of climate to reconstruct spatio-temporal maps of plant productivity and biomass changes through the Permian–Triassic and undertake climate-biogeochemical modelling to investigate the unusual longevity and intensity of warming. Our reconstructions show that terrestrial vegetation collapse during the PTME, especially in tropical regions, resulted in an Earth system with low levels of organic carbon sequestration and chemical weathering, leading to limited drawdown of greenhouse gases. This led to a protracted period of extremely high surface temperatures, during which biotic recovery was delayed for millions of years. Our results support the idea that thresholds exist in the climate-carbon system beyond which warming may be lified substantially.
Publisher: Springer Science and Business Media LLC
Date: 31-05-2023
Publisher: Elsevier BV
Date: 09-2023
Publisher: American Association for the Advancement of Science (AAAS)
Date: 14-10-2022
Abstract: Mapping the history of atmospheric O 2 during the late Precambrian is vital for evaluating potential links to animal evolution. Ancient O 2 levels are often inferred from geochemical analyses of marine sediments, leading to the assumption that the Earth experienced a stepwise increase in atmospheric O 2 during the Neoproterozoic. However, the nature of this hypothesized oxygenation event remains unknown, with suggestions of a more dynamic O 2 history in the oceans and major uncertainty over any direct connection between the marine realm and atmospheric O 2 . Here, we present a continuous quantitative reconstruction of atmospheric O 2 over the past 1.5 billion years using an isotope mass balance approach that combines bulk geochemistry and tectonic recycling rate calculations. We predict that atmospheric O 2 levels during the Neoproterozoic oscillated between ~1 and ~50% of the present atmospheric level. We conclude that there was no simple unidirectional rise in atmospheric O 2 during the Neoproterozoic, and the first animals evolved against a backdrop of extreme O 2 variability.
Publisher: Springer Science and Business Media LLC
Date: 20-10-2023
Publisher: Springer Science and Business Media LLC
Date: 25-09-2023
Publisher: American Association for the Advancement of Science (AAAS)
Date: 25-08-2023
Abstract: The body fossil and biomarker records hint at an increase in biotic complexity between the two Cryogenian Snowball Earth episodes (ca. 661 million to ≤650 million years ago). Oxygen and nutrient availability can promote biotic complexity, but nutrient (particularly phosphorus) and redox dynamics across this interval remain poorly understood. Here, we present high-resolution paleoredox and phosphorus phase association data from multiple globally distributed drill core records through the non-glacial interval. These data are first correlated regionally by litho- and chemostratigraphy, and then calibrated within a series of global chronostratigraphic frameworks. The combined data show that regional differences in postglacial redox stabilization were partly controlled by the intensity of phosphorus recycling from marine sediments. The apparent increase in biotic complexity followed a global transition to more stable and less reducing conditions in shallow to mid-depth marine environments and occurred within a tolerable climatic window during progressive cooling after post-Snowball super-greenhouse conditions.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Benjamin Mills.