Hugh is an expert in the type of past rapid global warming events known as “Oceanic Anoxic Events” or “hyperthermals”. These were rapid warming events that occurred mainly in the Jurassic and Cretaceous, due to large volcanic eruptions releasing greenhouse gases such as CO2 into the atmosphere , and can be used to understand the current and future Earth’s response to rapid warming. Here we study how weathering changed, and therefore how quickly the atmospheric CO2 was removed again and therefore how the climate recovered.
Lithium isotope evidence for enhanced weathering during Oceanic Anoxic Event 2
The Ocean Anoxic Event 2 (OAE2) about 93.5 million years ago was marked by high atmospheric CO2 concentration, rapid global warming and marine anoxia and euxinia. The event lasted for about 440,000 years and led to habitat loss and mass extinction. The marine anoxia is thought to be linked to enhanced biological productivity, but it is unclear what triggered the increased production and what allowed the subsequent rapid climate recovery. Here we use lithium isotope measurements from carbonates spanning the interval including OAE2 to assess the role of silicate weathering. We find the lightest values of the Li isotope ratio (δ7Li) during OAE2, indicating high levels of weathering—and therefore atmospheric CO2 removal—which we attribute to an enhanced hydrological cycle.