Climate change is currently one of the major challenges for our society. It has become urgent to understand the stabilization and recovery patterns of Earth’s climate system from extreme events to find mitigation and adaptation solutions. However, to date our knowledge on the natural capacity of Earth’s system to recover through long-term carbon storage processes is still limited. By placing current climate warming in the context of past extreme climate changes it is possible to get concrete observations and quantification from natural examples at different time scales. RECOVERY aims to fill this gap by providing a holistic understanding on how the Earth’s system can recover and stabilize over longer time scales.
Earth’s climate history has been punctuated by several warming events that were often associated with fast increase in atmospheric greenhouse gas levels linked to the onset of large-scale volcanism. The Toarcian Oceanic Anoxic Event (TOAE, Early Jurassic) was one of the most extreme hyperthermal events in Earth history and can hence provide keys on how biogeochemical cycles have controlled Earth’s carbon cycle-climate dynamics over geological time scales. Taking the TOAE as a case study, RECOVERY aims to better understand the causes and feedback mechanisms that can enable the Earth’s system to recover and to adapt to large environmental perturbation events.
The onset of the TOAE is relatively well understood, whereas the long-term palaeoenvironmental evolution in the aftermath and the mechanisms leading to the recovery have received less attention. Although several studies have provided local records with sedimentological and geochemical evidence for increases in continental weathering and organic carbon burial rates during the TOAE, globally integrated records are still lacking. This is hampering our holistic understanding of the respective role and efficiency of continental weathering and organic carbon burial in the carbon cycle-climate recovery. By using a multidisciplinary approach and state-of the-art mineralogical and geochemical proxies, RECOVERY is filling this knowledge gap by providing the palaeoclimatic and palaeoenvironmental evolution from the onset of the TOAE to the recovery, and by constraining the feedback mechanisms responsible for the recovery and long-term climate and carbon cycle stabilization.
RECOVERY’s specific objectives were:
(1) Providing globally integrated records of the long-term (from onset to recovery) palaeoenvironmental conditions. Four studied sites were selected: Fontaneilles (France, Subalpine Basin), Acerillo (Chile, Andean Basin), Vilyui (Russia, Siberian Basin) and Ait Athmane (Morocco, High Atlas Basin). These sites were chosen to have records from both northern and southern hemispheres and from different palaeoceanographic settings. The multiproxy approach used in this study, which combines field observations, mineralogical and geochemical analyses, allow us to detangle the influence of regional processes on global trends.
(2) Reconstructing the carbon cycle dynamics, using carbon isotope composition (13C) of marine organic matter and marine carbonates.
(3) Evaluating changes in redox conditions, nutrient level and primary productivity using trace element concentrations.
(4) Tracking the causality link between volcanic activity and environmental changes, by means of mercury and tellurium concentration in the sedimentary rocks.
(5) Tracing the response of silicate weathering to global warming, using lithium isotopes and assessing its efficiency compared to organic matter burial.
