The geologic record and a knowledge of Earth's physical, chemical and biological processes provide a framework for EOS scientists to contemplate the dawning of the Anthropocene epoch. Change is a quintessential feature of Earth history and large changes are commonly associated with massive disruptions of the biosphere. During the Neoproterozoic period, a catastrophic breakdown of the thermostat that regulates the balance of atmospheric carbon dioxide subjected Earth to at least two cycles of near-total glaciation. In the Phanerozoic, the fossil record of mass extinction offers a unique perspective on the biological impact of environmental change at a global scale and points to a fundamental link between plate tectonics, large igneous provinces and atmospheric composition as a driving force in biosphere collapse. Records of Late Cenozoic climate change, archived in polar ice sheets and marine sediments, shed light on the mechanisms of glacial cycles and the packaging of abrupt climate change events within these cycles.

The processes that drive environmental change are entangled, involving interactions between the land, air and sea and the influence of living organisms that together control the concentration of atmospheric carbon dioxide. Over geologic time-scales, fundamental questions concerning the global carbon cycle range from the consequences of evolutionary innovation in plankton and the influence of virally-mediated cell mortality to those of large-scale changes in continental layout and the circulation of the ocean and atmosphere. Numerical modelling experiments, constrained by observations, provide a powerful tool for understanding ocean and atmosphere variability and change in response to natural and anthropogenic forcings. Scale interactions can be complex, with global atmospheric dynamics influencing weather variability and vice versa. New analysis tools are being employed to examine the properties of atmospheric oscillations such as the El Niño-Southern Oscillation, Arctic Oscillation and Pacific Decadal Oscillations and their atmospheric teleconnections. Predictions of climate change in response to increased concentrations of atmospheric greenhouse gases are critically dependent on the effect of changes in cloud cover. The unknown feedbacks between clouds and climate and the representation of cloud processes are among the largest sources of uncertainty in global climate simulations. Earth's cryosphere is correctly regarded as a responder, indicator and amplifier of global climate change. During the last Ice Age, cryospheric processes appear also to have been agents of change, triggering abrupt climate change events that may have modern analogues.

Physical changes in the ocean have direct impacts on marine ecosystems. In the Arctic Ocean, the influence of sea ice on upper layer mixing and transport in the coastal waters is being studied with the aim of understanding the impact of climate variability on sea ice cover and on coastal marine ecosystems. In the Pacific Ocean, long data sets reveal large climate variability on the interdecadal time scale that appear to produce an ecosystem response. By studying the linkages between the physical and the biological changes on this time scale, the underlying mechanisms are being exposed. EOS researchers are studying the ecological energetics of salmon with a view to understanding the environmental drivers of bioenergetics in this species and the implications of global change for the future productivity of this important economic and cultural resource.

The international political response to the problem of controlling greenhouse gas emissions is unlikely to be timely or appropriate. If emissions are to remain largely uncontrolled, then technological approaches to carbon sequestration may provide a way forward. Toward this end, EOS scientists are identifying and evaluating novel CO2 sequestration pathways that might help to offset the present rise. Current research is focussed on the selective adsorption of carbon dioxide and methane in coal seams and on approaches to accelerating carbonation reactions in mine residue.

Signpost Contributions

Milestone Contributions

(* - more than 25; ** - more than 50; *** more than 100 citations.)