2nd GEOSS Science and Technology Stakeholder Workshop GEOSS: Supporting Science for the Millennium Development Goals and Beyond Bonn, Germany, August 28—31, 2012

Observing the Anthropocene - The Geology of Humanity

James P.M. Syvitski
CSDMS Integration Facility, INSTAAR, U. Colorado—Boulder, CO, USA James.syvitski@colorado.edu

Momentum is building to officially declare the Anthropocene a new geological epoch. Epochs are by themselves merely subdivisions of Earth's geologic timescale; it is what happens during these intervals that gives epochs their unique characteristics. Humans have changed the Earth in a number of fundamental ways and IGBP's Great Acceleration graphs collectively highlight the accelerating human enterprise and its impacts on the biophysical Earth system. Granted there are large regional variations, but the impacts on at least some components of the biophysical Earth System have been global and represent similar temporal trends. Atmospheric carbon dioxide, global surface temperatures, human-induced nitrogen fluxes to the coastal zone and species extinctions have all increased. Striking is the extent and rate at which we have modified Earth's surface. Deforestation for wood and land clearing for cultivation are examples that have greatly impacted soil erosion, hill slope failure and downstream sedimentation. Infrastructure - dams, cities, transportation networks and coastal management measures - has also led to lasting and profound impacts. Humans now easily match the capacity of rivers to move sediment in diverse ways. The large dams we have built during the past two centuries trap more than 2.3 Gt of sediment per year in reservoirs. This starves deltas of sediment, and in combination with the mining of water, oil and gas, has led to a situation where large deltas are sinking at four times the rate of sea-level rise. Humans now irrigate deserts throughout the world. We have delayed the flow of freshwater to the ocean by weeks to months through diversions and reservoirs. By any unbiased and quantitative measure, humans have affected the surface of the Earth at a magnitude that ice ages have had on our planet, but over a much shorter period of time. As this is an unfolding story of a change in our Earth system, we must continue to deploy and maintain appropriate observing systems. But we need to do better than repeat the business-as-usual approach that favours observations of the more easily sensed atmosphere and oceans. Monitoring the complexities of the terrestrial environment effectively is just as important.

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