What Time is it? Early Anthropocene @theAGU & Straw Poll

This post was originally published on the Laboratory for Anthropogenic Landscape Ecology Blog.

It was a great week at the American Geophysical Union (AGU) Meeting in San Francisco, especially with the many sessions sponsored by IGBP – the international scientific program that brought you the Anthropocene – as part of its transition to Future Earth.

I gave a talk on the emergence of humans as a global force in the Earth System based on my recent centennial paper (Ellis 2015) in a session sponsored by the Global Land Project.

But the real highlight for me was the session I hosted together with Kees Klein Goldewijk and Jack Williams: “Dating the Anthropocene: Early Land Use and Earth System Change”, which was sponsored by IGBP and the Past Global Changes project (PAGES).

The session <details & abstracts here> led off with Mark Maslin, who gave a rousing recap of his major paper on the Anthropocene in Nature this year, arguing persuasively for an Anthropocene demarcated in 1610 by the “Orbis spike” (Lewis & Maslin 2015). Kees Klein Goldewijk provided updates on his early global land use reconstructions (HYDE going to 3.2 & 4.0). Mark Bush presented on the ecology of prehistoric Amazonia – with intensive land use along waterways but far lower levels elsewhere (Bush et al 2015). Feng He presented climate simulations backing up the claim that early land use changed climate millennia ago (He et al 2014). I presented Jed Kaplan’s latest work on early land use modelling and regional land change reconstructions.

All of this work will soon be advanced enormously by a major new collaborative international working group led by Kathleen Morrison, Land Use 6000 (LU6K), which aims to provide empirical global reconstructions of land use and land cover over the past 6000 years and earlier as part of the Land Cover 6000 project (LC6K) of PAGES.

The science on early human transformation of the Earth will only keep growing as it moves beyond its roots in Bill Ruddiman’s inspiring work (noted by almost every presenter), making me reminisce about first meeting Bill at AGU in 2008. An exciting example of what is yet to come is Kathleen Lyons’ exciting new work on anthropogenic biodiversity change more than 6000 years ago (Lyons et al 2015), which made an appearance in one of the talks.

But perhaps the most entertaining part of the session was our use of a cancelled presentation slot to conduct a straw poll of Anthropocene start times. With only 15 minutes available we kept it simple – no details, no frills, just a “beauty contest” of four start time proposals with each person in the room (n = 43) having one “Yes” vote, and one “No” vote.

Here is the tally for each proposal:

(A) Mid-Holocene (>5,000 BP)
         with widespread agricultural land use: 15 YES, 13 NO.
(B) ~1610 AD
        with the Columbian exchange (the “Orbis spike”):  5 YES, 6 NO.
(C) ~1760 AD
        with the Industrial Revolution: 10 YES, 6 NO.
(D) ~1950 AD
        with the “Great Acceleration” (bomb radionuclide marker):
        11 YES, 12 NO.

No big surprise that an Early Anthropocene was popular, given our session topic, but it was remarkable how controversial ALL the proposals are – very mixed results!

We therefore followed up with the question: Should the Anthropocene be formally recognized by the International Commission on Stratigraphy in 2016? (the current target date of the Anthropocene Working Group).

The answer? 16 YES, 24 NO (do this later), and 3 NEVER (an option demanded by several in the audience).

References cited

Bush, M. B., C. H. McMichael, D. R. Piperno, M. R. Silman, J. Barlow, C. A. Peres, M. Power, and M. W. Palace. 2015. Anthropogenic influence on Amazonian forests in pre-history: An ecological perspective.Journal of Biogeography 42:2277-2288. http://dx.doi.org/10.1111/jbi.12638

Ellis, E. C., D. Q. Fuller, J. O. Kaplan, and W. G. Lutters. 2013. Dating the Anthropocene: Towards an empirical global history of human transformation of the terrestrial biosphere. Elementa: Science of the Anthropocene 1: 000018. http://dx.doi.org/10.12952/journal.elementa.000018

Ellis, E. C. 2015. Ecology in an Anthropogenic Biosphere. Ecological Monographs 85:287–331. http://www.esajournals.org/doi/full/10.1890/14-2274.1

He, F., S. J. Vavrus, J. E. Kutzbach, W. F. Ruddiman, J. O. Kaplan, and K. M. Krumhardt. 2014. Simulating global and local surface temperature changes due to Holocene anthropogenic land cover change. Geophysical Research Letters 42:623–631 http://dx.doi.org/10.1002/2013GL058085

Lewis, S. L., and M. A. Maslin. 2015. Defining the Anthropocene. Nature 519:171-180. http://dx.doi.org/10.1038/nature14258

Lyons, S. K., K. L. Amatangelo, A. K. Behrensmeyer, A. Bercovici, J. L. Blois, M. Davis, W. A. DiMichele, A. Du, J. T. Eronen, J. Tyler Faith, G. R. Graves, N. Jud, C. Labandeira, C. V. Looy, B. McGill, J. H. Miller, D. Patterson, S. Pineda-Munoz, R. Potts, B. Riddle, R. Terry, A. Tóth, W. Ulrich, A. Villaseñor, S. Wing, H. Anderson, J. Anderson, D. Waller, and N. J. Gotelli. 2015. Holocene shifts in the assembly of plant and animal communities implicate human impacts. Nature http://dx.doi.org/10.1038/nature16447