On 10 May 2013, 400 parts per million of CO2 concentration in the atmosphere was recorded at the Mauna Loa Observatory, Hawaii. This seemingly innocuous number failed to grab the attention of mainstream media, but it inadvertently signaled a quiet earth revolution – a geohistoric moment of “wild destratification”, as Deleuze and Guattari would have it. At the start of the Industrial Revolution (and the designated origins of the Anthropocene), atmospheric CO2 was at 280 ppm. The last time CO2 levels hit 400 ppm was in the Pilocene (between 2.6-5.3 million years ago). In light of these potentially seismic changes in the atmosphere and society, Society and Space invited some interdisciplinary reflections on 400 ppm.
Sara Nelson, Harlan Morehouse, Jessi Lehman and Elizabeth Johnson introduce 400 ppm with a special report on recent “Critical Climate Change Scholarship.”
Bronislaw Szerszynski takes us on a journey through aeons and epochs in “400 ppm and the ages of the Earth.”
Nigel Clark considers acts of fidelity to shifting geo-climatic regimes and geopolitical reconfigurations of the strata in “Regime Change in Geo-Social Formations.”
Martin Mahony examines Keelings early CO2 observations and the new cosmopolitical spaces of the atmosphere in “Geographies of a Global Experiment.”
Simon Dalby focuses on globalization as a process of material transformation in “Anthropocene Geopolitics.”
Angela Last examines our material existence in “Passing a New World Threshold?”
Jamie Lorimer takes inspiration from Primo Levi’s account of Carbon in The Periodic Table to reflect on “The 400th Part Per Million.”
Mark Whitehead puts reflects on round numbers, fogs and nonevents in history of the atmosphere in “Riding the Keeling Curve: Indifference and Round Number Theories of History.”
Eva Lövbrand and Björn-Ola Linnér ask what this iconic symbol of anthropogenic climate change means for the politics of climate change in “Wither Carbon Accounting? On the Political Effects of 400 ppm.”
Mike Hulme address how 400 ppm of CO2 symbolises the human alteration to one of the basic biogeophysical conditions of life on Earth in “Symbolism, Dread and Panic.”
Lesley Head addresses the need for new thinking around climate change in “Coping with Abundance Rather Than Scarcity.”
Richard Betts from the Met Office considers how carbon sinks maybe providing a partial offset of human emissions in “400ppm? We’re Lucky It’s Not 500 Already.”
