Planetary Boundaries

Found via a footnote at Nature

Planetary Boundaries: Exploring the Safe Operating Space for Humanity (2009)

Johan Rockström, Will Steffen, Kevin Noone et al
"ABSTRACT. Anthropogenic pressures on the Earth System have reached a scale where abrupt global environmental change can no longer be excluded. We propose a new approach to global sustainability in which we define planetary boundaries within which we expect that humanity can operate safely....We have identified nine planetary boundaries and, drawing upon current scientific understanding, we propose quantifications for seven of them. These seven are climate change (CO2 concentration in the atmosphere <350 ppm and/or a maximum change of +1 W m-2 in radiative forcing); ocean acidification (mean surface seawater saturation state with respect to aragonite ≥ 80% of pre-industrial levels); stratospheric ozone (<5% reduction in O3 concentration from pre-industrial level of 290 Dobson Units); biogeochemical nitrogen (N) cycle (limit industrial and agricultural fixation of N2 to 35 Tg N yr-1) and phosphorus (P) cycle (annual P inflow to oceans not to exceed 10 times the natural background weathering of P); global freshwater use (<4000 km3 yr-1 of consumptive use of runoff resources); land system change (<15% of the ice-free land surface under cropland); and the rate at which biological diversity is lost (annual rate of <10 extinctions per million species). The two additional planetary boundaries for which we have not yet been able to determine a boundary level are chemical pollution and atmospheric aerosol loading. We estimate that humanity has already transgressed three planetary boundaries: for climate change, rate of biodiversity loss, and changes to the global nitrogen cycle. Planetary boundaries are interdependent, because transgressing one may both shift the position of other boundaries or cause them to be transgressed. The social impacts of transgressing boundaries will be a function of the social–ecological resilience of the affected societies. Our proposed boundaries are rough, first estimates only, surrounded by large uncertainties and knowledge gaps....."
.http://www.stockholmresilience.org/download/18.8615c78125078c8d3380002197/ES-2009-3180.pdf

Supplemental material for the above paper:
http://www.stockholmresilience.org/download/18.1fe8f33123572b59ab800016603/planetary-boundaries-supplementary-info-210909.pdf

Boundary descriptions:
http://www.stockholmresilience.org/research/researchnews/tippingtowardstheunknown/thenineplanetaryboundaries.4.1fe8f33123572b59ab80007039.html

Table of Planetary boundaries:
http://www.stockholmresilience.org/research/researchnews/tippingtowardstheunknown/quantitativeevolutionofboundaries.4.7cf9c5aa121e17bab42800043444.html

Stockholm Resilience Centre
http://www.stockholmresilience.org/2.aeea46911a3127427980003200.html

Video on what is resilience?
http://www.stockholmresilience.org/research/whatisresilience.4.aeea46911a3127427980004249.html