LONDON -- The nine 'planetary boundaries' — environmental tipping points, beyond which the planet may not recover —– could soon be joined by a tenth one, if a proposal from a prominent scientist is accepted.
The concept of planetary boundaries was proposed in 2009 by Johan Rockström, executive director of the Stockholm Environment Institute, and Will Steffen, executive director of the Australian National University's Climate Change Institute, but has been debated ever since.
The nine original planetary boundaries are climate change, biodiversity loss, biogeochemical flow, ocean acidification, land-use change, freshwater use, ozone depletion, atmospheric aerosols and chemical pollution.
Each of these factors has a safe 'operating space', but once the boundaries are reached, 'the destruction becomes largely irreversible' with dire consequences for the planet and humans, said Steffen.
The concept of tipping points is being pushed for inclusion in the Rio+20 negotiations, but there has been no agreement over the exact thresholds for the boundaries, which some scientists say are too stringent, while others say they are not stringent enough.
Steven Running, who studies global ecosystem monitoring at the University of Montana, United States, suggested during the Planet Under Pressure conference in London yesterday (26 March) that there should be a tenth boundary: the amount of available biomass.
Presenting his idea for the first time at the conference, Running, who served on the board of the Intergovernmental Panel on Climate Change, is proposing the 'global net primary production' as an additional tipping point since it gives a clear signal about the health of ecosystems and would also be an important component of global carbon measurements.
He said this would be data-driven, and satellites could help quantify data over large land areas.
The new indicator would integrate inputs from at least five of the original planetary boundaries — including freshwater use, nitrogen loading (part of the biogeochemical flow) and land-use change — to come up with a more precise measure.
'These are measurable boundaries and we have over 30 years of solid data,' Running said, arguing that this would make it a solid indicator.
Katherine Richardson, one of the co-authors of the original planetary boundaries concept and a professor at the University of Copenhagen, Denmark, backed Running's proposal.
'There's no reason to believe that the nine limits we found are the only ones,' Richardson told SciDev.Net. 'Biomass is a very critical one since unlike other resources everyone has easy access to it.'