If we reach a global climate deal in Copenhagen for stabilizing greenhouse gas emissions, will questions about the sustainability of -- and dangers to -- human civilization as we know it be put to rest?
Notso much, argues the author of a recent seminal paper in the British Journal, Nature, which identified NINE planetary boundaries that if crossed, endanger humanity. The Earth's climate system is just ONE of the nine boundaries that we have crossed or are in danger of crossing.
Says author, John Rockstrom:
In the run-up to the climate negotiations in Copenhagen, it is easy to get the impression that as long as we reduce emissions of greenhouse gases we will be safe from dangerous, or even disastrous, outcomes for humanity.
But mounting scientific evidence strongly suggests that is very unlikely.
In a recent article presented in the scientific journal Nature...We identified nine critical Earth system processes including climate change, depletion of stratospheric ozone, land-use change, freshwater use, rate of biological diversity loss, ocean acidification, amounts of nitrogen and phosphorus inputs to the biosphere and oceans, air pollution from aerosol loading, and chemical pollution.
Our scientific proposition, based on this new concept, is that as long as we stay within the boundaries for these nine, we give ourselves a long-term safe operating space for human development on Earth.
Climate change is, not surprisingly, one of the nine proposed boundary processes, and here we build on the latest climate science, which indicates that we may have to stabilize the concentration of carbon dioxide in the atmosphere to 350 parts per million (p.p.m.) in order to avoid nonlinear and potentially irreversible environmental change.
We are already at approximately 390 p.p.m., i.e., we are already in a danger zone.
Land and oceans have been providing a free ecosystem service, in the form of sinks that store carbon dioxide. As much as 50 percent of today's carbon dioxide emissions are absorbed by terrestrial and marine ecosystems.
But the capacity of this ecosystem service may now be decreasing due to temperature increases, acidification of oceans, and land-use changes.
And if we continue to warm and acidify the oceans and cut down forests, we risk not only collapsing ecosystems followed by increased human starvation, but also reducing or even reversing this free service nature provides us . If the planet turns from friend to foe, i.e., from sink to source, when eroding the resilience of the biosphere, we will enter a potentially disastrous domain of runaway climate change. To avoid such outcomes will require radical action not only on emission reductions but also on active stewardship of the world's ecosystems.
This is why reaching a substantive global agreement in Copenhagen on reducing greenhouse-gas emissions is necessary, but not sufficient for steering clear of catastrophic, irreversible tipping points in the Earth system.
To reduce the risk of tipping into the unknown, we need a new global deal for sustainable development.
As we head into the two minute warning here in the global game of human civilization, we've really got to put aside our differences and focus on getting the win.
Do we really want to leave ourselves vulnerable to surprises of the magnitude and consequences that the author is warning of?
Why should we, when the solutions -- which we report and comment on here daily -- offer so much promise.
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