For the first time, a group of 28 scientists – including researchers from Wageningen University – has estimated what the safe boundaries are for the human effect on the global environment. This concerns boundaries on CO2 and other critical environmental components; these boundaries ensure that the Earth will remain liveable for future generations. They are presenting the new approach in last week's edition of Nature.
During the last 10,000 years, the climate of the Earth has been exceptionally stable. During this period, complex societies, such as ours, have been able to develop. Without human influence, this unusual stable epoch is expected to continue for thousands of years. According to the authors, however, the effect of humankind on the Earth is now so great that the possibility of radical transitions in the Earth system cannot be excluded.
According to Prof. Marten Scheffer, Wageningen professor and co-author of the Nature article, there is a high probability that drastic global changes will cause severe problems for humankind if certain critical boundaries are exceeded. One problem is that the time delay can be so large that the irreversible consequences of our current actions will only confront future generations. “As scientists, we argue that it is important to indicate as clearly as possible what the safe boundaries are within which we can be reasonably certain that humankind will be able to prosper for countless generations in the future”, says Scheffer.
The group of leading scientists, including government advisors such as Hans Joachim Schellnhuber (In Germany), Will Steffen (Australia) and Nobel Prize winner Paul Crutzen, emphasise that the indicated boundaries are tentative estimates. Their intention is to provide clarity for politicians and policymakers. “We are faced with a difficult dilemma", says Scheffer. "It doesn't do any good to just keep warning people. But you also cannot wait until the far-reaching transitions in the Earth system are a fact. Then it will be too late to do anything”.
Although our generation will probably not experience the great transitions referred to by the authors, Schellnhuber (Director of the Potsdam Institute for Climate Research) emphasises that the current rate of sea level rise during the past 10-15 years, along with the retreat of the Arctic sea ice and virtually all glaciers in the world, clearly indicate that the world climate has already begun to shift.
The authors state that safe boundaries must not only be established in the area of climate change, but also in other areas including freshwater consumption, extinction of species, the transport of nutrients to the oceans, chemical pollution and ocean acidification. The tentative estimates suggest that the safe boundaries have already been exceeded in three areas: climate change, species extinction and the nitrogen cycle. One complication is that the different boundaries are not independent; exceeding one boundary can increase the chance of having problems on other fronts as well.
“What we are arguing for,” says Scheffer, “is for scientists to establish a map that indicates clear boundaries within which we can continue to affect the Earth safely. The next step is up to the politicians. If we continue to deliberately exceed such boundaries, the following generations will not be happy with what we have done”.
Publication data
Feature article in Nature, September 24 issue: “Planetary Boundaries: A Safe Operating Space for Humanity”, as well as individual commentaries and reader responses: www.nature.com.
Background material: http://www.stockholmresilience.org/planetary-boundaries