A study of nine biophysical parameters suggests that humanity is stressing the entire Earth system. Unless people change their ways catastrophic environmental damage could be caused.
Nine Biophysical Limits Studied
The report of a study by 28 environmental scientists has been published in the journal Nature (September 24, 2009).
Nine areas were studied: climate change, stratospheric ozone, land use change, freshwater use, biological diversity, ocean acidification, nitrogen and phosphorus inputs to the biosphere and oceans, aerosol loading, and chemical pollution. Interestingly, the researchers have assigned numerical values to each factor and are, therefore, able to set a tipping point for them.
They say humans have already crossed the threshold in three areas and need to pull back.
Scientists Stress Biosystems Study is Preliminary
The study team was led by Johan Rockström of the Stockholm Resilience Centre and, according to Nature, the scientists say the values chosen as boundaries are somewhat arbitrary as are some of the indicators of change.
For example, says an editorial in Nature (September 23, 2009), “There is, as yet, little scientific evidence to suggest that stabilizing long-term concentrations of carbon dioxide at 350 parts per million is the right target for avoiding dangerous interference with the climate system.”
The point of the study, say its authors, is to start a scientific discussion that will lead to a refinement of the numbers.
Safe Operating Space for Selected Earth Boundaries
The scientists have placed numbers that biophysical boundaries should not be pushed beyond. Here are examples of boundaries that have been exceeded:
- Climate change - Atmospheric carbon dioxide concentrations not to exceed 350 parts per million; the current concentration is 387 ppm;
- Biodiversity loss - Biodiversity loss should be no more than ten times the background rates of extinction; currently species loss is between 100 and 1,000 times the natural rate; and,
- Nitrogen concentration – Reduce the flow of new reactive nitrogen into watercourses and oceans to 25 percent of its current value, or about 35 million tonnes of nitrogen per year.
Environmental Threats are Interconnected
According to the report, “A Safe Operating Space for Humanity,” each of the nine areas of concern has to be tackled at the same time. If one boundary is crossed there is a negative effect on the others.
“For instance,” say the authors, “significant land-use changes in the Amazon could influence water resources as far away as Tibet. The climate-change boundary depends on staying on the safe side of the freshwater, land, aerosol, nitrogen–phosphorus, ocean, and stratospheric boundaries.”
Prelude to Copenhagen Conference
Between December 7 and December 18 2009, senior officials will gather in Copenhagen, Denmark and try to develop a climate treaty to replace the Kyoto Protocol, which expires in 2012.
United Nations negotiators have been working for several years to lay the groundwork for this conference. Scientific studies form an important part of the negotiation process and the “A Safe Operating Space for Humanity” is intended to add to the technical background papers upon which a new climate agreement will be built.
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