The United Nations has a warning: thresholds ahead.
Not only are the world's citizens failing to halt the increasing environmental strain felt across the globe, but some of the Earth's systems are nearing points of drastic, nonlinear change that could threaten both ecosystems and human development.
That's the warning advanced today by a major U.N. environmental report -- the fifth Global Environmental Outlook (GEO-5) -- prepared in advance of the U.N. Conference on Sustainable Development this month in Rio de Janeiro, known as Rio+20, which will bring a host of world leaders together to discuss the balance between growth and environmental degradation.
"If current patterns of production and consumption of natural resources prevail and cannot be reversed and 'decoupled,' then governments will preside over unprecedented levels of damage and degradation," said Achim Steiner, executive director of the U.N. Environment Programme, in launching the report.
With the report, the United Nations has reaffirmed its use of a controversial new metric for assessing the world's sustainable path: "planetary boundaries." Proposed three years ago in the journal Nature, the boundaries are roughly based on the limits estimated during the past 10,000 years of human activity, and they have been seized upon by policymakers seeking a guide to the future of life on Earth.
The endorsement of world leaders for such boundaries -- say, for example, a limit for atmospheric carbon dioxide, land-use change or biodiversity loss -- is expected to be a major rhetorical highlight of the Rio+20 summit. And unlike its predecessor two decades ago, which resulted in the U.N. Framework Convention on Climate Change and the Convention on Biological Diversity, Rio+20 is unlikely to score any international binding agreements, making the battle over its message especially important.
While planetary boundaries have been seen as a successor to global warming, climate change or biodiversity as a top-level message, some scientists have questioned the United Nations' rapid embrace of the concept. For example, instead of boundaries, the scientific focus should rest on "planetary opportunities," a high-profile group of scientists argues in the journal BioScience this month.
Indeed, there is a consensus, which includes many of authors of the original Nature paper, that the boundaries concept remains scientifically weak, is not grounded in physical limits -- except perhaps with climate change -- and has received far too much attention from the media, said Erle Ellis, a geographer at the University of Maryland, Baltimore, and co-author of the BioScience paper.
"Moreover, many [scientists] are convinced that focusing on the [boundaries] approach will weaken, rather than strengthen, the role of science in informing society in environmental decisionmaking," Ellis added.
This is not to say that scientists are not concerned about the world's passing certain irreversible thresholds, like the melting of ice sheets. Indeed, a review paper published today in Nature warns that the world could be approaching a "state shift" in its biosphere (see related story). But whether these thresholds, which contain so much uncertainty, should become a policy locus is another question, and one likely to run throughout the Rio+20 meeting.
Data collection lags
Beyond its embrace of boundaries, GEO-5 marks what progress has, and has not, been made over recent years, including separate regional reports. It surveys 90 international environmental goals and finds that significant progress has been made on only four: ozone-layer depletion, removing lead from fuel, increasing water access and research on marine pollution.
Another 40 goals, including the increase of protected areas and efforts to reduce deforestation, showed some progress, the report concludes. Meanwhile, for 24 goals -- including climate change, fisheries decline, desertification and drought -- the world has made almost no progress.
The report also nods toward current tropes of conservation, including the need for poverty reduction and environmental protection for human development, with a focus on the proper valuation and use of ecosystem services. Just attempting to halt the symptoms of environmental damage is not enough.
"Because of the complexities of the earth system, responses need to focus on the root causes, the underlying drivers of environmental changes, rather than only the pressures or symptoms," the report says.
A complication in writing the report is the lack of reliable, long-term monitoring of the world's environmental systems. This challenge is especially important when some of the world's wealthiest nations have threatened to cut their data collection budgets, added Amy Fraenkel, UNEP's regional director for North America.
"You can't manage what you can't measure," she said.
Not all is gloom, though, Fraenkel said. GEO-5 notes that when international agreements have set hard, measurable goals -- like many of the Millennium Development Goals -- they have often had success. It speaks to the weakness of many international environmental agreements that such measurable goals are uncommon.
Click here to see the report.