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Planet may be near tipping point, study warns

STANFORD (US) — The planet may be nearing a critical threshold, beyond which environmental changes will be rapid and unpredictable, according to a new study.

Most current predictions of environmental change are based on extrapolations from current trends. But what if that isn’t an accurate picture of the future? What if we are approaching a critical threshold—one that, once crossed, would lead to accelerated, widespread and largely unpredictable environmental degradations?

This is the alarming conclusion of a paper co-authored by Stanford University biology professor Elizabeth Hadly that appears in the new issue of Nature—an issue devoted to the environment, in anticipation of the United Nations’ June 20-22 Conference on Sustainable Development.

The consensus statement by 22 respected scientists uses past examples to suggest that Earth’s current systems will experience a major disruption—perhaps within a few generations.

“The environment will enter a new state,” says Hadly. “And we don’t know exactly what that state will look like.”

Tipping point

It’s already established that global biological systems are capable of very rapid, wholesale shifts. Of the five major extinction events in Earth’s history, at least four of them were accompanied by this kind of critical transition. Global conditions that had remained relatively stable for millions of years changed dramatically over a period lasting less than 5 percent of that time.

There’s reason to believe that “pronounced change” in “assemblages of species,” as the paper puts it—such as extinction events—are a reliable marker of these shifts. And we happen to be in the middle of an ongoing human-driven mass extinction.

The litany of ways in which humans have altered the Earth’s environment is well known. But why do these scientists now believe that we are moving toward a major, irreversible shift?

“There’s the idea that, once you have more than 50 percent of wholesale disturbance in a given ecological system, major disturbance in the rest of the system will inevitably follow,” says Hadly, who is also a senior fellow at the Stanford Woods Institute for the Environment.

About 43 percent of Earth’s land has already been converted to agricultural or urban use and, if current trends continue, is expected to reach the 50 percent mark by 2025. By 2060, using current trends, the number will be 70 percent.

By comparison, the last critical shift Earth underwent was the end of the last Ice Age. That famously dramatic example of climate change only involved ice melting from 30 percent of Earth’s surface, and it resulted in a major transition in global climatic conditions and the distribution of life on the planet.

Yellowstone example

Yellowstone is the nation’s oldest national park—it has been protected since 1872. So when Hadly saw several years ago that its wetland cover and amphibian populations were both declining, she was a little surprised.

“Practically its entire watershed is protected,” she said. “These changes weren’t caused by something from inside the park.”

Yellowstone was providing evidence to support a growing suspicion held by Hadly and a large number of other prominent environmental scientists.

What Hadly saw in Yellowstone suggests these global shifts may already be affecting isolated, local environments.

“As an ecologist, I was trained to measure changes on a local or a regional level—looking at changes in a 1-by-1-meter plot,” says Hadly. “Now, there’s a heck of a lot of change in that 1-meter plot that has nothing to do with local processes.”

The global drivers that are working their way into every corner of the planet all have humans behind the wheel. Human population growth and increased resource consumption mean that anywhere from 20 to 40 percent of the planet’s energy produced by living things now goes to support human society.

The ecosystems that do survive are becoming more homogeneous and simpler—a combination of human-introduced species and habitat degradation and fragmentation.

“We’re fairly naïve in managing for new combinations of species that will exist,” Hadly says, “in part because we usually anticipate ecosystem change on a species-by-species basis.”

Human connection

Although the exact nature of Earth’s next state is unpredictable, the researchers expect it to resemble an accelerated version of these already-in-motion processes.

These shifts are potentially disastrous for humanity as well.

“Citizens of wealthy countries like the U.S. are less aware of catastrophic shifts in ecosystem services because we have the ability to cobble together short-term fixes that mask the global trend,” says Hadly. “But other countries aren’t so buffered.”

In a world marked by water shortages and climate change, “we simply aren’t yet equipped with a flexible intergovernmental structure necessary to manage for this future.”

The United States may be buffered, but it can help with a crucial environmental task: monitoring ecosystems for evidence of this shift. America is large and geographically diverse enough that, Hadly says, “we could be some of the first to observe these changes, and if we are proactive, we can bear witness to the rest of the world.”

More news from Stanford University: http://news.stanford.edu/

chat6 Comments

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6 Comments

  1. MIke

    I think its important for scientists to study trends in the North Atlantic Flow, which will reach a desalination point much sooner than the human race will be able to repair. Global warming will cause more glciers to melt, spilling too much fresh water for the flow to handle. It will be like the movie ” The Day After Tomorrow”…. And I’m not a scientists and I read enough to know its a problem. Just that right there will affect the entire planet in a way that will change it forever…

  2. jims33

    Science says we’re not causing it and can’t change it.

  3. Lawrence Turner
  4. Barbara J Correro

    I live in Kemper County, MS. I moved on this area of 24 acres in 1999. I am a gardener. Therefore, I am outside most of the time except in inclement weather. I have personally experienced the changes in the seasons. This year I started planting my seedlings in March. Now my growing season is almost six weeks ahead than it was in 1999. In 2010, the third week in June was in the high 80′s. This year I experienced that in April.

    Unfortunately, there is a coal plant being built approximately six miles from this place. This is going to affect so much here including the air and water. This area of Kemper County is covered with creeks and small ponds. This monster of a coal plant with all it filth mining lignite will increase the warmth of the earth and destroy the wonderful area here.

    I just do not know what it is going to take for people to wake up. It is the human factor that is bringing on the warmth of the earth.

  5. Baka Karasu

    If you really care about this, stop making babies. It’s the one step we can all take that has the most significant long term global impact. See http://www.paulchefurka.ca for the best single site on this topic. Suggest starting with “The Elephant in the Room”.

  6. Kimberley

    I feel so helpless when I read about this, this is the most important challenge we have ever faced, as a species, and everyone is ignoring it. What can we do as individuals? Baka is right but we need to do so much more besides.

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