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BIODIVERSITY: Scientists Foresee Extinction Domino Effect

Stephen Leahy

BROOKLIN, Canada, May 17 2007 (IPS) - Climate change is accelerating species extinctions and unraveling the intricate web of life, experts fear.

Birds, animals, insects and even plants are on the move around the Earth, trying to flee new and increasingly inhospitable local weather conditions. For some, including alpine species and polar bears, there is nowhere to go. And many others, like plants, lack the mobility to stay ahead of changing climatic conditions.

“We’re already seeing species moving, but they’re not moving fast enough to avoid potential extinction,” says Jeremy Kerr, an ecologist at the University of Ottawa in Canada.

“The really awful predications about rapid, massive extinction appear to be true, according to the early evidence,” Kerr told IPS.

One of those predictions came last year from the Millennium Ecosystem Assessment (MA), an unprecedented international four-year research effort. The MA warned that up to 30 percent of all species on Earth could vanish by 2050 due to unsustainable human activities.

By 2100, it will be a completely different planet if greenhouse gas emissions continue rising at the current rate. Nearly 40 percent of Earth’s continental surface may experience totally new climates, primarily in the tropics and adjacent latitudes, as warmer temperatures spread toward the poles, said a new study published this month by the Proceedings of the National Academy of Sciences.

“We are going to be seeing climates that certainly are completely outside the range of modern human experience,” said Stephen Jackson of the University of Wyoming in a statement.

Scientists estimate there are between three and 30 million species of plants, animals, fungi, bacteria and so on, but only 1.4 million have been identified so far.

The importance of species – and the word “biodiversity” – is not well understood by the public, business or politicians. And yet biodiversity – the sum total of all living species – is what gives us air to breathe, water to drink and food to eat.

Schoolchildren learn that trees and plants produce oxygen, absorb carbon dioxide, clean water, and so on. However, what is not well understood, even by scientists, is exactly how insects, bacteria, birds, and animals interact with trees and plants to produce the ecological services we rely on, like clean air and water.

The loss of a few species in a forest or the oceans might not result in any obvious immediate changes, but scientists are beginning to connect the dots. One example of a cascade of impacts was recently documented by Canadian and U.S. marine scientists, who found that a dramatic reduction in shark populations along the U.S. east coast has resulted in population booms for rays and skates, which in turn decimated their food supply of shellfish.

The loss of the shellfish has reduced water quality and seagrass beds. The cascade doesn’t stop there, but that is as far as science has been able to track it.

Michael Totten, senior director of Conservation International, a global environmental group, offers another example.

Coastal mangrove forests provide local communities with nearly 90 percent protection from storm surges, studies show. Equally important, mangroves are the nurseries for many species of fish and play a key role in sustaining ocean fish populations, Totten said in an interview.

The more species there are in an ecosystem, the more resilient it is to change. So the combination of reduced species numbers and climate change is opening the world up for ecosystem collapse, he warned.

U.N. Secretary-General Ban Ki-moon offered a similar message for International Biodiversity Day on May 22, noting that “biodiversity is being lost at an unprecedented rate [and] this, in turn, is seriously eroding the capacity of our planet to sustain life on earth.”

“Unless we do something there will be no tigers, lions or bears left in the wild for my grandchildren,” said Stuart Pimm, a conservation ecologist at Duke University in the U.S. state of North Carolina.

“The impacts will be obvious to even the smallest child and this is a very real possibility,” Pimm told IPS.

Avoiding this grim future is challenging but far from impossible. Halting deforestation is one critical step, since it accounts for more than 20 percent of global greenhouse gas emissions. While tropical deforestation gets nearly all the attention, Canada’s 567-million-hectare boreal forest could go in a generation, he said.

Pimm, along with 1,500 other scientists, urged Canada last week to protect at least half the forest, and manage the other half much more carefully.

Not only is the boreal “the largest intact forest and wetland ecosystems remaining on earth”, it is the single largest terrestrial carbon storehouse in the world, they said in an open letter.

However, despite its enormous size, 10 percent of the forest has already been touched by mining or oil and gas operations, and another 20 percent has been clear-cut along its southern tip where biodiversity is richest, they said.

The second “easy step” to combat climate change and boost biodiversity is reforestation of tropical areas already deforested, Pimm said.

Seven million square kilometres of tropical forest have vanished in the last 50 years. About two million of that is used for crops while the remaining five million sq km are poor quality lands with a few cattle and goats on them, he said.

Turning these unproductive lands back into native forest could capture an estimated five billion metric tonnes of carbon from the atmosphere every year for 10 to 20 or more years. Reforestation is also relatively easy thing to do and has enormous benefits for biodiversity.

Global annual carbon emissions are currently eight billion tonnes.

“This could take us a long way to carbon neutrality,” Pimm said, adding that, “Things are beginning to change. The world has finally got the message on climate change – except for the White House.”

Despite accounting for a quarter of all greenhouse gas emissions, the United States has refused to ratify the Kyoto Protocol, arguing that the treaty – which mandates emissions reductions by the world’s most industrialised countries – would be too costly to enforce.