|
"Life would be easier if we didn't have the kind of population growth rates that we have at the moment," Mr. Steiner said, "But to force people to stop having children would be simplistic answer. The more realistic, ethical and practical issue is to accelerate human well being and make more rational use of the resources we have on this planet."
Mr. Steiner said parts of Africa could reach an environmental tipping point if changing rainfall patterns stemming from climate change turned semi-arid zones into arid zones and made the agriculture that sustains millions of people much harder.
Mr. Steiner said another tipping point could occur in India and China if Himalayan glaciers shrink so much that they no longer supply adequate amounts of water to populations in those countries.
He also warned of a global collapse of all species being fished by 2050, if fishing around the world continued at its present pace.
The report said 250 percent more fish are being caught than the oceans can produce in a sustainable manner, and that the level of global fish stocks classed as collapsed had roughly doubled to 30 percent over the past 20 years.
The report said that current changes in biodiversity were the fastest in human history, with species becoming extinct a hundred times faster than the rate in the fossil record. It said 12 percent of birds are threatened with extinction; for mammals the figure is 23 percent and for amphibians it is more than 30 percent.
"Scientists now refer to a sixth major extinction crisis that's under way," Steiner said.
The first mass extinction, about 440 million years ago, and the four succeeding extinctions were the result of physical shocks to the planet like volcanic eruptions and plate tectonic shifts.
The report said that annual emissions of CO2 from fossil fuels have risen by about one-third since 1987 and that the threat from climate change now was so urgent that only very large cuts in greenhouse gases of 60 to 80 percent could stop irreversible change.
The effects of global warming, like the melting ice in the Arctic are "accelerating at a pace that goes beyond the scenarios and models we've been using," Steiner said.
Climate change, however, was an issue that gained huge momentum over the past year, with governments, industries and citizens increasingly seeking solutions to the problem, Steiner said. The recent award of the Nobel Peace Prize to the Intergovernmental Panel on Climate Change and to former Vice President Al Gore was a sign of widespread scientific consensus that climate change is under way, he said.
Steiner called for an accelerated effort on a far wider range of environmental issues to build the same sense of urgency as shown on climate change over the past year to address the worsening situations of biodiversity, land degradation, fisheries and freshwater.
Many biologists and climate scientists have concluded that human activities have become a dominant influence on the planet's climate and ecosystems. But there is still a range of views on whether this could result in a catastrophic unraveling of natural resources as the human population heads toward nine billion by midcentury, or more of a steady diminution in diversity.
|
|
