Humans are damaging the planet at an unprecedented rate and raising risks of abrupt collapses that could worsen the spread of disease, deforestation and “dead zones” in the seas, according to a report released Wednesday and billed as the most comprehensive look at Earth's vital signs.
The study, by 1,360 experts in 95 nations, said a rising human population had polluted or overexploited two thirds of the ecological systems on which life depends, ranging from clean air to fresh water, in the past 50 years.
“At the heart of this assessment is a stark warning,” wrote the board members of the Millennium Ecosystem Assessment. “Human activity is putting such strain on the natural functions of Earth that the ability of the planet’s ecosystems to sustain future generations can no longer be taken for granted.”
“Over the past 50 years, humans have changed ecosystems more rapidly and extensively than in any comparable time in human history, largely to meet rapidly growing demands for food, fresh water, timber, fiber and fuel,” the report said.
“This has resulted in a substantial and largely irreversible loss in the diversity of life on Earth,” it added. More land was changed to cropland since 1945, for instance, than in the 18th and 19th centuries combined.
Next 50 years could be 'significantly worse'
“The harmful consequences of this degradation could grow significantly worse in the next 50 years,” it said. The report was compiled by experts from U.N. agencies and other international organizations such as the World Bank.
U.N. Secretary-General Kofi Annan said the study “shows how human activities are causing environmental damage on a massive scale throughout the world, and how biodiversity — the very basis for life on Earth — is declining at an alarming rate.”
The report said there was evidence that strains on nature could trigger abrupt changes like the collapse of cod fisheries off Newfoundland in Canada in 1992 after years of overfishing. The collapse put tens of thousands of people out of work and cost $2 billion in income support and retraining.
Future changes could bring sudden outbreaks of disease. Warming of the Great Lakes in Africa due to climate change, for instance, could create conditions for a spread of cholera.
And a buildup of nitrogen from fertilizers washed off farmland into seas could spur abrupt blooms of algae that choke fish or create oxygen-depleted “dead zones” along coasts.
Nitrogen fertilizers were first made in 1913, the report noted, yet more than half has been used since 1985. That, in turn, is responsible for "a substantial and largely irreversible loss in diversity of life on Earth, with some 10 to 30 percent of the mammal, bird and amphibian species currently threatened with extinction."
It said deforestation often led to less rainfall. And at some point, lack of rain could suddenly undermine growing conditions for remaining forests in a region.
The report said that in 100 years global warming, which many scientists tie to the burning of fossil fuels in cars, factories and power plants — might take over as the main source of damage. The report mainly looks at other, shorter-term risks.
Estimating nature's value
The survey also estimated that many ecosystems were worth more if used in a way that maintains them for future generations.
A wetland in Canada was worth $6,000 a hectare (2.47 acres), as a habitat for animals and plants, a filter for pollution, a store for water and a site for human recreation, against $2,000 if converted to farmland, it said. A Thai mangrove was worth $1,000 a hectare in coastal protection against $200 as a shrimp farm.
“Ecosystems and the services they provide are financially significant and ... to degrade and damage them is tantamount to economic suicide,” said Klaus Toepfer, head of the U.N. Environment Program.
"I am not one of those who believe everything in this world should be boiled down to dollars and cents," he added. "But these estimated values are a good start and are a useful and additional reason to care for and respect natural capital alongside financial and human capital."
The study urged changes in consumption, better education, new technology and higher prices for exploiting ecosystems.
“Governments should recognize that natural services have costs,” A.H. Zakri of the U.N. University and a co-chair of the report told Reuters. “Protection of natural services is unlikely to be a priority for those who see them as free and limitless.”
The full report and additional background are online at www.millenniumassessment.org.
Reuters contributed to this report.