Living Planet Report: Nature's credit overdrawn

Earth's resources are being used faster than they can be replaced, according to a new report, which claims humanity's impact on the planet has more than tripled since 1961. "Living Planet Report 2006," released on Oct. 24 by the global conservation group World Wildlife Fund and the Global Footprint Network, says that by 2050 humanity will demand twice as much as the planet can supply. Humanity is living off its ecological credit card, said Dr. Mathis Wackernagel, executive director of Global Footprint Network, an Oakland, CA, group working internationally to make ecological limits central to decision-making. While this can be done for a short while, overshoot ultimately leads to liquidation of the planet's ecological assets, and the depletion of resources, such as the forests, oceans and agricultural land upon which our economy depends. Overshoot describes the gap between what humanity uses and how long the Earth takes to replace it. It is integral to the Ecological Footprint, a measure of human demand on ecosystems and one of two indicators used in the report. The other is the Living Planet Index, which reflects the health of those ecosystems. The report describes the changing state of global biodiversity and the pressures of human consumption on natural resources. It calculates that in 2003, humanity's ecological footprint was 25 percent larger than the planet's capacity to produce these resources–meaning that it took about one year and three months for the Earth to regenerate what we used in a single year. That figure is projected to rise to 30 percent this year and to 100 percent in 2050. The fastest growing part of that footprint is fossil fuel use and carbon dioxide emissions, increasing more than nine-fold from 1961 to 2003. The report also highlights a rapid and continuing loss of biodiversity–populations of vertebrate species have declined by about one third since 1970, confirming previous trends. "We have been exceeding the Earth's ability to support our lifestyles for the past 20 years, and we need to stop," said James Leape, director general of WWF International. "We must balance our consumption with the natural world's capacity to regenerate and absorb our wastes. If we do not, we risk irreversible damage." The report's Living Planet Index tracked trends from 1970 to 2003 in over 3,600 populations of more than 1,300 vertebrate species–fish, amphibians, reptiles, birds and mammals–from around the world. Overall, the index found that vertebrate species populations have declined by about 30 percent between 1970 and 2003, but within that trend were marked differences between temperate and tropical species. Tropical species populations declined by around 55 percent on average from 1970 to 2003, while temperate species populations, which would have shown marked declines prior to 1970, have shown little overall change since. The report suggests that this is because in temperate ecosystems, the conversion of natural habitat to farmland largely took place before 1950, when populations of temperate species are likely to have declined before stabilizing. The more dramatic decline of tropical species is mirrored by the conversion of natural habitat to cropland or pasture between 1950 and 1990. The tropical forests of Southeast Asia have seen the fastest conversion in the last two decades. Among marine species, the report found a greater than 25 percent decline on average across the Pacific, Atlantic, Indian and Southern oceans. While trends have remained relatively stable in the Pacific and Atlantic, there were "dramatic declines in the Indian/Southeast Asian and Southern oceans." Those declines can be partly attributed to the plight of the world's mangroves. Mangroves are saltwater tolerant, inter-tidal forests growing along tropical shorelines that provide nurseries for 85 percent of commercial fish species in the tropics. They also protect shorelines from damaging storms, prevent erosion by stabilizing sediments with their tangled root systems and help maintain water quality by filtering pollutants and trapping sediments originating from land. The report found that mangroves are being degraded or destroyed at about twice the rate of tropical forests. It's estimated that more than a third of the global area of mangrove forest was lost between 1990 and 2000. More than a quarter of Asia's mangrove cover was lost in the 10 year period preceding 2000. In South America, almost half of all mangroves were lost over the same period. Fish populations are dwindling across the world's oceans. "Overall increases in the populations of sea birds and some mammal species in the Atlantic and Pacific oceans since 1970, mask a decline in many fish species, especially those of economic importance such as cod and tuna, which are decreasing as a result of overfishing, as well as turtles and other species that are caught as by-catch," said the report. The freshwater index examined average trends in 344 species–287 in temperate zones and 51 in tropical zones. Among freshwater species the report found a population decline of about 30 percent between 1970 and 2003, but there were marked differences within that trend. Populations of freshwater birds remain relatively stable, while other freshwater species, such as the American crocodile, African bullfrog and box turtle, have declined on average by about 50 percent over the same period. The report cites habitat destruction, overfishing, invasive species, pollution and the disruption of river systems as the main causes for the decline of freshwater animals. Rivers altered or dammed for industrial and domestic use, irrigation and hydroelectric power have fragmented more than half of the world's large river systems, said the report, affecting 83 percent of their total annual flow. The report's study of humanity's ecological footprint breaks down how individual components each contribute to our overall demand on the planet. The footprint of a country includes: cropland, grazing land, forest and fishing grounds required to produce the food, fiber and timber it consumes, to absorb the wastes emitted in generating the energy it uses and to provide space for its infrastructure. The United Arab Emirates has the largest ecological footprint per person by country, the report finds, followed by the United States, Finland, Canada, Kuwait, Australia, Estonia, Sweden, New Zealand, Norway and Denmark. The report warns: "We cannot remain in overshoot much longer without depleting the planet's biological resources and interfering with its long-term ability to renew them." Wackernagel said the 44-page report raises a simple question: How can we live well and live within the means of one planet? This is the main research question of the 21st century. "We know where to start," said Leape. "The biggest contributor to our footprint is the way in which we generate and use energy. The Living Planet Report indicates that our reliance on fossil fuels to meet our energy needs continues to grow and that climate-changing emissions now make up 48 percent of our global footprint. "The good news is that this can be done," Leape offered. "We already have technologies that can lighten our footprint, including many that can significantly reduce climate-threatening carbon dioxide emissions."