Evidence Suggests World
On Brink Of Another
Mass Extinction
By Peter P. (
From: Earth-Changes Weekly
As the twentieth-century comes to a close, a recent number of studies looking at a wide range of life suggest one irrevocable conclusion when viewed in tandem: The world may be on the brink of a sixth mass extinction.
Scientists have used fossil records in efforts to piece together the development and death of many long-ago species, but cutting across this tumultuous evolution of life is a succession of mass disappearances - at least five globally in the past 500 million years - followed by rebirth.
The causal agent of past mass extinctions varies. It is theorized that one such extinction, some 250 million years ago, was caused by a volcanic outpouring of super-heated rock that rose from the Earth's lower mantle, some 1,800 miles deep, and broke through the crust near present-day Siberia, resulting in a vast flood of lava up to a million times the material spewed out by an eruption such as that of Mount St. Helens. In fact, the one million cubic kilometers of molten volcanic rock that is believed to have broken through the surface would've been enough lava to cover the entire Earth to a depth of 10 feet [1]. The most recent mass extinction of some 65 million years ago, the popular theory goes, occurred when an asteroid slammed into the Yucatan area of Mexico. The dinosaurs, and most everything else living on the planet at the time, perished in the disastrous ecological aftermath.
While such past worldwide extinctions have been linked to sudden, catastrophic events, the most recent signs pointing to a possible "sixth mass extinction" suggest the following - while the end result would be just as catastrophic, the cause is much more subtle.
From the land to the sea, and the creatures both great and small once thriving upon and within, an ever-increasing number of die-offs are apparently occurring.
Upon the land, close to one out of every eight plants in the world faces possible extinction due to a loss of habitat and competition from the introduction of non-native plants. A 20-year study, by the World Conservation Union, showed some 12.5% of the world's seed-producing plants and ferns - or nearly 34,000 species in all - to be endangered. That figure rose to 29% (of plants at risk) in the United States alone. In the rose family, 14% of species were endangered. In the lily and iris families, a full 32% were in trouble. Overall, of 270,000 species of vascular plant (conifers, ferns and flowering plants - but NOT mosses, lichens, algae & fungi) total, some 33,798 species in 200 countries were found to be threatened[2].
The world's trees don't fare much better these days. Some 10% of tree species are at risk of extinction because of felling, forest fires and poor forest management, a three-year project by the World Conservation Monitoring Center recently revealed. Specifically, more than 8,753 of the globe's 80,000 to 100,000 tree species are in danger of extinction[3].
As the trees go, so does the forest. More than half of the world's original forest cover has been destroyed, and that remaining is mostly degraded. Only 22% is considered "frontier" forest, which is defined (by the World Resources Institute) as "large intact natural forest ecosystems capable of providing a safe habitat for all its indigenous species."
Tropical rainforests are disappearing at an alarming rate. If present rates of deforestation continues, some experts estimate all such forests will be cleared in about 177 years. Already, Latin America has lost some 37% of its tropical forests, Asia has lost 42% and even Africa has 52% less [4]. A mere 3% of the world's remaining frontier forests are in the temperate zone. Originally covering 0.2% of the Earth's land area, more than half of the planet's temperate rainforests have already been destroyed. Those remaining are mainly located in two regions - southern Chile, and an area extending from northern California to British Columbia and southeast Alaska. A small percentage is spread throughout the southern hemisphere[5].
Animal species are also in decline. According to a World Conservation Union study, about one in four vertebrate species surveyed up to this point is in serious trouble. According to the study's estimates, some 25% of mammals and amphibian species, 11% of birds, 20% of reptiles, and 34% of fish species surveyed so far are threatened with extinction. Another 5% to 14% of species in these groups are nearing "threatened status" [6]. Scientists estimate that extinction rates are now 100 to 1000 times greater than normal - and rising. Either declining sharply in numbers or limited to very small populations, species face pressure from land clearance, excessive hunting or fishing, and the help humanity - both intentionally and unintentionally - gives to invasive species, further threatening native fauna.
As people use more water, less is left for vital ecosystems on which humans and other species depend. Globally, more than 20% of all freshwater fish species are endangered or vulnerable, or recently have become extinct. A growing number of saltwater fish are also facing extinction, due in part to overfishing.
Even human birthrates, in the industrialized world at least, are in a rapid, sustained decline. Due primarily to prosperity in the developed world, millions of women are staying in school longer, working harder and marrying later -- and having fewer children than ever before.
Never before, except in times of war, plague and economic depression, have birthrates fallen so low, for so long. In Europe, there is not one country where people are now having enough children to replace themselves when they die. Even in the U.S., the birth average of slightly below 2.1 children per woman, the number needed to keep the population from beginning to shrink. And while populations in Africa, India and Asia do continue to sustainably grow, since 1965 the birthrate has been cut in half, a bigger drop than in the two previous centuries[7].
Across the globe, species of all kinds are in decline. Many as a result, directly or indirectly, of the long-reaching hand of humankind. So, are we on the brink of a "sixth mass extinction"? According to a recent survey, of 400 biologists, some 7 out of 10 answered a resounding "yes". They predicted that up to one-fifth of all living species could disappear within 30 years [8]. Nearly all surveyed attributed the losses to human activity.
[1] "Earth Extinctions Linked to Lower Mantle Eruptions" A. Basuo, R. Hannigan & S. Jacobsen (University of Rochester/Harvard University), 'Geophysical Research Letters', July 1998.
[2] "Red List of Threatened Plants" World Conservation Union, April 1998.
[3] "World List of Threatened Trees", World Conservation Monitoring Center, August 1998.
[4] International Wildlife Education & Conservation Factsheet
[5] "Forests in Trouble: Review of the Status of Temperate Forests Worldwide" N. Dudley, WWF, 1992.
[6] Worldwatch Institute, World Conservation Union study "Higher Animals Facing Major Declines" May 30, 1998
[7] "World put out fuse on population bomb" New York Times, July 19 1998.
[8] "Mass Extinction Underway", Discovery Online, April 20 1998