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Earthday Lament, ‘The Sixth Extinction’
http://www.biologicaldiversity.org/programs/biodiversity/elements_of_biodiversity/extinction_crisis/
THE EXTINCTION CRISIS
It’s frightening but true: Our planet is now in the midst of its sixth mass extinction of plants and animals — the sixth wave of extinctions in the past half-billion years. We’re currently experiencing the worst spate of species die-offs since the loss of the dinosaurs 65 million years ago. Although extinction is a natural phenomenon, it occurs at a natural “background” rate of about one to five species per year. Scientists estimate we’re now losing species at 1,000 to 10,000 times the background rate, with literally dozens going extinct every day [1]. It could be a scary future indeed, with as many as 30 to 50 percent of all species possibly heading toward extinction by mid-century [2].
Unlike past mass extinctions, caused by events like asteroid strikes, volcanic eruptions, and natural climate shifts, the current crisis is almost entirely caused by us — humans. In fact, 99 percent of currently threatened species are at risk from human activities, primarily those driving habitat loss, introduction of exotic species, and global warming [3]. Because the rate of change in our biosphere is increasing, and because every species’ extinction potentially leads to the extinction of others bound to that species in a complex ecological web, numbers of extinctions are likely to snowball in the coming decades as ecosystems unravel.
Species diversity ensures ecosystem resilience, giving ecological communities the scope they need to withstand stress. Thus while conservationists often justifiably focus their efforts on species-rich ecosystems like rainforests and coral reefs — which have a lot to lose — a comprehensive strategy for saving biodiversity must also include habitat types with fewer species, like grasslands, tundra, and polar seas — for which any loss could be irreversibly devastating. And while much concern over extinction focuses on globally lost species, most of biodiversity’s benefits take place at a local level, and conserving local populations is the only way to ensure genetic diversity critical for a species’ long-term survival.
In the past 500 years, we know of approximately 1,000 species that have gone extinct, from the woodland bison of West Virginia and Arizona’s Merriam’s elk to the Rocky Mountain grasshopper, passenger pigeon and Puerto Rico’s Culebra parrot — but this doesn’t account for thousands of species that disappeared before scientists had a chance to describe them [4]. Nobody really knows how many species are in danger of becoming extinct. Noted conservation scientist David Wilcove estimates that there are 14,000 to 35,000 endangered species in the United States, which is 7 to 18 percent of U.S. flora and fauna. The IUCN has assessed roughly 3 percent of described species and identified 16,928 species worldwide as being threatened with extinction, or roughly 38 percent of those assessed. In its latest four-year endangered species assessment, the IUCN reports that the world won’t meet a goal of reversing the extinction trend toward species depletion by 2010 [5].
What’s clear is that many thousands of species are at risk of disappearing forever in the coming decades.
<snip>
It’s frightening but true: Our planet is now in the midst of its sixth mass extinction of plants and animals — the sixth wave of extinctions in the past half-billion years. We’re currently experiencing the worst spate of species die-offs since the loss of the dinosaurs 65 million years ago. Although extinction is a natural phenomenon, it occurs at a natural “background” rate of about one to five species per year. Scientists estimate we’re now losing species at 1,000 to 10,000 times the background rate, with literally dozens going extinct every day [1]. It could be a scary future indeed, with as many as 30 to 50 percent of all species possibly heading toward extinction by mid-century [2].
Unlike past mass extinctions, caused by events like asteroid strikes, volcanic eruptions, and natural climate shifts, the current crisis is almost entirely caused by us — humans. In fact, 99 percent of currently threatened species are at risk from human activities, primarily those driving habitat loss, introduction of exotic species, and global warming [3]. Because the rate of change in our biosphere is increasing, and because every species’ extinction potentially leads to the extinction of others bound to that species in a complex ecological web, numbers of extinctions are likely to snowball in the coming decades as ecosystems unravel.
Species diversity ensures ecosystem resilience, giving ecological communities the scope they need to withstand stress. Thus while conservationists often justifiably focus their efforts on species-rich ecosystems like rainforests and coral reefs — which have a lot to lose — a comprehensive strategy for saving biodiversity must also include habitat types with fewer species, like grasslands, tundra, and polar seas — for which any loss could be irreversibly devastating. And while much concern over extinction focuses on globally lost species, most of biodiversity’s benefits take place at a local level, and conserving local populations is the only way to ensure genetic diversity critical for a species’ long-term survival.
In the past 500 years, we know of approximately 1,000 species that have gone extinct, from the woodland bison of West Virginia and Arizona’s Merriam’s elk to the Rocky Mountain grasshopper, passenger pigeon and Puerto Rico’s Culebra parrot — but this doesn’t account for thousands of species that disappeared before scientists had a chance to describe them [4]. Nobody really knows how many species are in danger of becoming extinct. Noted conservation scientist David Wilcove estimates that there are 14,000 to 35,000 endangered species in the United States, which is 7 to 18 percent of U.S. flora and fauna. The IUCN has assessed roughly 3 percent of described species and identified 16,928 species worldwide as being threatened with extinction, or roughly 38 percent of those assessed. In its latest four-year endangered species assessment, the IUCN reports that the world won’t meet a goal of reversing the extinction trend toward species depletion by 2010 [5].
What’s clear is that many thousands of species are at risk of disappearing forever in the coming decades.
<snip>
http://www.nytimes.com/2014/02/16/books/review/the-sixth-extinction-by-elizabeth-kolbert.html?hpw&rref=books&_r=0
By AL GORE FEB. 10, 2014
Over the past decade, Elizabeth Kolbert has established herself as one of our very best science writers. She has developed a distinctive and eloquent voice of conscience on issues arising from the extraordinary assault on the ecosphere, and those who have enjoyed her previous works like “Field Notes From a Catastrophe” will not be disappointed by her powerful new book, “The Sixth Extinction: An Unnatural History.”
Kolbert, a staff writer at The New Yorker, reports from the front lines of the violent collision between civilization and our planet’s
ecosystem: the Andes, the Amazon rain forest, the Great Barrier Reef — and her backyard. In lucid prose, she examines the role of
man-made climate change in causing what biologists call the sixth mass extinction — the current spasm of plant and animal loss that threatens to eliminate 20 to 50 percent of all living species on earth within this century.
Extinction is a relatively new idea in the scientific community. Well into the 18th century, people found it impossible to accept the idea that species had once lived on earth but had been subsequently lost. Scientists simply could not envision a planetary force powerful enough to wipe out forms of life that were common in prior ages.
In the same way, and for many of the same reasons, many today find it inconceivable that we could possibly be responsible for destroying the integrity of our planet’s ecology. There are psychological barriers to even imagining that what we love so much could be lost — could be destroyed forever. As a result, many of us refuse to contemplate it. Like an audience entertained by a magician, we allow ourselves to be deceived by those with a stake in persuading us to ignore reality.
For example, we continue to use the world’s atmosphere as an open sewer for the daily dumping of more than 90 million tons of gaseous waste. If trends continue, the global temperature will keep rising, triggering “world-altering events,” Kolbert writes. According to a conservative and unchallenged calculation by the climatologist James Hansen, the man-made pollution already in the atmosphere traps as much extra heat energy every 24 hours as would be released by the explosion of 400,000 Hiroshima-class nuclear bombs. The resulting rapid warming of both the atmosphere and the ocean, which Kolbert notes has absorbed about one-third of the carbon dioxide we have produced, is wreaking havoc on earth’s delicately balanced ecosystems. It threatens both the web of living species with which we share the planet and the future viability of civilization. “By disrupting these systems,” Kolbert writes, “we’re putting our own survival in danger.”
..more..
By AL GORE FEB. 10, 2014
Over the past decade, Elizabeth Kolbert has established herself as one of our very best science writers. She has developed a distinctive and eloquent voice of conscience on issues arising from the extraordinary assault on the ecosphere, and those who have enjoyed her previous works like “Field Notes From a Catastrophe” will not be disappointed by her powerful new book, “The Sixth Extinction: An Unnatural History.”
Kolbert, a staff writer at The New Yorker, reports from the front lines of the violent collision between civilization and our planet’s
ecosystem: the Andes, the Amazon rain forest, the Great Barrier Reef — and her backyard. In lucid prose, she examines the role of
man-made climate change in causing what biologists call the sixth mass extinction — the current spasm of plant and animal loss that threatens to eliminate 20 to 50 percent of all living species on earth within this century.
Extinction is a relatively new idea in the scientific community. Well into the 18th century, people found it impossible to accept the idea that species had once lived on earth but had been subsequently lost. Scientists simply could not envision a planetary force powerful enough to wipe out forms of life that were common in prior ages.
In the same way, and for many of the same reasons, many today find it inconceivable that we could possibly be responsible for destroying the integrity of our planet’s ecology. There are psychological barriers to even imagining that what we love so much could be lost — could be destroyed forever. As a result, many of us refuse to contemplate it. Like an audience entertained by a magician, we allow ourselves to be deceived by those with a stake in persuading us to ignore reality.
For example, we continue to use the world’s atmosphere as an open sewer for the daily dumping of more than 90 million tons of gaseous waste. If trends continue, the global temperature will keep rising, triggering “world-altering events,” Kolbert writes. According to a conservative and unchallenged calculation by the climatologist James Hansen, the man-made pollution already in the atmosphere traps as much extra heat energy every 24 hours as would be released by the explosion of 400,000 Hiroshima-class nuclear bombs. The resulting rapid warming of both the atmosphere and the ocean, which Kolbert notes has absorbed about one-third of the carbon dioxide we have produced, is wreaking havoc on earth’s delicately balanced ecosystems. It threatens both the web of living species with which we share the planet and the future viability of civilization. “By disrupting these systems,” Kolbert writes, “we’re putting our own survival in danger.”
..more..
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