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For the past two weeks we've digressed from the topic of species extinction, which developed from a discussion of global warming, which arose from the fundamental purpose of this column, which is to explore the wide-ranging issues of environmental sustainability and responsibility as they apply, not only on a global basis, but also to our local community of Downey.
Hence, for the past two weeks in this space, we first announced and then recapped a local community bike ride. That ride is projected to become a regular event, which will not only continue to raise bicycle awareness in the Downey area, but also continue in its small, gentle way to help our environment by getting folks out of cars and exercising on their bikes, where you can hear the sound of nature around you and feel the breeze in your face and the sun on your back.
But, until we ride again, let's return to our discussion of species extinction, where, depending on whom you talk to, the polar bear, or the spotted owl, or the timber wolf, or the Delta smelt, is the poster child for species extinction. To put these concerns in their broadest perspective, scientific estimates gauge the overall extinction rate at 99.9%. (A typical species, by the way, becomes extinct within 10 million years of its first appearance.)
The International Union for Conservation of Nature (IUCN), which, as we've described previously, is the world's "oldest and largest global environmental organization," compiling its research with the voluntary cooperation of some 11,000 scientists and experts, estimates the number of current species at 1,700,000. Restating the obvious, that 1.7 million is estimated to be one tenth of one percent of all the species that ever existed on earth.
The IUCN Red List of Endangered Species further categorizes these extant species: about a million of them are insects, catalogued along with about 1.3 million invertebrates. Some 300,000 are plants, and about 50,000 are fungi, of which 31,496 species of mushroom have been inventoried. Likewise, the numbers are quite specific for vertebrates: 10,064 species of birds and 5,501 species of mammals.
IUCN has been estimating the number of threatened species in each category since 1996. Its current estimates include 100% of all bird and mammal species catalogued. According to its most recent research, 1,140 species of mammals are classified as "threatened" in 2012. IUCN's 3-tiered estimate of the percentage of all mammals threatened includes an upper level of 36%.
To think that over a third of our mammalian cousins might be threatened with extinction is a sobering thought, especially if we begin to wonder whether humans could be next. That's certainly not a problem, at least not yet, because the global population of homo sapiens is expected to peak in about 2050 at 9 billion. (We reached 7 billion last Halloween.)
By contrast, the current number of polar bears is estimated to be only 20,000-25,000. The Eastern timber wolf (or gray wolf) is already extinct, and the global population of wolves is estimated at about 200,000, 10% of their numbers in earlier times.
Furthermore, the modern rate of extinction is estimated to be 100 to 1,000 times faster than historical extinction rates, and humankind, the dominant species of the epoch, is known to be a big contributor to this extinction pattern, now being studied under the term "holocene extinction."
What is happening out there, and what should we be doing about it? We'll examine those questions next time.
Meanwhile, how about let's all go out for a bicycle ride!
Published: September 6, 2012 - Volume 11 - Issue 21