The Current Mass Extinction

“Once there were brook trout in the streams in the mountains. You could see them standing in the amber current where the white edges of their fins wimpled softly in the flow. They smelled of moss in your hand. Polished and muscular and torsional. On their backs were vermiculate patterns that were maps of the world in its becoming. Maps and mazes. Of a thing which could not be put back. Not be made right again. In the deep glens where they lived all things were older than man and they hummed of mystery.”
(Cormack McCarthy, The Road)

I have described in an earlier post a rapid (in geologic terms) loss of species and a deteriorating environment, but the possibility that we, the human race, a "weedy" species, like dandelions in our lawns, may survive. And after many generations, our progeny may have no memory, no notion, of how much is missing from the impoverished world we have bequeathed them.

But there is another possibility. One in which things happen too fast for us to adapt, and along with the vast majority of other life on earth, we follow the Passenger Pigeon into extinction.

Climate scientists today are concerned about the so-called "tipping point," the moment at which a dynamical system, such as the earth, that has been changing slowly and predictably will suddenly "flip" to a state inimical to life as we know it. With respect to the climate, this can happen as a result of certain changes inducing other changes, which in turn, induce others and reinforce the original forcing function. This is a case of positive feedback not being a good thing.

Consider sea ice, for example, an implacable force of nature that covers an area on earth about two and one half times the size of Canada. Sea ice has a very significant impact on climate change. The ice has a bright surface that reflects sunlight back into space, so areas covered by sea ice don't absorb much solar energy, and temperatures in the polar regions remain relatively cool.

As warming temperatures melt sea ice, as they are doing now, fewer bright surfaces are available to reflect sunlight back into space, more solar energy is absorbed at the surface, and temperatures rise. As sea ice melts further, more solar energy is absorbed, and more sea ice melts.This chain of events starts a cycle of warming and melting, leading to greater and greater warming and continued loss of sea ice, with predictable results; the dynamics of sea ice freezing and melting reaches a tipping point where freezing can’t keep up with melting and the sea ice disappears, removing a vital component in the earth’s homeostasis -- its ability to maintain an equilibrium.

There’s another type of “melting” that’s taking place as a result of rising global temperatures, and that’s the thawing of the permafrost covering the earth’s tundra. Tundra is located at the top of the northern hemisphere in Europe, Asia and North America. It covers 20% of the earth's surface just below the polar cap. Permafrost trapped carbon buried since the Pleistocene era. When permafrost melts, that carbon comes bubbling to the surface of lakes, and dissipating into the atmosphere as methane, a greenhouse gas 23 times more potent than carbon dioxide. And the permafrost is melting -- at five times the rate previously thought.

The rapid release of methane will accelerate the greenhouse gas trapping effect that's currently warming the earth, and that will in turn, increase the rate at which sea ice is disappearing. And that takes us back to the role of sea ice in reflecting solar energy back into the atmosphere, instead of absorbing it in the ocean. You get the drift.

Another type of tipping point occurs when a particular ecosystem sustains so much damage that it can no longer sustain itself. This is what's happening in the Amazon Rainforest.

The dense forests of the Amazon soak up more than one-quarter of the world's atmospheric carbon, making it a critically important buffer against global warming. But a warming climate combined with unchecked slash and burn clearing is bringing the rainforest to the brink of disaster.

Billions of trees died in the record drought that struck the Amazon in 2010, and agriculture, and urban development along with the road building that accompanies it are destroy billions of additional trees and the essential and fragile ground cover that makes the rainforest possible.

The Amazon is but one of ten threatened forests on the earth. If forests lose their ability to act effectively as carbon sinks, additional green house gases will contribute to accelerating global warming, which will subject the earth to further extreme droughts, loss of additional trees, and runaway climate change.

Biologists who believe the earth is experiencing its sixth mass extinction identify five primary direct drivers in addition to climate change, all are the result of human behavior: habitat loss, invasive species, pollution, over-exploitation of resources, and the factor that magnifies all the others—human overpopulation.

According to studies, at least half of all plant and animal species are likely to disappear in the wild within the next 30-40 years, including many of the most familiar and beloved large mammals: elephants, polar bears, chimpanzees, gorillas and all the great apes, all the big cats, and many, many others.

Bird species are similarly imperiled, songbird populations have declined by 50% in the last 40 years. One out of every eight species of plant life worldwide and almost one third of the plant species within the United States already face extinction.

Populations of large ocean fish have declined by 90% since the 1950s. All around the world, birds, reptiles, mammals, amphibians, fish, and invertebrates, as well as trees, flowering plants, and other flora, are all in steep decline.

As disturbing as this rapid decline of species and its attendant support for a sixth extinction event is, there's an even more disturbing, even terrifying prospect -- sudden destabilization of the earth system with imminent death and destruction across all species, including most especially, human. Is this even remotely possible? You're damn right it is.

 I'll discuss this in a future post.

The End of the Human Species

Nothing lives forever, but as the song says,

"Who wants to live forever?"

We know from the fossil record that on average between 10 and 100 species on earth become extinct every year (we're talking about every living thing, including mushrooms and Republicans). But lately, due to the impact of humans on the earth's environment, we seem to be losing something like 27,000 species per year. The following is extracted from "The Current Mass Extinction," at Evolution Library.

Humanity's main impact on the extinction rate is landscape modification, an impact greatly increased by the burgeoning human population. Now standing at 5.7 billion and growing at a rate of 1.6 percent per year, the population of the world will double in 43 years if growth continues at this pace. By draining wetlands, plowing prairies, logging forests, paving, and building, we are altering the landscape on an unprecedented scale. Some organisms do well under the conditions we've created: They tend to cope well with change, tolerate a broad range of habitats, disperse widely, and reproduce rapidly, and they can quickly crowd out more specialized local species. City pigeons, zebra mussels, rats, and kudzu and tamarisk trees -- these are examples of what biologists call "weedy" species, both animals and plants. Many weedy species will probably survive, and even thrive, in the face of the current mass extinction. But thousands of others, many never known to science, are likely to perish.

And what is the fate of our own species likely to be, if we really are in the midst of a sixth mass extinction? One possibility is that as diversity and abundance wither, the species causing it all -- Homo sapiens, the most dominant species in history -- could also be on the road to oblivion. But another possibility is that Homo sapiens, which has proved to be a very effective weedy species itself, will persist. That's the view of paleobiologist David Jablonski, who sees us as one of the survivors, "sort of picking through the rubble" of a world that has lost much of its biodiversity -- and much of its comfort. For along with that species richness, the ecosystem is likely to loose much of its ability to provide many of the valuable services that we take for granted, from cleaning and recirculating air and water, to pollinating crops and providing a source for new pharmaceuticals. And while the fossil record tells us that biodiversity has always recovered, it also tells us that the recovery will be unbearably slow in human terms -- 5 to 10 million years after the mass extinctions of the past. That's more than 200,000 generations of humankind before levels of biodiversity comparable to those we inherited might be restored.

Endangered

The Western Lowland Gorilla

In the wild, these primates are under siege. Forest loss is a twofold threat; it destroys gorilla habitat and brings hungry people who hunt gorillas for bushmeat. Farming, grazing, and expanding human settlements are also shrinking the lowland gorilla's space.

You'll noticed a common theme in my recent posts, i.e., the disappearance of the earth's species, animal and plant. Despite the nano second of human existence on the earth relative to biological time, most biologists believe we are responsible for what they call The Sixth Mass Extinction.

Daniel Simberloff, who is Professor of Environmental Studies and director of the Institute for Biological Invasions at the University of Tennessee in Knoxville, says, "I'm actually certain that we're in the midst of a mass extinction. Geologically, there have been five periods in which upwards of 20 percent of the Earth's species, in one case maybe 90 percent of the Earth's species, went extinct, and there've been about 20 or so others in which anywhere from two to 10 percent of species have gone extinct. And certainly over the last few hundred years there are enough extinctions to qualify us in the second category. There's documentary evidence, in some cases, for this. And it's an ongoing process. It's not slowing down -- if anything, it appears to be accelerating. So I think it's quite possible that we'll eventually be in a situation that qualifies as one of the great mass extinctions."

The Golden Lion Tamarin

Despite their name, these rare primates have far more in common with their monkey relatives than any feline. These interesting and beautiful animals are critically endangered, as are many of the forests in which they live. Brazil's Atlantic coastal rain forests are disappearing due to ever-expanding logging, agriculture, and industry, and unfortunately, the golden lion tamarin is in danger of vanishing with them.

Eating the Earth

“They're not creatures you can fight--they're an elemental--an 'act of God!' Ten miles long, two miles wide--ants, nothing but ants! And every single one of them a fiend from hell; before you can spit three times they'll eat a full-grown buffalo to the bones. I tell you if you don't clear out at once there'll he nothing left of you but a skeleton picked as clean as your own plantation."

Just as the voracious Army Ants in Carl Stephenson’s short story, Leiningen Versus the Ants, devour all before them, we seem a people insatiable, searching every last shore, aquifer, forest, plain, and plateau desperate for that last barrel of oil, that last board foot of lumber, that last drop of water. We stumble on imprisoned between ignorance and greed, to be delivered into the annihilation that is our god.

The earth has existed for some four and half billion years, created in some cosmic catastrophe of colliding matter and formed from toxic fumes and molten rock, its history replete with cataclysmic events of unimaginable magnitude and violence. It was 800 million to a billion years after the earth’s fiery birth before the first vestiges of primitive life were created in the form of cyanobacteria that ultimately reacted with other elements to transform the earth into an habitable planet. And along came man. But not for billions of years.

Homo sapiens, or “modern man” emerged only about 120,000 years ago. That makes man’s time upon the earth clock about 2 seconds out of 24 -- a blip of miniscule proportion. But, like a bacteria, we have morphed and multiplied many times over.

At the dawn of the first millennium A.D., the world’s population was around 300 million people. Growth into the second millennium was modest, but by the time of the American Revolutionary War, the population of humans on earth had grown to over a billion, despite the ravages of the Black Plague in the thirteen hundreds. Human population is today, some 230 years later, over 6.7 billion and growing exponentially. By 2050, 42 years from now, the number of people on earth will increase by over 40%, to 9.5 billion.

It is unreasonable to expect that a presence of such magnitude and rapacious appetite would not change the earth upon which it dwells. According to some geologists, humans have so drastically altered the earth that the Holocene epoch, which started 10,000 years ago, has ended and we have entered a new epoch - the Anthropocene.

Early humans, hunter-gathers -- had little impact on the planet. But with the advent of technology, the human footprint grew disproportionately. Man is dominant on the earth, and like the cyanobacteria of eons ago, is reshaping the earth dramatically, but not in ways that make it more habitable. We are making the world hotter, drier, dirtier, and biologically less diverse. We have destroyed over half of the world's wetlands and original forests, polluted rivers and the ocean, and poisoned the land. We cause the extinction of an average of 100 species per day. Sociobiologist E. O. Wilson predicts that if we don’t slow our consumption of natural resources, we’ll extinguish half the species of plants and animals by the end of the 21st century.

According to Lord Robert May, Professor of Zoology at Oxford University, and winner of the Royal Society’s Copley medal, the world’s oldest prize for scientific achievement, "We stand on the brink of a global extinction event -- the sixth episode in the history of the Earth." The most recent extinction event, approximately 65 million years ago, closed the Cretaceous period and ended the reign of dinosaurs. "The difference is that the current global extinction event is being caused by the actions of a single dominant species rather than a 'natural' event," said Lord May. We are part of the Earth's great fauna, but we are also its greatest menace.

The human species has become a plague on the face of the earth.

And the Lord said, I will destroy man whom I have created from the face of the earth...for it repenteth me that I have made him.