"In one sense we know much less about Earth than we do about Mars. The vast majority of life forms on our planet are still undiscovered, and their significance for our own species remains unknown. This gap in our knowledge is a serious matter: we will never completely understand and preserve the living world around us at our present level of ignorance.
"If all mankind were to disappear, the world would regenerate back to the rich state of equilibrium that existed ten thousand years ago. If insects were to vanish, the environment would collapse into chaos."
Edward O. Wilson, The world's leading authority on Biodiversity, Emeritus Professor of Biology at Harvard and author of "The Creation: An Appeal to Save Life on Earth."
There is little doubt left in the minds of professional biologists that Earth is currently faced with a mounting loss of species that threatens to rival the five great mass extinctions of the geological past, the most devasting being the Third major Extinction (c. 245 mya), the Permian, where 54% of the planet's species families lost. As long ago as 1993, Harvard biologist E.O. Wilson estimated that Earth is currently losing something on the order of 30,000 species per year -- which breaks down to the even more daunting statistic of some three species per hour. Some biologists have begun to feel that this biodiversity crisis -- this "Sixth Extinction" -- is even more severe, and more imminent, than Wilson had supposed.
With the human population expected to reach 9-10 billion by the end of the century and the planet in the middle of its sixth mass extinction — this time due to human activity — the next few years are critical in conserving Earth’s precious biodiversity. The cause of the Sixth Extinction, Homo sapiens, means we can continue on the path to our own extinction, or, preferably, we modify our behavior toward the global ecosystem of which we are still very much a part.
At a casual glance, the physically caused extinction events of the past might seem to have little or nothing to tell us about the current Sixth Extinction, which is a human-caused event. For there is little doubt that humans are the direct cause of ecosystem stress and species destruction in the modern world through transformation of the landscape, overexploitation of species, pollution, and the introduction of alien species
The Sixth Extinction can be characterized as the first recorded global extinction event that has a biotic, rather than a physical, cause, due to massive asteroid impact, volcanic eruptions. Yet, looking deeper, human impact on the planet is a similar to the Cretaceous cometary collision. Sixty-five million years ago that extraterrestrial impact -- through its sheer explosive power, followed immediately by its injections of so much debris into the upper reaches of the atmosphere that global temperatures plummeted and, most critically, photosynthesis was severely inhibited -- wreaked havoc on the living systems of Earth, which is precisely what we are doing to the planet right now.
Phase two of the Sixth Extinction began around 10,000 years ago with
the invention of agriculture-perhaps first in the Natufian culture of
the Middle East. Agriculture appears to have been invented several
different times in various different places, and has, in the
intervening years, spread around the entire globe.
Agriculture, which began around 10,000 years ago in the Natufian culture of the Middle East, is a major engine driving the Sixth Extinction, represents the single most profound ecological change in the entire 3.5 billion-year history of life. With its invention humans did not have to interact with other species for survival, and so could manipulate other species for their own use nor did humans have to adhere to the ecosystem's carrying capacity, and so could overpopulate
Homo sapiens became the first species to stop living inside local ecosystems. All other species, including our ancestral hominid ancestors, all pre-agricultural humans, and remnant hunter-gatherer societies still extant exist as semi-isolated populations playing specific roles (i.e., have "niches") in local ecosystems. This is not so with post-agricultural revolution humans, who in effect have stepped outside local ecosystems. Indeed, to develop agriculture is essentially to declare war on ecosystems - converting land to produce one or two food crops, with all other native plant species all now classified as unwanted "weeds" -- and all but a few domesticated species of animals now considered as pests.
Yet, upon further reflection, human impact on the planet is a direct analogue of the Cretaceous cometary collision. Sixty-five million years ago that extraterrestrial impact -- through its sheer explosive power, followed immediately by its injections of so much debris into the upper reaches of the atmosphere that global temperatures plummeted and, most critically, photosynthesis was severely inhibited -- wreaked havoc on the living systems of Earth. That is precisely what human beings are doing to the planet right now: humans are causing vast physical changes on the planet.
"The comparison I make between these big extinction events, prehistoric meteorite-caused or natural event-caused extinctions and the present one," says E.O. Wilson, "is parallel to the difference between a heart attack and cancer. We understand that what we are doing is a slow but insidious, and only can be seen when you lay it out over the whole world over a period of decades. The hopeful thing about it is that this cancer can be treated. A lot of damage has been done, and it can be dangerous to us if we really just go on until half the species of organisms are extinct forever. Or we can halt the hemorrhaging.
"In terms of scale, it’s hard to put a figure on it," Wilson adds: "We’re in a pronounced early stage of an extinction event that would probably be, by the end of this century if human activities continue unabated, right up to the Cretaceous level. We’re part way there. Whether you can say its 10 percent there or 25 percent there, a lot of it depends on the organisms you’re talking about. One estimate has it that, particularly when you throw in the mass extinction of the Pacific Island birds, which are the most vulnerable on Earth, something like 20 percent of bird species has been extinguished by human activities."
Biocide is occurring at an alarming rate. Experts say that at least half of the world’s current species will be completely gone by the end of the century. Wild plant-life is also disappearing. Most biologists say that we are in the midst of an anthropogenic mass extinction. Numerous scientific studies confirm that this phenomenon is real and happening right now. Should anyone really care? Will it impact individuals on a personal level? Scientists say, “Yes!”
Critics argue that species disappear and new ones emerge all the time. That’s true, if you’re speaking in terms of millennia. Scientists acknowledge that species disappear at an estimated rate of one species per million per year, with new species replacing the lost ones at around the same rate. Recently humans have accelerated the extinction rate to where several entire species are annihilated every single day. The death toll artificially caused by humans is mind-boggling. Nature will take millions of years to repair what we destroy in just a few decades.
A recent analysis, published in the journal Nature, shows that it takes 10 million years before biological diversity even begins to approach what existed before a die-off. Over 10,000 scientists in the World Conservation Union have compiled data showing that currently 51 per cent of known reptiles, 52 per cent of known insects, and 73 per cent of known flowering plants are in danger along with many mammals, birds and amphibians. It is likely that some species will become extinct before they are even discovered, before any medicinal use or other important features can be assessed. The cliché movie plot where the cure for cancer is about to be annihilated is more real than anyone would like to imagine.
Research done by the American Museum of Natural History found that the vast majority of biologists believe that mass extinction poses a colossal threat to human existence, and is even more serious of an environmental problem than one of its contributors- global warming. The research also found that the average person woefully underestimates the dangers of mass extinction. Powerful industrial lobbies would like people to believe that we can survive while other species are quickly and quietly dying off. Irresponsible governments and businesses would have people believe that we don’t need a healthy planet to survive- even while human cancer rates are tripling every decade.
A lot of us heard about the recent extinction of the Yangtze river dolphin. It was publicized because dolphins are cute and smart, and we like dolphins. We were sort of sad that we humans were single-handedly responsible for destroying the entire millions-of-years-old species in just a few years through rampant pollution. Unfortunately the real death toll is so much higher than we hear on the news. Only a few endangered “celebrity favorites” get any notice at all.
Since animals and plants exist in symbiotic relationships to one another, extinction of one species is likely to cause ”co-extinctions”. Some species directly affect the health of hundreds of other species. There is always some kind of domino effect. This compounding process occurs with frightening speed. That makes rampant extinction similar too disease in the way that it spreads. Sooner or later- if gone unchecked- humans may catch it too.
Amphibians are a prime example at how tinkering with the environment can cause rapid animal death. For over 300 million years frogs, salamanders, newts and toads were hardy enough to precede and outlive the dinosaurs up until the present time. Now, within just two decades many amphibians are disappearing. Scientists are alarmed at how one seemingly robust species of amphibians will suddenly disappear within a few months.
The causes of biocide are a hodge-podge of human environmental “poisons” which often work synergistically, including a vast array of pollutants, pesticides, a thinning ozone layer which increases ultra-violet radiation, human induced climate change, habitat loss from agriculture and urban sprawl, invasions of exotic species introduced by humans, illegal and legal wildlife trade, light pollution, and man-made borders among other many other causes.
Is there a way out? The answer is yes and no. We’ll never regain the lost biodiversity-at least not within a fathomable time period, but there are ways to prevent a worldwide bio collapse, but they all require immediate action. Wilson, and other scientists point out that the world needs international cooperation in order to sustain ecosystems, since nature is unaware of artificially drawn borders. Humans love to fence off space they’ve claimed as their own. Sadly, a border fence often has terrible ecological consequences. One fence between India and Pakistan cuts off bears and leopards from their feeding habitats, which is causing them to starve to death. Starvation leads to attacks on villagers, and more slaughtering of the animals.
Some of the most endangered wildlife species live right in between the borderland area of the US and Mexico. These indigenous animals don’t know that they now live between two countries. They were here long before the people came and nations divided, but they will not survive if we cut them off from their habitat. The Sky Islands is one of many areas smack in the middle of this boundary where some of North America's most threatened wildlife is found. Jaguars, bison, and Wolves have to cross through international terrain in the course of their life's travels in order to survive. Unfortunately, illegal Mexican workers cross here too. People who know nothing of the wildlife’s biological needs want to create a large fence to keep out Mexicans, regardless of the fact that a fence would devastate these already fragile animal populations.
Wilson says the time has come to start calling the "environmentalist view" the "real-world view". We can’t ignore reality simply because it doesn’t conform nicely within convenient boundaries and moneymaking strategies. What good will all of our money and conveniences do for us, if we collectively destroy the necessities of life?
There is hope, but it requires radical changes. Many organizations are lobbying for that change. One group trying to salvage ecosystems is called The Wildlands Project, a conservation group spearheading the drive to reconnect the remaining wildernesses. The immediate goal is to reconnect wild North America in four broad "mega-linkages". Within each mega-linkage, mosaics of public and private lands, which would provide safe migrations for wildlife, would connect core areas. Broad, vegetated overpasses would link wilderness areas normally split by roads. They will need cooperation from local landowners and government agencies.
It is a radical vision to many people, and the Wildlands Project expects that it will take at least 100 years to complete. Even so, projects like this, on a worldwide basis, may be humanity’s best chance of saving what’s left of the planets eco-system, and the human race along with it.
Posted by Casey Kazan and Rebecca Sato.
Related Galaxy posts:
The Shiva Impact & Extinction of the Dinosaurs
Coming of Age in the Holocene
A Future K/T Impact -Would the Human Species Survive?
Past as Prelude -Asteroids & the Origins of Life
"The Great Extinction" & Rise of Modern Species
Dr Strangelove Two? -Cambridge Astrophysicist Gives Earthlings a 50/50 Chance of Making it Through the Century