If we are spared the nuclear holocaust, then pollution and climate change would be responsible for our extinction
Since life on Earth evolved in the form of bacteria approximately 3.5 billion years ago, there had been five mass extinctions. The first one occurred 440 million years ago and the last one 65 million years ago. They had been caused by such things as climate change due to severe ice age, volcanoes, restructuring of the Earth’s crust during the formation of the super-continent Pangaea 250 million years ago, other forces of Nature and an asteroid impact.
Extinction, albeit not on a massive scale, is a natural phenomenon, a part of evolution. An examination of the evolutionary records reveals that extinction follows a pattern of species gradually becoming extinct and being replaced by newly evolved species. That’s because there is only a finite number of available niches on our planet for species to survive. Moreover, each species has a unique lifestyle not shared by any other species. As their habitat changes, their lifestyle also changes. If species cannot adapt to these changes, they become extinct. Their place is taken by species which evolves to fit the changed environment. This is known as a gradual extinction.
In the last 500 years, a short period of time on the geological scale, some 320 birds, mammals and reptiles had become extinct. The extinction of so many species over a few hundred years makes it difficult to ascribe the phenomenon to climatological, geological or astronomical events alone. It leads one to speculate that something unusual must have happened during this time frame. In particular, were these extinctions caused by humans who had and still have a greater impact on his environment? The answer is, yes.
With our entry as an ecological factor, there has been a shift from gradual extinction to abrupt, habitat-emptying extinction. We have profoundly affected the species that share the planet with us. Because of our activities, they seem to be vanishing at an unprecedanted rapid rate. This raises the question: Are we also pushing ourselves to the precipice of mass extinction?
Indeed, many scientists are predicting that we are on track for a sixth mass extinction. This time the cause won’t be global cooling or volcanic eruptions. It will be the work of a single species ‒ the Homo sapiens.
Of the many possible scenarios, nuclear conflict is the most likely one by which human civilization may become extinct in a jiffy. With the fingers of two mentally unstable men on the nuclear button, this scenario seems to be ever more likely now. After Trump’s “fire and fury” threat, the infamous Doomsday Clock was moved ahead by 30 seconds closer to midnight. The clock was created by former Manhattan Project scientists in 1947 in an effort to bring public attention to the threat of nuclear war!
If we are spared the nuclear holocaust, then pollution and climate change would be responsible for our extinction. Today, we live in a planet poisoned by toxins dumped by us. All forms of life, including human beings, are mired in a toxic swamp. The toxins are in the food we eat, the water we drink and the air we breathe. As renowned explorer and environmentalist Jacques Cousteau said: “Water and air, the two essential fluids on which all life depends, have become global garbage cans.”
We are changing the global climate by pumping about 35 billion tonnes of carbon dioxide per year into the atmosphere. According to the World Meteorological Organization, last year’s emission was 50 percent higher than the average of the past 10 years. The present concentration of carbon dioxide in the atmosphere, 403 parts per million, is the highest in recorded history.
Thus, the dangers posed by the greenhouse effect are real and scary. Global temperature is increasing, ozone layer has been depleted, hydrological cycle is being disrupted, sea levels are rising, polar ice caps are melting, tropical rainforests are disappearing, wildfires are on the rise, semiarid lands are turning to deserts and bizarre, violent weather patterns have grown in numbers in recent years. The utter devastation of Houston, many Eastern Caribbean Islands and Puerto Rico by relentless rains, punishing winds and dangerous storm surges caused by hurricanes Harvey, Irma and Maria in August and September of this year are still fresh in our memory.
What is more alarming is that if we allow our planet to become even warmer, then hundreds of millions of tonnes of frozen methane buried under the Arctic Ocean floor, often referred to as the “Arctic Time Bomb,” would be released into the atmosphere. In an article published in 2014 in the journal Science, researchers report that concentration of methane in the atmosphere has been growing rapidly since 2007. They believe that due to rising temperatures across the entire Arctic region, which are already melting the Siberian permafrost, the trapped methane is being released into the atmosphere.
In addition to methane, carbon dioxide in the rocks would be “baked out” and ocean water would evaporate into the atmosphere. Water vapor and methane are more cogent greenhouse gases than carbon dioxide. The increase of atmospheric carbon dioxide, methane and water vapor would raise the global temperature further, thereby causing more ocean evaporation, baking out of carbon dioxide and release of methane. The synergistic feedback of continued emission of these and other greenhouse gases could trigger the onset of runaway greenhouse effect which will eventually turn the Earth into an inferno with virtually no life.
Runaway greenhouse effect is not a “Chinese hoax.” Several billion years ago, Venus was cooler than what it is now and had abundance of water in oceans overlain by an oxygen-rich atmosphere. The current hellish condition on Venus where the surface temperature is a blistering 460 degrees Celsius was caused by runaway greenhouse effect.
A rapidly growing human population that more than doubled in just the last fifty years is also putting us on the throes of extinction. With a burgeoning population, food, water and a whole lot more required for sustenance of life will be in short supply. Natural resources vital to our survival are already running out faster than we can replace them with sustainable alternatives. In some cases, they have already reached their limits. Hence, it is not unlikely that once the population reaches a “critical mass,” our resources won’t be adequate enough to sustain us. As a result, starvation will bring us face-to-face with extinction, sooner rather than later.
Finally, we cannot rule out the possibility of a fast-spreading devastating disease that could wipe us out. Furthermore, with the advancement in DNA manipulation technology, it is quite likely that scientists working for the leader of a rogue nation could engineer a vicious virus or bacteria for a biological warfare and in the process obliterate our entire civilization.
For most part of the evolutionary past, we lived in a sustainable relationship with Nature, not necessarily out of choice but out of necessity. But in the past few centuries, we have gone astray. Now, we are living at odds with the natural world. We seemed to have lost touch with the magnitude of our effect on the environment. In fact, we have become a super predator pushing other species that call this planet home toward extinction.
As for ourselves, by letting population grow exponentially, burning fossil fuels unchecked, polluting the environment with toxins and facing the threat of extermination with weapons of mass destruction, we have embarked on the path to self-annihilation. Such a human race cannot survive for long unless dramatic changes are made to create a sustainable future.
Barring a nuclear armageddon, we may not witness the sixth mass extinction during our lifetime. However, one hundred years or so from now, more of human-caused stress on our planet could accelerate the occurrence of the sixth and perhaps the last mass extinction.
The writer, Quamrul Haider, is a Professor of Physics at Fordham University, New York