Is human race heading towards extinction?

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

 

Noise Pollution – Plague of the Modern Society

Perennially chaotic Dhaka streets

Sound is one of many forms of expression and a very important aspect of human life. It can, however, be pleasant or unpleasant. Whether sound is as pleasant as music or as unpleasant as noise depends on its intensity, duration, rhythm and mood of the person. But when intensity goes beyond what is pleasant, it becomes a problem, and hence, a pollutant.

Noise pollution is a plague of modern society from which there is virtually no escape, no matter where we are – in our homes or gardens, on our streets, inside our cars, at theatres or concerts, social events, restaurants, parks or in other public places. Like second-hand smoke, noise has become an unwanted airborne pollutant produced by others and imposed on us without our consent, often against our will.

The unit used to gauge the loudness or sound intensity is decibel (dB). Decibel is one-tenth of a bel (B). The bel (B) measures the ratio of one intensity or power of sound to the intensity or power of the reference sound in a logarithmic scale (log to the base of 10). After that, bel is converted to dB scale by multiplying by 10. The reference level of sound intensity is 1 and hence its dB value is 0, which is taken as the threshold of hearing. A sound 10 times as loud as the reference level has a dB value of 10. A 20 dB is 100 times as loud as the threshold of hearing, 30 dB is 1000 times, and so on. The maximum loudness humans can be subjected to, after which sound can be felt rather than heard, is approximately 120 dB. This is known as the threshold of pain.

Among the many sources of outdoor noise pollution, automobiles are the worst offenders in the western world, followed closely by trucks, buses, motorcycles and low-flying airplanes. Construction equipment, such as jackhammers, compressors and bulldozers, also contribute substantially to noise pollution. Noise levels of these sources range from 50 dB to 120 dB. But in Bangladesh, high dB speakers at the top of mosques are the worst offenders. In some residential places close to the mosques, noise levels exceed 120 dB or 130 dB quite regularly.

Those living within 600 metres of an airport are exposed to 100-120 dB of noise from jet planes taking off. At 1,500 metres away, the level drops to 80 dB. A car cruising at 100 kmph, 80 metres from the pavement’s edge would produce 75 dB. Because of the logarithmic nature of decibel, adding sound intensity from two cars would increase the level by 3 dB; three cars would augment the level by 4.8, and so on.

Some household appliances, such as dishwasher, food blender, air conditioner and vacuum cleaner, are annoyingly loud – 70 to 100 dB. Depending on the distance from the source, sound from living room audio and video systems could be near 80 dB.

In Dhaka, irrespective of where you live, the noise intensity level is very close to the threshold of pain. Most of it is due to the religious cacophony and noise produced by the horns of vehicles plying on the roads, highways, byways and lanes of the city. Although noise is a controllable pollution, government of Bangladesh has done very little to alleviate the suffering of its citizens from this pestilence.

Hearing damage from loud noise depends on the decibel level, length of exposure and distance from the source. According to the US Occupational Safety and Health Administration, if you are exposed to 95 dB and above for four hours a day over a long period, you will slowly start to lose your hearing ability. As the damage from noise exposure is usually gradual, you might not notice hearing loss until it becomes acute.

Damage from loud noise can be temporary or permanent, depending on whether the organs of Corti, the receptor organs in the inner ear, are impaired or destroyed. In the extreme case, exposure to 150 dB would rupture the eardrum. Less intense, but severe noise can interfere with cellular processes in the organs that cause their eventual breakdown. Unfortunately, the cells of these organs do not regenerate.

Generally, younger persons are more tolerant of loud noise than older persons because their protective mechanisms are more effective. This tolerance does not necessarily make them immune to adverse effects from loud noise. For example, blood tests done on children living near airports in Munich, Germany reveal significantly higher levels of adrenaline and cortisol – the body’s stress hormones, than children living in quieter neighbourhoods. The increase in cortisol adds to the risk of having a heart attack or stroke later in life. Similar impacts have been documented among adults near Amsterdam’s Schiphol and Stockholm’s Arlanda airports, where chronic noise as low as 55 dB correlated with more doctor visits, high blood pressure and treatments for heart troubles.

And what about the sound of music? The line that separates music and noise is thin and subjective. While to some people noise may not be an issue, others consider contemporary music and music from other cultures to be noise pollution. Take heavy-metal and rap, for example. They are considered to be music by many people, though most of the songs cannot be transcribed into notes and some of them don’t even have melody.

Is hearing permanently impaired when attending concerts that feature very loud music? Yes, they are because typical sound intensity level of a loud rock concert is near the threshold of pain. Of course, the extent of impairment will depend on how long you are exposed to the noise and how often you attend such concerts. That’s why many musicians and DJs wear earmuffs to protect their hearing organ from the harmful effects of noise. A drop of 30 dB corresponds to a decrease in intensity (not intensity level) by a factor of 1000.

A growing body of evidence confirms that noise pollution is taking a toll on our health and happiness, too. Studies have linked excessive noise levels to the occurrence of aggressive behaviour, constant stress, fatigue and hypertension. These in turn can cause more severe and chronic health issues later in life. Repeated exposure to noise also reduces sleeping hours, thereby, decreasing the productivity of a person.

According to a World Health Organisation (WHO) report to the UN Conference on Environment, “Of all environmental problems, noise is the easiest to control.” However, the question of control will arise only after we become aware of the seriousness of the problem, and the government finds some solution for it.

The writer is a Professor of Physics at Fordham University, New York.