Human Overpopulation: Have We Become An Invasive Species?

Reno Berkeley

Have human beings become an invasive species? With a sixth mass extinction underway, the planet's future hangs in a precarious balance that may already be tipped irreparably.

Since our reliance on fossil fuels began, the human population has accelerated. Because of this, and because of the severe environmental changes occurring at rapid speed, it has become clear that human overpopulation is putting an enormous burden on Earth's ecosystem.

Forests, which absorb carbon dioxide and give us life-sustaining oxygen, are being cut down at an alarming rate for lumber and farmland. Ecosystems that have developed over thousands of years are being scraped away for real estate development and agribusiness interests.

During man's time on this planet, our species has been responsible for much of the environmental catastrophes that have occurred.

The Rise And Fall of Easter Island

Take Easter Island, for example. Before 2000 BC, the small, 63-square-mile island had no human inhabitants. According to Easter Island Travel, Southeast Asians began expanding into the Pacific Ocean, finally reaching Easter Island by 1000 AD. Later, another migration occurred, this time from South America. Historians and anthropologists believe this second wave of pre-Incan settlers brought with them sweet potatoes, one of the later staples of the Easter Islanders' diets.

Easter Islanders enjoyed a rich and diverse diet of native plants and animals, and a complex society that expanded to about 9,000 by 1550. However, because of overpopulation and stress on the island's natural environment, the number of inhabitants had dwindled to fewer than 3,000 by the time the first known Europeans made contact in 1722.

Within 700 years, the lush, green island had become barren, stripped of trees, either by slash-and-burn farming or by Polynesian rats, which feasted upon tree roots and seeds. More than 16 million trees were decimated (in part for transporting the colossal stone carvings) native bird species no longer called the island home, and according to a report by the PBS program Nova, the inhabitants had even resorted to cannibalism to survive.

The island experienced a profound and devastating ecological collapse due to human intervention and uncontrolled population growth. In other words, human beings became an invasive species.

Can We Survive Mass Extinctions?

A June 2015 National Geographic interview with environmental journalist Elizabeth Kolbert discusses the elevated levels of extinctions, and how human beings are a direct cause.

There are very few, if any, extinctions that we know about in the last 100 years that would have taken place without human activity.

If you give vertebrate species (and we are another vertebrate species) an average lifetime of a million years, and you say humans are 200,000 years into their million years, and you precipitate a mass extinction—even laying aside the question of whether humans will be the victim of their own mass extinction—you can't expect that same species to be around by the time the planet has recovered.

It seems, then, that the idea of human beings as an invasive species makes sense. Wherever we go, human beings bring death, disease, and destruction, all in the name of progress.

In Kenya, the Northern White Rhino is as good as extinct, with only three remaining animals left alive in the world. Of those, just one is a male, and experts believe he may never mate. In-vitro fertilization has never worked on rhino species, so saving these animals from human-perpetuated extinction is a near impossibility.

In North Dakota, members of tribal nations from around the country have gathered to oppose a fossil fuel pipeline proposed to run beneath the Missouri River, according to Los Angeles Times. It may seem far-fetched that this is a case of the human-as-invasive-species, but considering the environmental ramifications of an oil pipeline running beneath a vital river near the Standing Rock Sioux reservation, it is hard to see it as otherwise. On the contrary, it is a perfect example of human beings acting in an aggressive, invasive manner against a group of people to the detriment of the environment and its inhabitants.

One of those resources is water. In many places, aquifers are being pumped out faster than they can be replenished due to factory farming. Large scale mono-agriculture would not be possible without fossil fuels for tractors, trucks, electricity for water pumps and fertilizers. Sustainable energy is beginning to ramp up, but so far, is not enough to keep up with existing demand for energy.

With the cheap access to factory-farmed produce and over-processed foods, families left their farms and relocated to cities, where each generation has lost the knowledge of sustainable farming. But with convenience, comes a great cost. Clean water is becoming a precious commodity, with communities around the nation (not the mention the world) falling victim to poisoned water pipes, dried up wells, and shrinking lakes and rivers.

Historically High CO2 Levels

Compounded on all of this, the most convincing argument for the humans-as-invasive-species argument is the fact that current carbon dioxide levels are higher than they have ever been in recorded history. According to NASA, most of the Earth's previous climate changes "are attributed to very small variations in Earth's orbit" that affected the amount of solar energy that hit the globe.

However, in the last 1,300 years, the amount of carbon dioxide in the atmosphere has increased, with the most dramatic rise occurring in the 20th century. This corresponds directly to the boom in human population growth. Today, the atmosphere currently has 400 parts per million (PPM) of carbon dioxide, an amount that has never been experienced in 400,000 years.

NASA reports that the acidification of the oceans has increased by 30 percent since the Industrial Revolution, a direct result of human beings pumping more carbon dioxide into the atmosphere. Coral reefs are collapsing, fish are dying off in record numbers, and other aquatic sea life is under stress due to the snowballing of human overpopulation.

Animal species naturally go extinct after thousands of years, but human intervention has caused a dramatic acceleration of mass extinctions. In a 2014 article, National Geographic gives a rate of extinction of up to 1,000 times faster due to human activity.

The two polar ice caps are melting at alarming rates, along with the Himalayan glacier. World Economic Forum reports that the Himalayan "ice cap" is the third largest in the world, and scientists have noted that since 2005, its melt rate has almost doubled.

Dust and pollution from car exhausts and coal burners is settling on the ice, causing it to absorb the rays of the sun, rather than reflect them away.

[Photo by Ted S. Warren/AP Images]