Human impact on Earth
July 17, 2015
There's no denying, humans have had a huge impact on planet Earth. From how we've reshaped the natural environment to climate change to biodiversity loss, our influence has been immeasurably greater than any other species. And it seems, humans are causing far more profound and fundamental changes than previously thought.
We may be pushing the earth into a "new kind of planetary state" and "in an entirely new direction with revolutionary implications for life," according to a #link:http://www2.le.ac.uk/offices/press/press-releases/2015/june/extreme-makeover-mankind2019s-unprecedented-transformation-of-earth:recent study# by researchers at the University of Leicester, published in "The Anthropocene Review." And as you can imagine - the route we're taking isn't all that good.
"The human impact is colossal," Mark Williams, a palaeontologist at the University of Leicester and lead author of the paper "The Anthropocene biosphere", told DW. "Really the bits of the biosphere that are left are embedded in human systems now. And humans are absolutely dominant."
Human-driven changes
That we are living in a new geological time period, known as the Anthropocene Epoch, isn't a brand new idea. It has gained currency in recent years with the recognition that human impact on the earth and its ecosystems could be so significant as to affect the future evolution of living species. Mass extinctions - think the dinosaurs -, global warming and fundamental planetary transformations, such as the earth's oxygenation 2.4 billion years ago, have also happened before. But Williams and his team wanted to investigate whether there was something different about this chapter in the globe's history.
They found four key changes: the unprecedented homogenization of species around the world through human-instigated species invasions; the growing interaction between the biosphere - the sum of all Earth's ecosystems - and technology; the total domination of one species on land and water; and human impact on evolution of other species.
"Humans now appropriate between 25 and 40 percent of all primary production on the planet, which is staggering for one species," says Williams. "Humans are basically influencing 75 percent of the surface of planet Earth; with just 25 percent in its natural pre-human state … Humans have effectively displaced the top predators in the ocean and terrestrial ecosystems."
According to Williams, human impact is completely unique: never before has one species in the evolution of our planet had such a profound and rapid effect on terrestrial and ocean ecosystems in that "we've completely altered them."
Humans - not mass volcanic eruptions or asteroids - may be behind a sixth mass extinction. Our activities have caused whale and fish stocks to collapse and pushed wild animals to the fringes. Land-dwelling animals like elephants, tigers and lions, now make up just 3 percent of the vertebrate biosphere.
Interplay between technology and the biosphere
Our rise to the top of the species chain didn't occur overnight. It's the conclusion of a series of events that goes as far back as humans using tools to modify their landscape. The birth of agriculture and the industrial revolution had an impact too. Then the #link:http://www.britannica.com/technology/Haber-Bosch-process:Haber-Bosch# process - devised in the first half of the 20th century - allowed mass production of nitrogen fertilizer and is widely touted as having enabled a global population explosion from 1.6 billion in 1900 to 7 billion today.
"Those are the roots of our total domination," says Williams.
As an aside, nitrate pollution from fertilizer is a major environmental problem for rivers and groundwater and poses a health risk for humans too.
But one of the biggest shifts to the earth's biosphere could come from the interdependencies between humans and technology - and the growing "interaction of the biosphere with the 'technosphere'," according to the study. The technosphere - a concept pioneered by Peter Haff of Duke University, a geologist and one of the paper's co-authors - is the "sum total of all human-made manufactured machines and objects, and the systems that control them."
"Our population of 7 billion humans can't be sustained without technology," says Williams, "but technology needs humans to sustain it. Neither can live without the other. It's a co-evolution."
Right now the technosphere is unsustainable for the biosphere. It's a parasite. If it does become sustainable, however, "this could be the biggest and most fundamental state change we've ever seen."
Alternatively, humans could go extinct or cause our own extinction in the meantime. In which case, the biosphere would recover in the short-term. Either scenario would be recognizable far into the future if another intelligent species were to look back at the geological record. The latter would be a blip, but the former "would be fundamental and self-sustaining because the process we've begun is quite irreversible," says Williams.
Still, the research team believes humans can stop the worst effects.
"Human attitudes are starting to change. We are now thinking about being stewards of nature," says Williams,"it's not the case that all is lost but that there is everything to play for."