Here are some shocking facts about the human impact on Earth. We have produced enough concrete to build a 2mm thick Earth replica. We’ve produced enough plastic for Earth to be wrapped in clingfilm. We are creating ” technofossils,” which is a term for congealed materials made by humans – concretes and plastics – which will last for millions of years.
The most alarming aspect of human impact on Earth’s ecosystem is its scale.
In 2000, Paul Crutzen, a Nobel laureate, and Eugene Stoermer argued that the human impact on Earth’s atmosphere, oceans, land, and ice sheet had reached a level that had propelled Earth into a brand new epoch. The Anthropocene was the name they gave it, and they argued that the current Holocene period had ended.
The Holocene began 11700 years ago when we emerged from an ice age. The Holocene is characterized by a stable earth system over the last 10,000 years. This stability allowed us to develop agricultural systems and, eventually, villages and towns – the human civilisation.
We use some pretty strong rhetoric to describe the Anthropocene and its current human impact. The Economist said in 2011 that humanity had “become an incredibly powerful force of nature, reshaping our planet on a geological level.” Like an asteroid, we are a force of nature. We are like an ice age.
What does it really mean? What does this mean? Does it mean that, for instance, we have as much impact as the natural forces right now, or is it somehow more profound than these natural forces?
Humans: The new asteroids. Steve Jurvetson CC By
Maths and the Anthropocene
In our study we sought to find the easiest way to describe the Anthropocene mathematically and to articulate the differences between the former and current functioning of the planet.
The size and chemical composition of Earth’s atmosphere, oceans, and ice sheets have changed over the years due to changes in the Sun’s energy output, or by major asteroid impact like that which killed the dinosaurs.
Now it’s your turn. Matthew J Parker, CC BY-SA
Geophysical forces can also cause changes: continents crash and cut off ocean currents, causing heat to be distributed in a different way. This disrupts climate, as well as biodiversity.
The system itself can also cause a shift. New life, for example, is responsible for great changes in the planet’s orbit. Energy is needed to adapt to oxygen.
We can start with an article from 1999 by Earth System Scientist Hans Joachim Schellnhuber. From this, we can conclude that the rate of Earth system change (E) is driven by three factors: astronomical forces such as those of the Sun and asteroids, geophysical forces such as changing currents, and internal dynamics such as the evolution of cyanobacteria. Let’s call these A, G, and I.
We can express it mathematically as follows:
The statement reads as follows: the rate at which the Earth system changes (dE/dt) is determined by astronomical, geophysical, and internal dynamics. This is a simple statement that explains the main drivers in the system.
Since the first living organisms evolved, this equation has held for 4 billion years. Schellnhuber claimed in his article that humans must be included in this equation, but he made his argument before the full impact on humanity was assessed. This equation has changed dramatically in the last few decades.
We are losing biodiversity tens or hundreds of times faster than natural rates. In fact, we’re approaching mass extinction rates. Five mass extinctions have occurred in the history of Earth. Humans are the cause of the sixth.
The rate at which we emit carbon dioxide may be at an all-time high. The global temperature is rising 170 times faster than the Holocene baseline. The global nitrogen cycle has undergone its most rapid and largest change in 2.5 billion years.
The rate of change in the Earth system caused by human activity over the last four decades has been so rapid that we can now demonstrate the equation as: