From The Guardian (Melissa Davey):
For the first time, researchers have developed a mathematical equation to describe the impact of human activity on the earth, finding people are causing the climate to change 170 times faster than natural forces.
The equation was developed in conjunction with Professor Will Steffen, a climate change expert and researcher at the Australian National University, and was published in the journal The Anthropocene Review.
The authors of the paper wrote that for the past 4.5bn years astronomical and geophysical factors have been the dominating influences on the Earth system. The Earth system is defined by the researchers as the biosphere, including interactions and feedbacks with the atmosphere, hydrosphere, cryosphere and upper lithosphere.
But over the past six decades human forces “have driven exceptionally rapid rates of change in the Earth system,” the authors wrote, giving rise to a period known as the Anthropocene.
Steffen and his co-researcher, Owen Gaffney, from the Stockholm Resilience Centre, came up with an “Anthropocene Equation” to determine the impact of this period of intense human activity on the earth.
Explaining the equation in New Scientist, Gaffney said they developed it “by homing in on the rate of change of Earth’s life support system: the atmosphere, oceans, forests and wetlands, waterways and ice sheets and fabulous diversity of life”.
“For four billion years the rate of change of the Earth system has been a complex function of astronomical and geophysical forces plus internal dynamics: Earth’s orbit around the sun, gravitational interactions with other planets, the sun’s heat output, colliding continents, volcanoes and evolution, among others,” he wrote.
“In the equation, astronomical and geophysical forces tend to zero because of their slow nature or rarity, as do internal dynamics, for now. All these forces still exert pressure, but currently on orders of magnitude less than human impact.”