The "H" Represents Us

For the first four billion years since the beginning of life on Earth, "the rate of change of the Earth system (E) has been driven by three things: astronomical forcings such as those from the sun or asteroids; geophysical forcing, for example changing currents; and internal dynamics, such as the evolution of cyanobacteria. Let’s call them A, G and I."

This is the algebraic formula proposed by Hans Joachim Schellnhuber way back in 1999.

Unfortunately Schellnhuber wasn't able to factor in humankind's contribution at that time. Now we can. Change over the past four decades has been both rapid and abrupt, utterly eclipsing change from the natural influences of the first four billion years. A, G, and I are now effectively negligible.

A, G and I are now approaching zero relative to the other big force – us – they have become essentially negligible. We are now the dominant influence on the stability and resilience of the planet we call home.

This is worth a little reflection. For four billion years, the Earth system changed under the influence of tremendous solar-system wide forces of nature. Now this no longer holds.

Heavenly bodies of course still exert some force; so does the ground beneath our feet. But the rates at which these forces operate are now negligible compared with the rate at which we are changing the Earth system. In the 1950s or 1960s, our own impact rivalled the great forces of nature. Now it usurps them entirely.

This should come as a shock not only to environmentalists but to everyone on Earth. But our conclusion is arguably a modest addition to the canon of academic literature. The scale and rate of change has already been well established by Earth system scientists over the past two decades.

The new math, shown below, introduces the H factor, humankind, displacing A, G, and I.

The message in all this?


Scientific and technological innovations and economic policies promoting growth at all costs have created a consumption and production vortex on a collision course with the Earth system.

 Now, only a truly catastrophic volcanic eruption or direct asteroid hit could match us for impact.

So, can the Anthropocene equation be solved? The current rate of change must return to around zero as soon as possible. It cannot continue indefinitely. Either humanity puts on the brakes or it would seem unlikely a global civilisation will continue to function on a destabilised planet. The choice is ours.

To sum it up, humans today are causing climate change to accelerate at a rate 170 times faster than natural forces.  Most of this man-made acceleration has occurred over the past half century.