Persistent climate deniers reject the idea that the climate is changing. When they see an increase in extreme weather events, however, they move to the next level down in denial.
“OK, the climate is changing but humans are not to blame. It’s the sun, volcanoes and other natural forces changing the climate,” they say.
Now Canberra-based (when not in Sweden) Prof Will Steffen and his colleague from the Swedish Resilience Center, Owen Gattney, have come up with an equation that shows human influence on climate is far, far greater than natural forces. For the past 7000 years, these natural forces were leading to a decline in temperature of 0.01°C per century.
Climate changing thanks to human activities 170 times faster than natural tempo
For the past 45 years, however, temperatures have increased, not decreased, at a rate of 1.7°C per century. This dramatic turnaround can only be explained by human activity. It is causing the climate to change 170 times faster than natural forces.
After publication of this ‘Anthropocene Equation’, the Bulletin met up with Will Steffen over coffee. He said it was Earth system scientist John Schellnhuber, who in 1999 came up with an equation to measure rate of changes in the Earth system (E).
Schnellnhuber had said this rate of change was driven by astronomical forcings (A) such as those from the sun or asteroids; geophysical forcing (G), for example, changing currents; and internal dynamics (I), or biological forces, such as the new presence of cyanobacteria billions of years ago which emitted oxygen, once a toxic element, but which gave rise to oxygen-tolerant life on Earth.
That equation read:
dE = f(A,G,I)
Steffen explained that human activities (H), largely in industrial societies, were dwarfing A, G and I that were now almost insignificant against H. In fact, A, G and I were trending towards zero. The new equation thus reads:
dE = f(H)
dt A,G,I → 0
In other words, humanity not only rivals the great forces of nature, it is now the prime driver of change in the Earth system.
If, however, humanity is to survive, the current rate of change must also trend towards zero as soon as possible. Global civilisation cannot survive on a destabilised planet.
What then constitutes human activities, or H? Steffen said H was a function of the three factors (P,A,T) in the original Ehrlich/Holdren equation of I=PAT, where impact on the environment was a function of population (P), affluence (A) and technology (T).
In past 7000 years, natural forces led to decline in temperature of 0.01°C per century. Past 45 years, temperatures have increased at rate of 1.7°C per century.
When in Australia, Steffen is a leading spokesman for the now crowd-funded Climate Council, which emerged after then Prime Minister Abbott axed the Climate Commission. He is gloomy about progress in Australia in dealing with climate change, particularly at the federal level where Cabinet members are actively spruiking the benefits of so-called ‘clean’ coal.
“We have to get the power to organise energy policy back to the states,” he says. “South Australia has moved significantly towards renewables. Premier Jay Weatherill has been a real leader.
“And in Victoria, the Labor Government is planning to build Australia’s first grid scale battery storage facility.”
Considering the greenhouse emissions of natural gas
Steffen warns against using gas as a transition fuel between fossil fuels and renewables.
“There is very little difference in emission terms between coal and gas if you consider the whole life cycle. When fugitive emissions from coal seam gas are taken into account, gas is no better.”
Steffen concedes there is some use for gas to provide ‘peaking power’ at times of high demand, as in heat waves. He says we have to get past the concept of ‘base-load power’ which is often used to justify the continued use of coal into the future.