It is now widely accepted among scientists and environmentalists that we are now in a new geographical epoch - the Anthropocene.
The previous 10,000 to 12,000 years were the Holocene and we got a lot done in that epoch.
Photo: 123RF
We changed from hunter-gatherers to farmers, developed cities, complex civilisations and then around 200 years ago we started using fossil fuels.
Humankind's impact on the environment as a result has been huge and the term Anthropocene was coined to emphasise our central role on geology and ecology for the first time.
Professor Will Steffen is a member of the Anthropecene Working Group. He's emeritus professor of earth system science at the Australian National University and a senior fellow at the Stockholm Resilience Centre.
He told Kim Hill on Saturday Morning we might have expected the Holocene epoch to continue for thousands of years "if we hadn't interfered with it".
The earth, he says, has always swung between ice ages and warming periods, and the Holocene period should have been good for another 20,000 years or so.
"The Holocene was a sweet spot for humans, but now of course we're moving exceptionally rapidly out of that state."
As well as human activity bringing dramatic change to the geosphere (rocks, sea, ice and atmosphere), the biosphere (the living world) is also being changed beyond recognition.
"We are on the verge of the sixth great extinction; once you have that it takes evolution a long time to build diversity back up.
"Our impacts [on the biosphere] now are starting to look like an internal meteorite; very abrupt, very sharp - they're driving an accelerating extinction."
Professor Steffen says he believes there is still time to avoid the mass die-off if we act fast.
He says science is generally in agreement the Anthropocene started in the mid- 20th century, a period he says which marked the start of a "great acceleration" in consumption and emissions into the atmosphere.
Will Steffen Photo: Supplied
He says scientists were "staggered" to discover this acceleration was not related to population growth, but to consumption by the world's wealthiest countries.
"Their population had not grown very much through 1950 and beyond, but the consumption rate is staggeringly increased. We're [OECD countries] 18 percent of the world population and we consume three quarters of everything that the world produces."
Up until now consumption not population has been the problem, but that will change as countries such as China and India continue on their "development pathways".
What triggered this "great acceleration?
Steffen says three great events in the first half of the last century ushered in a new era of institutions.
"Before that, European feudal institutions … were really running the show. They were sort of holding things back.
"It took two world wars and a big depression in between to wipe the slate clean and usher in the era of institutions like Bretton Woods, the IMF, the World Bank - this greased the wheels of new technologies."
World War II also drove a huge leap in technological change and when it was over many scientists and engineers moved into the domestic economy, driving further consumption and energy use.
Professor Steffen says we still have time to turn the ship around, but only through massive societal and economic change; he does not believe adaptation, advocated by the likes of Bjorn Lomborg is the answer.
Lomborg says money is better spent on strategies to adapt rather than decarbonising the economy.
"Bjorn Lomborg vastly over estimates our ability to adapt. I've debated him in person and I don't think he understands the science of climate change very well or what the risks are all about."
He says adaption technologies such as geo engineering and carbon capture are weak strategies.
"Carbon capture is not proven and the cost is enormous. It's far, far cheaper to move to renewables and not emit the stuff in the first place."
Adaptation is only an option for wealthy countries, he says that leaves most of the world's population stranded.
"When you look at changing the temperature of the earth by 4°C that sounds like not much, but in just 100 years that's a vastly different climate system.
"Precipitation patterns change remarkably, the food bowls that we know today are disrupted at just 1°.
"A wealthy country like Australia or New Zealand may be able to adapt, but a lot of the poorer countries cannot."
We've designed an economic system, he says, that grows inequality and also "chews up the environment.
"We are the only species that destroys its own habitat."
Nevertheless Steffen is somewhat optimistic.
"I think it's a race against time, I'm seeing enough threads of changes out there. It's still possible to do it If by the end of this decade we have the resolve that we need to go in a different direction, we have a couple to decades to implement that."
