A geological litmus test
The geochemical fingerprints of human activity are everywhere.

Since the industrial revolution the added CO₂ now dissolved in the oceans has increased acidity by 25%. And it is changing the geological processes operating at the sea floor.

We can see traces of the lead we have mined from Broken Hill in modern sediments all around the globe – a geochemical fingerprint of Homo sapiens to be preserved for time immemorial, like the iridium anomaly that marked the end of the dinosaurs 65 million years ago.

We even make earthquakes.

The largest earthquake in Victoria in the last 30 years was the magnitude five Thomson Dam quake, induced as a direct consequence of the filling of the Thomson dam.

Induced quakes are a common occurrence when we first fill large dams, with the largest record being a magnitude six quake in India.

Anyone who has seen film of a volcano erupt or those horrific scenes of devastation from the recent Japanese earthquake and tsunami can intuitively appreciate the immense energy involved in the natural processes that shape our planet as it vents heat stored deep within its interior.

The rate heat is released from the earth – a measure of its natural “metabolic rate” – is well understood. It’s about 44 trillion watts, and reflects the average rate of energy transferred in moving all the continents, making all the mountains, the earthquakes and the volcanoes on our planet in a process we call plate tectonics.

By way of contrast, the International Energy Agency estimates our human “energy system” operates at a rate of some 16 trillion watts.

So we are already operating at one-third the rate of plate tectonics, and with our energy use doubling every 34 years we are on course to surpass plate tectonics by about 2060.

Climate scientists talk about the climate sensitivity in terms of a “radiative forcing” – an obscure term that accounts for the rate of heat energy gain or loss due to a change in a climate parameter.

The radiative forcing of a doubling of CO₂ is about 1300 trillion watts – or 28 times the energy released by plate tectonics.

And we are well on the way to doubling CO₂. In the past hundred years we have added almost 40%, and warming that can only plausibly be attributed to a greenhouse effect is not only heating the atmosphere, but is also pumping heat into the oceans and the crust at a phenomenal rate.

When my students measure the temperature in boreholes across Australia they invariably see that almost as much heat is now going into the upper 30-50 metres of the Earth’s crust as is trying to get out – a result entirely consistent with the surface temperature rises measured by climate scientists.

Recent measurements suggest the oceans have been heating at 300 trillion watts over the last few decades.

The scale of our energy use is truly mind-boggling. In fact, the sheer size of these numbers makes it difficult for most people to grasp and comprehend their significance; few of us have any useful reference frame for comparison.

An old story retold
Why was a really famous geologist writing this when human population was just one third, and CO₂ emissions from burning fossil fuel just 10%, of today’s rates?

For one thing Woodward was aware of the work of another giant of science – the Swedish chemist and Nobel Laureate Svante Arrhenius whose name is still part of the everyday chemistry vernacular.

Arrhenius demonstrated the greenhouse effect of CO₂ in 1896 estimating that a doubling of atmospheric CO₂ would lead to a temperature rise of 5-6°C. A few years later he settled on a 1.6°C warming, not far off the current consensus of 2-4.5°C.

The scientific basis for the CO₂ greenhouse effect was established over 100 years ago, before Einstein and relativity, before the Curies and radioactivity, and before Fleming and antibiotics, not to mention DNA, quantum mechanics and plate tectonics.

In fact it precedes just about everything we think of as modern science, not to mention Leninism.

In his 1923 book, Sherlock commented “Man’s work is … as worthy of a place in geological text-books as are the actions of the sea or the rivers".

The dawning of a new geological era
It would be no surprise to Sherlock or Woodward that the international geological community is now considering inaugurating a new geological epoch – named the Anthropocene – in recognition of the geological impact of our own species.

While climate sceptics are surely not alone in having a sense of disbelief in the immense scale of human activity, these figures speak for themselves.

We are indeed a geological agent of unprecedented power.

Faced with that stark reality now, it would be folly at best to maintain the fiction that we are too puny to impact the planet – at worst, it is just plain reckless.

Whether we like it or not, for better or for worse, we are already engineering our planet.

This is the fourth part of our series Clearing up the Climate Debate. To read the other instalments, follow the links below:

Part One: Climate change is real: an open letter from the scientific community.

Part Two: The greenhouse effect is real: here’s why.

Part Three: Speaking science to climate policy.

Well, that IS the entire basis of Abbott's Direct Action policy. But Labor and the Greens and anyone else with two brain cells to rub together understands that using the market to put a price on emissions is by far the cheapest mechanism for reducing emissions.

low carbon economy that CAN "have an effect" on climate change

Quote:



ISNT THE TAX SUPPOSED TO BE ONE OF THE FACTORS TO REVERSING CLIMATE CHANGE ???

SO HOW DO WE MEASURE IF A LOW CARBON ECONOMY IF WE BECOME IS REVERSING THE UNDERSIRED CLIMATE CHANGE,