As the Australian public baulks at even a modest carbon price, climate change activists have set their sights on what is pragmatic and convenient, not what is truly necessary, writes Greg Foyster.

On June 18, the Australian Senate launched an inquiry into "The Abbott Government's attacks on Australia's environment, and their effects on our natural heritage and future prosperity".

Initiated by the Greens, the inquiry lists a litany of grievances: abolishing the Climate Commission and the Biodiversity Fund, attempting to scrap the Clean Energy Finance Corporation and carbon price, cutting funding to Environmental Defenders Offices, and attempting to de-list a swathe of forest from the Tasmanian Wilderness World Heritage Areas.

It was an obvious political ploy, and the message was clear: the Coalition is tearing through Australia's environmental programs like a Hummer bush-bashing in the Daintree.

Green groups are in emergency mode, launching reactionary campaigns - Protect our solar industry! Save the Reef! Show you care about Tassie's forests! - to salvage what they can. Meanwhile, a much bigger emergency rumbles in the distance, one that's not getting the airplay it should. I'm talking about the possibility that the 'official' solution to climate change - negotiated at global level - may not be enough to avert catastrophic warming.

The United Nations climate negotiation aims to stabilise greenhouse gas concentrations "at a level that would prevent dangerous anthropogenic (human induced) interference with the climate system". For the past two decades, the danger threshold has generally been interpreted as two degrees Celsius above pre-industrial levels, a target reaffirmed in Copenhagen in 2009.

But is two degrees too high? Some leading climate scientists seem to think so.

In 2011, Professor Kevin Anderson, then director of the UK's Tyndall Centre, co-authored a paper arguing that two degrees represented a threshold not between dangerous and safe, but between dangerous and "extremely dangerous". NASA's James Hansen has described the two-degree target as "a prescription for long-term disaster".

And yet lower targets are mostly off the table. The IPCC's latest report says only a limited number of studies have explored scenarios to keep the temperature rise under 1.5 degrees by 2100. It's easy to understand why: this lower target requires an immediate plunge in emissions and energy demand. It's considered politically unfeasible. And so we set our sights on what is pragmatic and convenient, not what is truly necessary.

Writing in Nature in 2012, Professor Kevin Anderson and Dr Alice Bows argued "catastrophic and ongoing failure of market economics and the laissez-faire rhetoric accompanying it (unfettered choice, deregulation and so on) could provide an opportunity to think differently about climate change".

But where is the discussion about the unorthodox, radical solutions that may be required?

On June 21 and 22, about 300 environmentalists and academics attended the Breakthrough National Climate Restoration Forum in Melbourne to address these very questions and take a sobering look at what mitigating catastrophic warming really entails.

The first session laid out the global emergency we face. Danny Harvey, a geography professor at the University of Toronto, described how two degrees of warming risked 10 to 30 metres of eventual sea level rise, significant dieback of the Amazon, and a near total loss of coral reefs.

Climate analyst David Spratt argued that even the IPCC's most ambitious carbon budget to stay below the two-degree target has a one-in-three chance of failure. If humanity wants a less than 10 per cent probability of exceeding the two-degree target, he said, then "there is no carbon budget left".

Understanding risk is essential because the globe doesn't warm in a steady, linear fashion. Brett Parris from Monash University argued the climate record shows a sudden shift between equilibriums. But economists and policy makers are hoping they can manipulate the climate to a point that suits them - two degrees, or even three or four degrees - without knowing where the real threshold lies. "What if there's no equilibrium between one degree and six degrees of warming?" asked Parris.

A second question hovers over how to achieve the two-degree target. Unless emissions peak before 2020, we're looking at emissions reductions rates of up to 9 per cent per year, which has historically been associated only with severe recession. Several forum speakers argued this calls for economic restructuring on the scale and speed of mobilisation for WWII. This would involve market interference, a more central "command and control" style of government, and possibly electricity rationing.

That brings us the most radical proposal of all. David Keith, a professor of public policy and applied physics at Harvard, presented a case for climate engineering, a hubristic scheme to cool the planet by spraying sunlight-reflecting sulphur particles into the upper atmosphere. The technology would be used to slow the rate of change, not mask the effect of all emissions, but it still carries big risks. It's an indication of the seriousness of climate change that the environmentalists in the audience didn't openly revolt at the suggestion of directly interfering with the planetary thermostat.

As the Abbott Government continues attacking environmental programs and the Australian public baulks at even a modest carbon price, green groups might be reluctant to broach more radical solutions. But if they don't agitate for what's truly necessary, as opposed to what's politically convenient, then who will?

It's time we had a frank - and frightening - discussion about the catastrophe we're heading for and the full suite of options available to turn the situation around. Is two degrees too high? Do we need to restructure the economy? Is climate engineering inevitable? These are the climate debates we have to have, and soon.

This article was first published on the ABC's Environment portal. See the original here.

Greg Foyster is a Melbourne journalist and the author of Changing Gears: A Pedal-Powered Detour from the Rat Race. View his full profile here.