It's business as usual and we are finding it hard to change our ways to avoid serious climate change, ANU academic Tony McMichael writes.
It's a pity that no cosmic authority was able able to impose a pre-commitment limit on our global emission of greenhouse gases - particularly since we have not yet fully understood the stakes we are playing for. In reality we are all big-time gamblers now, gambling with the planet's future.
The early players, the industrialised Western countries, have much more than doubled their money. Newer members of the coal-burning league club are now keen to double theirs. It looks easy: you just feed in units of fossil fuel, press a few buttons and out comes a pile of new money. Well, actually, out comes a bit more than money, and into the atmosphere it goes.
This is no frivolous analogy. We mostly live for the present. We judge success on wealth generated. We are, say the evolutionary neuroscientists, hardwired for optimism. We prefer not to consider future penalties, and we are good at discounting the future. (As Groucho Marx asked: ''What did the future ever do for me?'')
As we become more deeply enmeshed in this global gamble, we seek reassurance by rationalising our position. That's what gamblers do.
Indeed, reassurance is sometimes taken from the realms of irrationality. Several US Republican senators are on record as arguing that the Good Lord made a covenant with Noah that, after rinsing away the grubby sins of the world, He would not need to disrupt the world again. Ipso facto, climate change is permanently off the divine agenda.
Meanwhile, others who think a little more rationally seek reassurance from the fact that at least emissions targets are being set for 2050 (though stringent between-times targets are not). Or perhaps we can muddle through with adaptive responses as conditions deteriorate. Or maybe radical technological solutions, even global-scale geo-engineering, are just around the corner. (Hmmm ... like nuclear fusion, a malaria vaccine, gene therapy to avert obesity, and other breakthroughs that have been just a few decades away for several decades.)
For some, though, reassurance is more elusive. A growing number of expert scientists worry that, on current trajectories of population growth, resource depletion and environmental disruption, we could lose our shirt. And more.
Here the analogy with poker machines falters. Sitting at a pokie, we have a pretty good idea of the range of possible outcomes - and which of them is most likely. However, there is much that remains unknowable about the Great Gamble we are taking with the ''Earth system'' as our disruptive environmental impact grows. We are entering unfamiliar and high-risk territory.
Fortunately, the main physical indicators and early-stage risk markers for climate change are becoming fairly well understood. In contrast, the consequences of acidifying the world's oceans, doubling the amount of biologically active nitrogen compounds in the biosphere, eliminating species faster than ever before (since the emergence of vertebrate animal life), depleting most of the world's great aquifers, and mobilising infectious agents at an accelerating rate are all much less easy to anticipate. Yet these unprecedented human-caused changes to Earth's environmental and ecological systems are probably now closing off options for future generations. We are, say some scientists, moving into ''an unsafe operating space'' as increasingly we transgress safe environmental limits.
For climate change we know the pre-commitment that should be guiding us - the upper limit of cumulative carbon emissions if we are to avert ''dangerous'' climate change (estimated to be a rise of above 2 degrees Celsius). Guidance is laid out in the recent report by the Centre for Australian Weather and Climate Research on this allowable cumulative ''global carbon budget''. To have a 50:50 chance of limiting the global temperature rise to 2 degrees Celsius, total future carbon emissions must not exceed 450 billion tonnes.
Currently, our global carbon emissions are approximately 9 billion tonnes per year, and rising. If, via extraordinary international effort, we halted this uptrend by later this decade, we would then need to reduce global carbon emissions by about 7 per cent each year through to 2050 - and then beyond, until emissions become zero. To raise our chance above 50:50 of avoiding over 2 degrees warming, the recurrent annual emissions cuts must be even steeper.
Meanwhile, the emissions reduction pre-commitment becomes increasingly formidable as each year passes - and as we defer actions to slow global population growth and to accelerate the development of energy-saving technologies and renewable energy sources in base-load-compatible configurations.
We argue about spending a few hundred million dollars on upgrading and fitting out the nation's poker machines to achieve a socially desirable pre-commitment policy. Meanwhile as planetary gamblers, baulking at an urgently-needed commitment, we may face much bigger losses in future.
Tony McMichael, Professor of Population Health, heads the ANU's research program on climate change and human health.