A huge human effort produces a snapshot of our age

The IPCC report is a triumph of the intellect, but it will struggle to get the recognition it deserves. [1 October 2013 | Peter Boyer]

TOP IPCC chair Rajendra Pachauri and co-chair of Working Group 1, Thomas Stocker, at the presentation of the science review’s Summary for Policymakers [photo AP]. BOTTOM A graph from the report showing strong warming in each of the three decades to 2010.

The achievement of people working together can take the breath away, as in the sheer scale of China’s Great Wall or the ornate splendour of a medieval cathedral.

There’s no modern equivalent of these great public works. For all their impressive size, today’s roads, bridges and skyscrapers lack the human touch. They’re works of machinery, not man.

But handcrafted enterprises on a grand scale haven’t disappeared. They just come in different forms, like the six-yearly assessment reports of the Intergovernmental Panel on Climate Change.

The unveiling of the fifth of these began last weekend with the key report on the science behind climate change. This will be followed in six months by reports outlining climate change impacts and ways of addressing them, and by the release of the full synthesis report in October 2014.

The IPCC reports aren’t great products of political power or religion. They don’t move us in the same way as cathedrals or great walls. Some scientists say they should be replaced with smaller, more targeted reports released more often, able to draw on current science.

For instance, this latest IPCC report takes no account of current papers identifying rapid deep-ocean warming (Hobart’s Nathan Bindoff was a co-author) and estimating that burning all available fossil carbon would make Earth essentially uninhabitable by humans, by James Hansen and others.

But the whole point of the IPCC reports is that they’re big and comprehensive. In an age swamped with data and fractured by dispute, each assessment report is an anchor point, an integrated overview of our present predicament and a solid base from which to work out what we should do.

The Oxford dictionary and Wikipedia come to mind, but there’s surely little else in human history to match the ambition, scope and applied brainpower of this massive compendium of scientific information: 2000 pages and 14 chapters, 1.4 million words and 1250 figures.

The report involved over 600 contributing authors, cited over 9200 scientific publications and drew on more than two million gigabytes of numerical data. Over 1000 expert reviewers from 55 countries made 54,677 comments, each of which had to be individually addressed by author teams.

Tasmanian scientists figured prominently. As home for the Australian Antarctic Division, CSIRO Marine and Atmospheric Division, the Antarctic Climate and Ecosystems CRC and the Institute for Marine and Antarctic Studies, Hobart leads the world in IPCC lead authors per head of population.

IPCC reports are very much a public enterprise. In Stockholm last week, representatives of 110 governments, including Australia, worked through the policymakers’ summary of the science report line by painstaking line before giving it the tick of approval.

The language of the 2013 report is cautious, reflecting the innate conservatism of the IPCC and the scientific method, and the findings come as no great surprise — an indication that the report’s 2007 predecessor got it pretty well right. In light of the implications, the understatement is unnerving.

It’s over six years since the 2007 report, so our timetable now is more constricted and our need to act more urgent. Here’s what the Working Group I report has to say about the state of the planet:

• The climate system is warming strongly and continuing to do so. Over the past 30 years, surface temperatures have risen at a rate unprecedented in the instrument record. Those same 30 years have probably been the Northern Hemisphere’s warmest three decades for 1400 years.

• The largest contributor to warming is the rising level of carbon dioxide since 1750. The likelihood that humans are the dominant influence on the climate system is at least 95 per cent.

• Warming will probably exceed 1.5C by 2100 without substantial and sustained cuts in carbon emissions. If the current emissions trajectory is maintained it will probably rise above 2C.

• With ocean warming accounting for over 90 per cent of heat energy stored in Earth’s climate system, the upper ocean (down to 700 metres depth) has warmed markedly since 1970.

• The thermal expansion of the ocean, along with melting glaciers and ice sheets, has caused sea levels to rise at a greater rate over the past 150 years than at any time for 2000 years.

• If carbon emissions continue on their present track, increased melting of the big ice sheets will see sea levels rise by between half and one metre by 2100.

On critics’ claims that there’s been no warming since 1998, the IPCC points out that the first decade of this century has been easily the warmest on the instrument record, and that since 1998 heat energy has continued to accumulate at a rising rate in ocean waters.

The report also made the point that surface temperature fluctuations are built in to the climate system. Decade-long flat periods have occurred frequently during the 150-year instrument record. Ocean heat uptake and back-to-back La Nina years have contributed to a similar flattening today.

I’m not naïve enough to think for one moment that IPCC findings are the end of the matter. The authority of science has diminished from its high point a century ago, to the point where once-revered scientific knowledge now seems to have little or no influence on our behaviour.

I doubt that this scientific advice about a looming climate emergency will have much bearing on how we view the future. In the recent federal election, global climate change never got a look in. The election outcome was determined by short-term issues like refugee boat arrivals and power bills.

No matter. Evidence points to business-as-usual emissions on today’s rising trajectory delivering a dangerously unstable climate in 20 years, which would make climate change a short-term issue, up there with roads and budgets. And refugees, but this time environmental ones.

Maybe then we’ll see some action. But in 20 years our chances of success will be much lower, and the price tag much higher.

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