Loss of old certainties hobbles IPCC


I’ve just blown a large quantity of dust from my copy of the very first Assessment Report published by the Intergovernmental Panel on Climate Change in 1990. I see that it cost me £19.95, yet I’m not aggrieved to observe signs that 336 of the 337 pages of scientific prognosis have never seen the light of day.

Sir John Houghton ©C3W

Sir John Houghton ©C3W

That single page Executive Summary played a small part in settling the compass of my life, which at the time was in search of direction. Presumably written by the redoubtable Working Group chair, Dr John Houghton, the Summary’s opening words – “We are certain” – conveyed what I expected from a report endorsed by “most of the active scientists working in the field.”

Two more confident sub-headings frame the Summary: “We calculate with confidence” and: “Based on current model results, we predict”

In just 300 words, policymakers preparing for the 1992 Earth Summit could appraise the causes of climate change, the projected rise in temperature and sea level, and the range of uncertainty. The frightening speed of what was happening in relation to natural planetary cycles was enough for me, then as now, to conclude that we have an existential problem on our hands.

Scientists working in 2013 on the IPCC Fifth Assessment Report must look at Houghton’s text rather as the safety design team at Jaguar Land Rover might view the E-Type. The Physical Science Basis Summary published for policymakers last Friday contains no such helpful phrases: “we are certain” or “we predict”. Instead, the opening page introduces the topic of “probabilistic estimates of quantified measures of uncertainty.”

The text is weighed down with introspective statements validating the core concept of anthropogenic global warming by reference to observed change. Whereas the First Assessment Report allocated just one of its eleven sections to the question: “Has man already begun to change the global climate”, its successor devotes the first 11 of 19 headline messages to self-justifying evidence that the climate system is already behaving unnaturally.

I’m not sure that my 1990s self would have made it as far as page 14 where the section on Future Climate Change finally begins. Its opening headline offers the underwhelming news that “continued emissions of greenhouse gases will cause further warming.”

I’ve no doubt that the structured communication of uncertainty developed by the IPCC since 1990 represents an improvement in the scientific method. But the imposition of formulaic degrees of confidence in findings and likelihood of projections has been disproportionate to the overwhelming scale of the problem.

It’s one of the great paradoxes of our time that the precautionary principle in ecosystem management has been imposed so rigorously on the scientific method and so negligently on the unfortunate planet, for whose benefit it was adopted by politicians in the Rio Declaration of 1992.

The irony is that the sloppy science and clunky computers of the First Assessment Report produced results which have stood the test of time. Each of the confident predictions for 2100 in that 1990 Executive Summary would not look out of place in the Fifth Assessment projections; the temperatures are a little high and the sea level rise a little low. There’s even a prescient aside in the text warning that “the rise (in temperature) will not be steady because of the influence of other factors.”

The science of climate change is therefore marking time, in contrast to its cause. We all know what’s gone wrong – the failure of the political process in the so-called great democracy of the United States to counter the power of fossil fuel interests.

The IPCC agenda is now driven, not by contemporary anxiety about a sustainable planet, but by media campaigns of dubious partiality. Friday’s publication even analyses periods beginning with the infamous hot year of 1998, reducing the IPCC to the level of its critics. Many of the projections are suspiciously tepid, like a tray of hot canapés that has been hawked around a large room.

We can’t go on like this. The IPCC scientists have done a heroic job in standing their ground against the attack dogs, proving that their work and their methods are sound. But it’s time for the UN to take a careful look at the role of the IPCC, in the context of broader global environmental change – and of its milestone decision last week to pull together disparate programmes into a set of Sustainable Development Goals to take effect from 2015.

Summary for Policymakers from Fifth Assessment Report

Summary for Policymakers from First Assessment Report

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