Climate change debate in decline

Scientist-activist James Hansen joins a protest to highlight the dangers of climate change in Coventry, England. (AFP)

Scientist-activist James Hansen joins a protest to highlight the dangers of climate change in Coventry, England. (AFP)


Climate scientists are canaries in the coal­mine – highly attuned to sense danger before we blunder into it. For decades, various researchers have issued calamitous warnings about climate change. But was there a moment when science collectively, definitively dropped off the perch?

During the 1990s, scientists were still debating the most basic assertions of climate change science.
Was the world indeed warming? Consensus grew slowly, but many scientists remained undecided.

Two bold scientific statements book-ended the decade: Professor James Hansen’s statement to the United States Senate in 1988 and the 1999 hockey stick graph.

The two were influential in bringing climate change into the public consciousness. Yet both were accused of using unproven methods to reach their conclusions, damaging the credibility of climate science and paving an easy road for denialism.

Hansen, head of Nasa’s Goddard Institute for Space Studies, told the US Senate’s energy and natural resources committee in 1988 that his research on human-induced global warming was unequivocal. “The greenhouse effect has been detected and it is changing our climate now,” he said.

“Hansen was a scientist who bumped right up against the edge of activism and a lot of scientists have been very uncomfortable going over into that. And rightly so … if you’re seen too much as an activist, then people won’t trust your science,” said Marshall Shepherd, 2013 president of American Meteorological Society.

The US National Climate Assessment, released last week, echoed Hansen’s words 26 years later: “Climate change is already affecting the American people.”

Lack of nuance
But even the climate assessment, built as it was on the work of 800 scientists, has been criticised for a lack of nuance. To maintain credibility, climate science must walk the narrow ledge between conservatism and activism.

Some scientists believe the hockey stick graph, published in 1999, dangled both feet over this edge. Michael Mann, Raymond Bradley and Malcolm Hughes used data gathered from tree rings, lake sediments, ice cores and corals to recreate the global temperature over the past 1 000 years. The image they produced was a startling visual communiqué of the world’s postindustrial warming trend. It was featured prominently in the 2001 report of the Intergovernmental Panel on Climate Change (IPCC).

But Mann et al’s willingness to use unproven methodology irked some scientists, including climate professor Mike Hulme of Kings College London: “I don’t think it was seminal for scientists. To me that was never a decisive interventional piece of evidence. The data was absolutely scanty.”

Shepherd disagrees. “I think it would be characterised as a watershed moment in climate science,” he said, although he recognises it as “one of the singular most polarising graphs or scientific pieces of data that exist”.

The problem for Mann and Hansen is that the world wants to see all the canaries keeling over together, a clear public moment of unequivocal proof. Disagreements are latched on to as evidence that the scientific process is flawed, fuelling the denial movement.

Consensus on climate change built incrementally during the 1990s until, by the time the 2001 IPCC report came out (with the hockey stick graph in it), there were very few scientists who felt uncomfortable attributing some climate change to human activity.

Notably absent from the consensus building of the 1990s were the voices of climate scientists from developing countries, says Chandra Bhushan, deputy director of the Centre for Science and Environment in Delhi. Mostly, this was because the research was simply not happening. The imbalance persists to this day.

Bhushan says climate scientists from the Global South “still play a very little role in developing consensus on climate change negotiations”. The latest IPCC report drew more than 90% of its research material from developed countries.

Scientists participate in the compiling of IPCC reports with funding from their governments, meaning wealthy countries can afford to participate more in the process. This has the effect, Bushan argues, of politicising the reports, which he says have focused unduly on the impacts of climate change on the developed world. – © Guardian News & Media 2014

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