Monday, November 30, 2015

‘I was tossed out of the tribe’: climate scientist Judith Curry interviewed

For engaging with sceptics, and discussing uncertainties in projections frankly, this Georgia professor is branded a heretic

By David Rose in The Spectator. Excerpts:
"Her record of peer-reviewed publication in the best climate-science journals is second to none, and in America she has become a public intellectual. But on this side of the Atlantic, apparently, she is too ‘challenging’. What is troubling about her pariah status is that her trenchant critique of the supposed consensus on global warming is not derived from warped ideology, let alone funding by fossil-fuel firms, but from solid data and analysis.

Some consider her a heretic. According to Professor Michael Mann of Pennsylvania State University, a vociferous advocate of extreme measures to prevent a climatic Armageddon, she is ‘anti-science’."

"Warming alarmists are fond of proclaiming how 97 per cent of scientists agree that the world is getting hotter, and human beings are to blame. They like to reduce the uncertainties of climate science and climate projections to Manichean simplicity. They have managed to eliminate doubt from what should be a nuanced debate about what to do.

Professor Curry, based at the Georgia Institute of Technology in Atlanta, does not dispute for a moment that human-generated carbon dioxide warms the planet. But, she says, the evidence suggests this may be happening more slowly than the alarmists fear."

"This debate will be conducted on the basis that there is a known, mechanistic relationship between the concentration of carbon dioxide in the atmosphere and how world average temperatures will rise.

Unfortunately, as Curry has shown, there isn’t. Any such projection is meaningless, unless it accounts for natural variability and gives a value for ‘climate sensitivity’ —i.e., how much hotter the world will get if the level of CO2 doubles. Until 2007, the UN Intergovernmental Panel on Climate Change (IPCC) gave a ‘best estimate’ of 3°C. But in its latest, 2013 report, the IPCC abandoned this, because the uncertainties are so great. Its ‘likely’ range is now vast — 1.5°C to 4.5°C."

"According to Curry, the claims being made by policymakers suggest they are still making new policy from the old, now discarded assumptions. Recent research suggests the climate sensitivity is significantly less than 3˚C. ‘There’s growing evidence that climate sensitivity is at the lower end of the spectrum, yet this has been totally ignored in the policy debate,’ Curry told me. ‘Even if the sensitivity is 2.5˚C, not 3˚C, that makes a substantial difference as to how fast we might get to a world that’s 2˚C warmer. A sensitivity of 2.5˚C makes it much less likely we will see 2˚C warming during the 21st century."

"the sensitivity value may still lower, in which case the date when the world would be 2˚C warmer would be even further into the future. On the other hand, the inherent uncertainties of climate projection mean that values of 4˚C cannot be ruled out — but if that turns out to be the case, then the measures discussed at Paris and all the previous 20 UN climate conferences would be futile. In any event, ‘the economists and policymakers seem unaware of the large uncertainties in climate sensitivity’, despite its enormous implications.

Meanwhile, the obsessive focus on CO2 as the driver of climate change means other research on natural climate variability is being neglected. For example, solar experts believe we could be heading towards a ‘grand solar minimum’ — a reduction in solar output (and, ergo, a period of global cooling) similar to that which once saw ice fairs on the Thames. ‘The work to establish the solar-climate connection is lagging.’"

" ‘I think that by 2030, temperatures will not have increased all that much. Maybe then there will be the funding to do the kind of research on natural variability that we need, to get the climate community motivated to look at things like the solar-climate connection.’"

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