A Harvard Professor, now the White House’s top science advisor, and the Brisbane, Australia, editor of SkepticalScience.com provide two valuable examples of constructive engagement with climate ‘skeptics.’

Among the lessons learned over the past several decades of climate change dialog:

There are lots of ways to speak with climate “skeptics.” And even more ways, it turns out, to mis-speak. Not speaking at all is the preferred option of some serious climate scientists, many of whom have given up in frustration over their own and their colleagues’ past shortcomings and, more importantly, over their adversaries’ tactics. Or else they simply feel their science-based arguments just can’t be reconciled with what they see as the innuendo- and rhetoric-laden themes constantly played back. Sometimes, however, that conspicuous reticence generates criticisms, well- or ill-founded, of an unwillingness to engage.

But there are exceptions, and they can offer valuable insights. Think here of the “From the mouths of babes, oft-times come gems” rubric.

Well, they’re not “babes,” but in this case a seasoned and highly respected climate scientist and a proven and innovative climate science communicator. Their exchanges with individuals whom they had never met offer constructive lessons.

Holdren ‘Swamped’ … But Not Too Busy to Engage …

The one case goes back several years, but it’s only recently come to light. It involves then-Harvard University Professor John P. Holdren, now President Obama’s director of the White House Office of Science and Technology Policy. The exchange actually started in September 2003, with an e-mail from Nick Schulz, the editor of the climate-doubtful TechCentralStation website. Schulz wanted to know how Holdren felt about the “hockey stick” research work headed up by climate scientist Michael Mann.

“Swamped with other commitments,” Holdren took nearly a month to initially respond. But when he did so, he replied in detail and with verbal clarity. He emphasized in a “PS” note at the end of his long and detailed reply: “I have provided this response to your query as a personal communication, not as fodder for your selective excerpting on your website or elsewhere.” He asked that his response, if repeated, be communicated “in its entirety.”

A few days later, Schulz replied with a “burden of proof” question, suggesting different standards were being applied to Mann’s research compared with that of two well-known “skeptics” — in this case, Willie Soon and Sallie Baliunas and their research.

Holdren’s reply came the next day, again at considerable length, opening with “You ask good questions.” The whole exchange — through Holdren’s “I hope you have found my responses to be of some value. I now must get on with other things.” is now online at a White House site.

SkS Editor Cook: There is No ‘Our Evidence/Their Evidence’

A second and more recent example comes from a June 2011 e-mail inquiry directed to Australian John Cook, editor of skepticalscience.com.

“I read your skeptic v denier thing,” the questioner wrote. “I will read anything by anyone.”

“Others make the exact opposite statement with the same veracity, but others provide proof while you do not.” The questioner in this case challenged Cook’s assertions on shrinking Arctic and Greenland ice.

“I have looked at both sides of this argument for 20 years, and I must say the warmists are wrong,” he wrote. “The warmists are losing based on the facts alone.”

It was the kind of question that Cook — whose work on his website comes along with a full-time home office day job doing other things — might well have cold-shouldered. But he didn’t.

“Thanks for your message,” he opened with his June 5 response. He took a stab at the “skeptic vs denier thing” the questioner specifically asked about, saying “the key point … is we need to look at the full body of evidence in order to gain a proper understanding of climate.”

… Only ‘the Full Body of Evidence’

“There is no ‘their evidence’ vs. ‘our evidence’ — there is only the full body of evidence.”

Comparing, for instance, two images of Arctic sea ice extent doesn’t cut it, Cook wrote. “You need to look at all the data on Arctic sea ice, not just two instantaneous moments in time.” The full data set, he wrote, “shows a steadily declining long-term trend, but even more telling is the total amount of Arctic sea ice (eg-volume) — the sea ice is getting thinner and volume reached record low levels in 2010.”

Cook, in his reply, pointed to cherry-picking of data as suggesting interior Greenland ice is growing, but added that ice loss at the edges “far outweighs” gains inland. “In fact, it’s losing around 300 billion tonnes per year and is now one of the greatest contributors to sea level rise,” he wrote.

Though “some glaciers are growing now,” he continued, “the vast majority of glaciers are retreating” … and at an accelerating rate.

“To understand what’s happening with sea level rise, we need to look at more than a single location or a few locations,” Cook wrote. Research across the planet, tidal gauges and satellites “provide[s] a consistent answer — sea level rise has been accelerating over the past century.”

Cook concluded his reply* by addressing the “common argument” from climate skeptics that atmospheric CO 2 concentrations in the past have been higher than they are now. Those emphasizing that point “never mention … that as you go further back in the past, the sun is gets (sic.) steadily cooler,” he wrote, asking that the questioner “feel free to point to an example to prove me wrong” on that point.

“If it was just the sun driving climate, the Earth would be a frozen iceball in the deep past — it’s only the warming effect from those high levels of CO 2 that keep the Earth from freezing,” he wrote. “This is a very good example of the wrong conclusions you can arrive at when you don’t consider the full picture.”

“Hope that helps,” Cook concluded, “would be happy to answer any further questions you might have.”

*The initial e-mail inquiry to John Cook was channeled by the questioner through The Yale Forum, which in turn passed it on to Cook. Cook, in his reply, copied The Yale Forum and authorized use of the exchange for this article.