Our top climate scientist was interviewed by Newsweek‘s Science Editor last week. Sharon Begley talked to Hansen “on the eve of the publication of his first book, Storms of My Grandchildren, which he finished while recovering from treatment for prostate cancer and which will be published in December.”

SB:  Last week, someone leaked emails obtained by hacking into the server at the Climate Research Unit at the University of East Anglia. Activists who have long denied the reality of climate change say they show that climatologists have engaged in a grand conspiracy to manufacture a case that global warming is occurring due to human activities. Do the hacked emails undermine the case for anthropogenic climate change?

JH:  No, they have no effect on the science.  The evidence for human-made climate change is overwhelming.

SB:  Do the emails indicate any unethical efforts to hide data that do not support the idea of anthropogenic global warming or to keep contrary ideas out of the scientific literature and IPCC reports?

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JH:  They indicate poor judgment in specific cases. First, the data behind any analysis should be made publicly available.  Second, rather than trying so hard to prohibit publication of shoddy science, which is impossible, it is better that reviews, such as by IPCC and the National Academy of Sciences, summarize the full range of opinions and explain clearly the basis of the scientific assessment. The “contrarians” or “deniers” do not have a scientific leg to stand on.  Their aim is to win a public relations battle, or at least get a draw, which may be enough to stymie the actions that are needed to stabilize climate.

And here’s more from Hansen on the science:

SB:  Policymakers who deny the threat of climate change cite the research of Richard Lindzen of MIT and other scientists, who question the link between carbon dioxide and global warming — as the last head of NASA, Michael Griffin, also did. As long as there remains this scientific dispute, why should policy makers act?

JH:  These contrarians are not having much effect. None of the major countries are denying the problem anymore, though in the U.S. these contrarians are still widely heard, and when it comes to passing a bill in Congress they may still be an obstacle.

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SB:  In the 1980s scientists worried about a doubling of pre-industrial levels of carbon dioxide, to 550 parts per million. Then 450 started to look like a problem. Now you and others say that 350 is dangerous, and we’re already at 387. What did climatologists learn that caused them to lower the estimate of dangerous CO2 levels?

JH:  The new information came from observations of how the system is responding to 387ppm and to more detailed information on how earth responded in the past to different atmospheric compositions. For instance, we see that the ice sheets are not stable at 387ppm; the Greenland and Antarctic ice sheets are losing mass even with current warming. The Greenland ice sheet had been losing between 150 and 200 cubic kilometers a year in 2002, and now is losing almost 300 cubic kilometers a year. Antarctica had been losing less than 100 cubic kilometers a year, and is now losing more than 150, so it seems like we’re heading into a period of much more rapid ice sheet loss. Also, in the arctic we’ve lost 40 percent of the sea ice in the warm season, and that will soon be 100 percent. Mountain glaciers are retreating rapidly  and could be gone in 50 years. These are not model results but observations: 387ppm is already too high, and 450ppm will be far worse.

SB:  In Storms of My Grandchildren, you describe climate tipping points. What are some and why are they so dangerous?

JH:  Things like methane hydrates on the continental shelf and the tundra: as they warm up they release their methane [which is a greenhouse gas], which we’re already seeing in the tundra and elsewhere. Tipping points are so dangerous because if you pass them, the climate is out of humanity’s control: if an ice sheet disintegrates and starts to slide into the ocean there’s nothing we can do about that.

SB:  What caused you to move beyond research and become an outspoken advocate for addressing climate change?

JH:   The realization that there was a gap between what had become clear scientifically and what policymakers knew. Then, when I wrote papers and gave talks on climate change, it became clear that the political system just didn’t want to react to this. Scientists have to help politicians connect the dots.

Yes, I skipped over what Hansen had to say about climate policy, which includes puzzling things like “What’s needed is putting a price on carbon, not cap-and-trade.” He is a world-class expert on the science but not on the policy, and I’ve made my disagreements with him clear many times in the past (see here and here and here).

I’ll review Hansen’s disappointing book next week when it is out. The science in the book is sensational, of course, but you can get most of that online (see links below). What is the most disappointing about the book is not his policy suggestions, which we’ve seen many times now, but his surprisingly uninformed discussion of efficiency and renewables.

Hansen is not an energy expert, and while he can opine on energy matters all he wants, the fact is he and the rest of the climate science community has not yet succeeded in “Job One” — explaining the science clearly and persuasively to the public in the face of the well organized disinformation campaign.

My unsolicited advice to our top climatologist is to refocus your efforts at communicating the science — on which you are an unparalleled expert.