PBS ran a two-hour NOVA special on global warming during the week of Earth Day 2000. While much could be said about the program’s balance or lack thereof, the documentary is remarkable for another reason: PBS interviewed the wrong scientist.
The documentary featured a scientist who was not an expert in the subject he was describing, while the real expert sat in an office just down the hallway. The real expert disagrees with the scientist PBS interviewed. Had PBS interviewed the right person, the program may have left a much different impression on the minds of the many people who watched it.
“Surprises” in global warming
During the first hour of the program, a staple argument used by alarmists was raised: “surprises” caused by man’s intervention with climate. Alarmists talk about surprises because the Intergovernmental Panel on Climate Change (IPCC) has not documented that human activities to date have caused weather to become more extreme.
A popular alarmist surprise scenario is that climate change will result in a cessation of the “conveyer belt” deep-water circulation system. Professor Ronald Prinn, a featured scientist on the PBS program, said “a shutdown of just that circulation” could lead to “glaciers on land that was previously vegetation covered.” “Paradoxically,” he said, “a warming in that case would lead to a catastrophic cooling in some parts of the world.”
That thesis had been the cover story of Atlantic Monthly in early 1998, when William Calvin (bylined as a “theoretical neurophysiologist”) postulated that fresh water from melting ice and increased rainfall, both from the enhanced greenhouse effect, would make ocean water less salty (less dense), inhibiting deep-water circulation. The global-warming-to-global-cooling hypothesis was also pushed in the New York Times by the dean of alarmist reporters, William K. Stevens.
Some time ago I asked Dr. Richard Lindzen, the Sloan Professor of Meteorology at MIT, to evaluate this hypothesis. He responded:
One cannot observe the “conveyer belt” even in today’s ocean circulation. [MIT’s] Carl Wunsch has been especially outspoken on this. So has Bill Schmidt, senior scientist at Woods Hole Oceanographic Institution. However, even if the conveyer belt were a reasonable depiction of the thermohaline circulation, we wouldn’t know if cooling or warming would be more likely to trigger a change. Thus any policy could be the “wrong” policy. Note that the paleo evidence points to greater changes in the presence of major glaciation.
The wrong man
Prinn, the man PBS chose to present the “conveyer belt” thesis, is the TEPCO Professor of Atmospheric Chemistry at MIT. He is not an ocean specialist.
The real expert was just down the hall from Prinn: Dr. Carl Wunsch. Wunsch is the Cecil and Ida Green Professor of Physical Oceanography and director of the Department of Earth, Atmospheric and Planetary Sciences at MIT. Elected to the National Academy of Sciences, Wunsch is among the world’s top scientists in the field of physical oceanography.
I asked Wunsch whether he thought the reversing conveyer-belt scenario is a reasonable hypothesis, and whether a warming or cooling of the water would be more likely to precipitate a change that could be problematic. Wunsch’s complete response, which is worth close reading, follows:
It’s a somewhat frustrating business. The ocean does move around heat and salt, but it does so via an integral over very complex flows varying in space and time, which doesn’t look anything at all like a “global conveyor belt.” The [Wallace] Broecker picture of a conveyor belt is perhaps a metaphor for the real fluid flow, but it has been completely confused in many people’s minds with the actual situation.
That the ocean circulation has likely been radically different in the past is true. But understanding what happened is probably impossible by thinking of the real system as a kind of a bench top toy. Some people appear to think they can integrate the equations of motion of an extraordinarily complex, rotating stratified turbulent fluid in their heads and produce the right answer. (And one can’t leave out the atmosphere.) I wish I had those kind of mental powers.
All I’m willing to say is that climate has changed, and will change again and that the ocean circulation will change too. At the present level of understanding we have various interesting hypotheses, and a set of just so stories.
When I later asked Wunsch if I could publicize his responses verbatim, he said, “You can share this with anyone you like. I’ve never made any secret of my views, although I’ve also done nothing to publicize them.”
Learning from mistakes
Climate-oceanic interactions are clearly a complicated subject that the science community is still trying to understand. The PBS story illustrates how politicized science has spoiled an open, accurate discourse in the climate change debate.
Why did PBS interview the wrong person to set up an alarmist scenario? How many experts like Wunsch are lying low in the debate, while others such as Broecker (the father of the thermohaline scare) or even Prinn oversimplify the situation and attract the attention?
Why is the view that we know too little in this area so out of fashion? The surprise trigger with this surprise scenario could be just the opposite of what the alarmists postulate, making anthropogenic warming a positive “surprise.”
The PBS episode does not inspire confidence in the media. But with just about everything getting better in an everyday march of life, what must news specials do to get folks to tune out the ballgame or put down their book? To ask the question may be to answer it.
Robert L. Bradley, Jr. is president of the Institute for Energy Research and author of the just-released energy primer, Julian Simon and the Triumph of Energy Sustainability.