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Witness, Preacher or Prophet?
on October 3, 2013
James Hansen tells us, “My role is that of a witness, not a preacher.” In the late 1980’s he was one of the first major climate scientists to publicly state that anthropogenic global warming was a serious problem. While the idea was not new, he was willing to draw firm conclusions from evidence that most other scientists did not consider to be sufficiently certain. His predictions turned out to be reasonably accurate. Now he is trying to repeat this accomplishment, making even bolder predictions from less certain evidence. In this book we witness a distinguished scientist taking on the role of not just preacher, but prophet, going well beyond the majority of his colleagues in his view of the consequences of climate change.
The main storyline is Hansen's interactions with government, embedded with lengthy attempts to explain the underlying climate science. His exploration of policy and interaction with government institutions is much better than his scientific explanations. To his credit, Hansen does not fit the usual environmentalist stereotype. He does not endorse voluntary poverty, nor does he think that conservation and renewable energy can provide the needed energy. Instead, he thinks that nuclear energy is the only realistic option. He states, "The antinuke advocates are so certain of their righteousness that they would eliminate the availability of an alternative to fossil fuels, should efficiency and renewables prove inadequate to provide all electricity. What if the utility executives are right, and we must choose between coal or nuclear for base load power? Even if renewables are sufficient to produce the electricity needed by the United States, what about India and China. It's one world, and we have to live with pollution from India and China."
He rightly scorns "government greenwash" policies that pretend to reduce carbon dioxide production. Instead, he advocates "fee and dividend", better known as a carbon tax. All fuels that produce carbon dioxide are taxed, and the money is redistributed to the population. This avoids government-knows-best micromanagement of the energy sector, and gives incentives for industry and consumers to reduce carbon dioxide use.
He slams the cap-and-trade schemes favored by governments, which pretend to the public that someone else will pay the costs. Governments, influenced by lobbyists, arbitrarily decide caps on emissions. The trade part will be controlled by the same people who brought us the banking crisis. They will make their fortune no matter what actually happens to carbon dioxide production.
Hansen does a surprisingly poor job explaining his profession. One would expect an introduction to teach the reader how the climate works. The usefulness of global average temperature, the meaning of climate sensitivity, the role of uncertainty should all be explained. There is none of this, or even any sense of the wonder and beauty of science. Instead he launches directly into rather technical dialog, interspersed with exhortations to the poor reader to pay attention, this is important. I doubt the average reader will understand any of it, and will simply skip to Hansen’s conclusion of what it all really means. It is unclear exactly who is the intended audience. The general public will appreciate the policy writing but will not be able to follow the science. Technical readers will not be impressed by the lack of references provided, which are mainly to his own papers, not always published in peer reviewed journals.
As for the science itself, Hansen says that the best evidence for understanding climate is based on paleoclimate - the study of the climates of the past. He explicitly states that climate models cannot be used to determine climate sensitivity, which is the response of the climate to changes in carbon dioxide levels. In the chapter “A Visit to the White House” he estimates this climate sensitivity by comparing the difference in climate between the previous ice age and today. This approach uses the Earth itself as a “computer model” which includes all the physics that affect climate, whether we presently understand them or not. This is good, but then he does a quick calculation based on only two of the many feedbacks, to get a climate sensitivity of 3 degrees for every doubling of carbon dioxide. While this kind of technical detail may impress (or intimidate) the casual reader, one familiar with the subject knows that the value is reasonable but the precision is misleading. Note that today’s world is very different from that of the last ice age. Climate sensitivity is now lower because there is much less ice at low latitudes, which reduces a major feedback. It would be better to explain at a more basic level what an ice age is about, and what causes the transition to an interglacial climate like the one we are in now. Demonstrate that small changes caused by variations in the Earth’s orbit led to large changes in climate, so changes we make to greenhouse gases in the atmosphere may also have significant effects. Then provide an appendix or decent references for someone who wants more detail. In this case the chapter summary did not even reference the relevant paper.
In “Target Carbon Dioxide” he discusses the geological event known as the Paleocene-Eocene Thermal Maximum (PETM) that occurred 55 million years ago. We know that a large amount of organic carbon entered the atmosphere, causing around five degrees of global warming that lasted thousands of years. The most likely, but not certain, source of the carbon is methane hydrates under the ocean floor. Hansen then tells a great story about how the methane was released by warming oceans, and how the same methane hydrate reservoir is now fully recharged and ready to blow. He does not mention that scientists who study the issue see no reasonable mechanism for how they could be released in large quantities by any conceivable human caused global warming. Remember today’s ocean is much colder than 55 million years ago, when alligators swam in the Arctic Ocean. Again, no real references are given to support his statements. The PETM event gives us a useful example of relatively rapid global warming, but it is not well understood yet, so simplistic conclusions should not be drawn.
In “Dangerous Reticence” he talks about trying to publish his paper “Can We Defuse the Global Warming Time Bomb” in Scientific American, saying they wanted to change it to conform to the standard IPCC view. Then he says, “with the paper’s extensive criticisms of the IPCC, there was no realistic change of publishing it in a regular scientific journal – most of the likely referees for the paper were contributing authors of IPCC.” This is exactly the same claim that global warming skeptics like to make. I do not know how much of a real problem there is with conformism in mainstream climate science. I think it is more likely that these works from both sides really fail to meet scientific standards, and whining about bias is a great excuse. The chapter title refers to his perception that scientists are dangerously reticent to tell the public what they really know. I suggest instead there is a benign reticence to publicly criticize a well-known scientist who has lost his objectivity, knowing there is a legion of unscrupulous “skeptics” who will take advantage of anything to push their belief that climate change is not real.
The final two chapters not only describe a disaster, they are a disaster. In “The Venus Syndrome” he claims that burning all the available fossil fuels will cause a runaway greenhouse effect like on Venus. This seems to be based on a simulation with a climate model. These models, as Hansen himself points out, are challenged to achieve what they are intended to, and cannot be relied upon to determine climate sensitivity. But he then tortures the model by running it under conditions for which it was not designed to handle. Hansen’s claims have not been published in any peer reviewed journal, so they have little credibility. Those scientists who are experts in the field categorically state that a human induced runaway greenhouse effect is not possible. The final chapter goes completely off the rails, including a hokey science fiction story about aliens coming to Earth to escape their ravaged planet, only to find the Earth wrecked by the human induced runaway greenhouse effect. Then he asks people to indulge in the environmentalist version of greenwashing – pointless demonstrations against coal plants and pipelines. This is great for making people feel they are “taking action” while ignoring the real work of building a sustainable energy system.
Several times in the book Dr. Hansen reports his encounters with his nemesis, atmospheric scientist Richard Lindzen of MIT. While they both agree on the basics of climate science, Lindzen soothes us with assurances about negative feedbacks such as reflective clouds or masses of warm moist air rising from the tropics, while Hansen scares us with methane time bombs and a runaway greenhouse effect. In science it is useful to constantly challenge the current theories. But they both present their conclusions as revealed truth to their legions of uncritical believers, the deniers and the doomsters respectively. Hansen’s unfortunate transition from respected scientist to prophet of doom is only going to further polarize the climate change debate. Because Hansen does not clearly distinguish between his own and the mainstream view, and does not discuss uncertainty, the critical reader will have a hard time knowing what to believe. This book is a lost opportunity to appraise the public on the current state of climate science.