I hope everyone had a fun and relaxing Christmas. Here’s a book I’ve been meaning to review for a while.

The worst part of the recent book by NASA climatologist James Hansen is, undoubtedly, the subtitle. The truth about the coming climate catastrophe and our last chance to save humanity – really? That doesn’t sound like the intrinsic, subdued style of Dr. Hansen. In my opinion, it simply alienates the very audience we’re trying to reach: moderate, concerned non-scientists.

The inside of the book is much better. While he couldn’t resist slipping in a good deal of hard science (and, in my opinion, these were the best parts), the real focus was on climate policy, and the relationship between science and policy. Hansen struggled with the prospect of becoming involved in policy discussions, but soon realized that he didn’t want his grandchildren, years from now, to look back at his work and say, “Opa understood what was happening, but he did not make it clear.”

Hansen is very good at distinguishing between his scientific work and his opinions on policy, and makes no secret of which he would rather spend time on. “I prefer to just do science,” he writes in the introduction. “It’s more pleasant, especially when you are having some success in your investigations. If I must serve as a witness, I intend to testify and then get back to the laboratory, where I am comfortable. That is what I intend to do when this book is finished.”

Hansen’s policy opinions centre on a cap-and-dividend system: a variant of a carbon tax, where revenue is divided evenly among citizens and returned to them. His argument for a carbon tax, rather than cap-and-trade, is compelling, and certainly convinced me. He also advocates the expansion of nuclear power (particularly “fourth-generation” fast nuclear reactors), a moratorium on new coal-generated power plants, and drastically improved efficiency measures.

These recommendations are robust, backed up with lots of empirical data to argue why they would be our best bet to minimize climate change and secure a stable future for generations to come. Hansen is always careful to say when he is speaking as a scientist and when he is speaking as a citizen, and provides a fascinating discussion of the connection between these two roles. As Bill Blakemore from ABC television wrote in correspondence with Hansen, “All communication is biased. What makes the difference between a propagandist on one side and a professional journalist or scientist on the other is not that the journalist or scientist ‘set their biases aside’ but that they are open about them and constantly putting them to the test, ready to change them.”

Despite all this, I love when Hansen puts on his scientist hat. The discussions of climate science in this book, particularly paleoclimate, were gripping. He explains our current knowledge of the climatic circumstances surrounding the Permian-Triassic extinction and the Paleocene-Eocene Thermal Maximum (usually referred to as the PETM). He explains why neither of these events is a suitable analogue for current climate change, as the current rate of introduction of the radiative forcing is faster than anything we can see in the paleoclimatic record.

Be prepared for some pretty terrifying facts about our planet’s “methane hydrate gun”, and how it wasn’t even fully loaded when it went off in the PETM. Also discussed is the dependence of climate sensitivity on forcing: the graph of these two variables is more or less a parabola, as climate sensitivity increases both in Snowball Earth conditions and in Runaway Greenhouse conditions. An extensive discussion of runaway greenhouse is provided, where the forcing occurs so quickly that negative feedbacks don’t have a chance to act before the positive water vapour feedback gets out of control, the oceans boil, and the planet becomes too hot for liquid water to exist. For those who are interested in this scenario, Hansen argues that, if we’re irresponsible about fossil fuels, it is quite possible for current climate change to reach this stage. For those who have less practice separating the scientific part of their brain from the emotional part, I suggest you skip this chapter.

I would recommend this book to everyone interested in climate change. James Hansen is such an important player in climate science, and has arguably contributed more to our knowledge of climate change than just about anyone. Whether it’s for the science, for the policy discussions, or for his try at science fiction in the last chapter, it’s well worth the cover price.

Thoughts from others who have read this book are welcome in the comments, as always.