Monday, July 4, 2011

Book Review: 'Storms of My Grandchildren' by James Hansen

Storms of my Grandchildren (2009)
James Hansen (1941-)

320 pages

In writing Storms of my Grandchildren, James Hansen makes a clarion call for action to reduce greenhouse gas emissions, concluding that “continued exploitation of all fossil fuels on Earth threatens not only the other millions of species on the planet but also the survival of humanity itself --- and the timetable is shorter than we thought.” (p. IX).

Hansen is a physicist with a background in both space and earth sciences. Starting in the late 60’s as a graduate student he spent a decade studying the planet Venus and its climate, before turning his focus in 1978 to Earth, curious about what impact the rapidly changing composition of our atmosphere would have on our climate. He has worked at both universities and as director of the NASA Goddard Institute for Space Studies. In 1988 he testified before the Senate that “with 99 percent confidence … Earth was being affected by human-made greenhouse gases, and the planet had entered a period of long term warming.” (p. XV)

Over the past few years, Hansen has become convinced, based on an increasingly accurate understanding of Earth’s historical climate, the accelerating rate of increase of greenhouse gases in the atmosphere today, and the changes observed in Earth’s biosphere, that we driving the Earth to a climate tipping point even more rapidly than previously thought, a point which, once past, we will be powerless to return across, and which has the potential to make the world a dramatically more difficult place to live in as short a time as the end of this century, and even uninhabitable in the not too distant future beyond that. Seeing no urgency to action among politicians or the general public, and fearing for the future of his, “and all the world’s grandchildren” (p. 5), Hansen wrote this book, to tell, as he says in the subtitle, “The truth about the coming climate catastrophe and our last chance to save humanity.”

In a never dull, often entertaining and occasionally scary 320 pages, Hansen fills in the details around a simple chain of observations: greenhouse gases are changing the Earth’s atmosphere; historical data from over many millions of years give clear indications of the disastrous effects the increase in greenhouse gases will have on Earth’s climate; the only way to avoid the currently inevitable disaster is to phase out coal burning by 2030, starting immediately; and the only way to replace coal-based energy in the short-term, until renewable forms of energy can fill the void, is to use nuclear energy.

In between fleshing out the details of each of these observations, Hansen also describes his role in the political and scientific discussions on the topic over the past couple of decades. He makes clear throughout the book his distaste for having to become involved in the political aspects, preferring to stay focused on the scientific work. Climate change contrarians often accuse scientists who support the idea of global warming as ‘in it for the funding’, but it is clear from Hansen’s book, as well as coverage in the media over the years (e.g., Climate Expert Says NASA Tried to Silence Him, in The New York Times), that Hansen, particularly in his role as a NASA administrator, has had a more difficult time of it because of where the science has led him in his views. Describing himself as politically conservative, he displays no partisanship in his disappointment with politicians of both parties. The insights he provides into what occurs in the interactions between scientists and politicians makes for interesting reading --- though there are no shocking revelations to anyone having followed the debates in the media over the years.

What Hansen does particularly well in the book is describe the science of climate change. He begins by defining climate forcing agents, changes that can cause Earth to have an energy imbalance: a negative climate forcing agent causes the Earth to radiate into space more energy than it absorbs (= cooling), while a positive climate agent causes Earth to absorb more energy than it radiates into space (= heating). He then describes the significant, known climate forcing agents (natural and man-made, positive and negative), scientists understanding of the magnitude and uncertainty of each of them, and the mechanism by which they act on the Earth’s energy balance.

Climate forcing agents and the mechanisms by which they affect Earth’s energy balance are relatively well-understood, even if the precise magnitude of each is not known, as shown in the error bars in Figure 1. Less well-understood is climate sensitivity, which Hansen defines as the amount of global temperature change in response to a specified climate forcing agent. For example, greenhouse gases are a climate forcing agent --- an increase in their amounts causes a known amount of heating of the Earth --- but how much temperature rise will a given amount of Greenhouse gases ultimately cause?

Hansen lists two methods of estimating what the climate sensitivity to greenhouse gases and other climate forcing agents might be: 1) Global Climate Models; and 2) the Paleoclimate Record. He spends little time discussing Climate Models, characterizing them as having some useful applications, but as not accurate enough to be effective at estimating climate sensitivity to forcing agents. His preferred method, the one that he spends much of the book describing, is the Paleoclimate Record. Ice core samples allow researchers to estimate temperature and atmospheric composition going back over 400,000 years, while ocean floor core sample allow researchers to look back even farther, tens of millions of years into the past. How these core samples reveal Earth’s climate history, and what that history tells us about the potential impact of the changes we are making to Earth’s atmosphere are a fascinating story that Hansen manages to present at a level that an interested layman with a little background in science can understand. (For those less interested in the scientific details he at times conveniently suggests points where a reader can skip ahead a few paragraphs or pages).

As he lays out the findings from the past couple of decades of analysis of the Paleoclimate Record, he ranges over a variety of topics, some interesting, some scary: our understanding of why the ice ages occurred and why another one can never occur again as long as mankind survives; how scientists estimate the potential effects of man-made climate forcing agents of the present day based on the effects due to the same forcing agents occurring naturally in the past; and the threat of the melting of frozen methane in a (geologically) short time and its potential to make the Earth uninhabitable. These topics and more Hansen discusses at length and with a level of scientific detail that provides the reader a decent level of understanding of the science as it stands today. One finishes with an appreciation for what is known more precisely, and where there is still uncertainty in the science.

Not just focusing on the problems, Hansen also suggests solutions that can reduce the risk of reaching a dangerous tipping point that could lead to the ‘climate catastrophe’ to which he believes our current course is leading us.

He repeatedly writes that the world must move to zero coal burning emissions by 2030, decreasing linearly from 2010 --- a goal that as of the current year 2011 we are already falling behind --- and that we must not exploit all of the potential gas and oil reserves. To encourage the transition from coal, oil and gas as sources of energy, he suggests the need to make them more expensive, both as motivation to improved levels of efficiency in energy use, and to make other sources of energy friendlier to investment. He spends several pages describing the ineffectiveness of cap-and-trade as an approach to do that, and states his preference for what he describes as a much simpler approach, a fee-and-dividend system. In a fee-and-dividend system, coal, oil and gas are taxed at their point of entry into this country (whether from underground or by transport), and the collected funds are then divided equally in checks to all the country’s legal residents.

Hansen also makes a strong case for nuclear power, while acknowledging the current antipathy of many in the environmental movements to this form of energy. He is convinced that without nuclear power, there will be no possibility of reducing our use of coal to zero. He makes a pitch for what he calls fourth generation, fast breeder reactors, a technology that he states has been proven in the laboratory, is safer to operate and produces waste with much shorter lifetimes than current reactors (a couple hundred years instead of 10,000 years). He defends nuclear energy as an approach to allow us the time to make the long transition to ‘green’ energy sources, by countering that the alternative --- continuing to burn coal --- will lead to certain climate catastrophe. He also makes the interesting point that it is estimated that many more people die each year from pollution due to coal burning, than die from radiation due to nuclear power plants and their waste.

Some of the details of the science aside, the book is a comfortable read. Hansen takes a conversational approach, sounding throughout like the grandfather scientist he is, apologizing to the reader when he fears they might find him too harsh in his condemnation of a particular person, and at times wearing his exasperation with politicians and others on his sleeve. A small quibble with the book is that Hansen mixes the discussion of his political experiences right in with the scientific picture he builds. This does spice up the story a bit, keeping it from becoming a dry, extended scientific research paper, but it can be a little frustrating at times, to have the building of a scientific explanation suddenly put on hold for several pages as he describes yet another example of his interactions with politicians who at best can’t, and at worst won’t, understand what the scientific consensus tells them. Overall, however, Storms of my Grandchildren represents a fascinating introduction to the current state of climate change science --- if also a scary, wake-up call as politicians discuss the exploitation of tar sands, and countries world-wide continue to build more coal-fired power plants.

Other reviews / information:

Hansen maintains a website with updated figures from the book.

Up one level at the same website leads to links to other data on climate science.

Other of my book reviews: FICTION and NON-FICTION