Photos of James Hansen’s grandchildren have appeared not infrequently in his presentations in recent years. He obviously delights in them. But he also fears for them. The nature of that fear is spelt out in his newly published book Storms of my Grandchildren with its foreboding subtitle The Truth About the Coming Climate Catastrophe and Our Last Chance to Save Humanity.
Last chance? As critical as that? In his lucid concluding summary statement Hansen points to climate system inertia as the reason. Currently inertia is protecting us from the full effects of the changes and can seem like a friend. But, as amplifying feedbacks begin to drive the climate towards tipping points, that same inertia will make it harder to reverse direction. The ocean, ice sheets and frozen methane on continental shelves all resist rapid change, but only for so long. And they are being subjected to human-made forcings far more rapid than any of the natural forcings of the past.
Science is at the core of the book, but Hansen has woven it into a narrative of his encounters with policy makers over the past eight years. In 2001 he was invited to explain current scientific thinking to the cabinet-level Climate Task Force. He focused on changes in climate forcings, in watts per square metre, between 1750 and 2000, using a graph which estimated the effects of a variety changes dominated by human activity. The information seems clear enough as Hansen shares it with us, but it obviously became muddied in the Task Force proceedings, especially when.contrarian Richard Lindzen was invited to the second meeting and focused on uncertainties as well as questioning the motives of ’alarmist’ scientists. Hansen’s belief that the new administration was serious about wanting to understand climate change looks a little naÃ¯ve in retrospect. Incidentally Hansen himself is always aware of uncertainties in his science and careful to accord them proper status.
A further invitation to a different White House group in 2003 saw him centre his presentation this time on paleoclimate and the evidence from the past that large climate changes can occur in response to even small forcings. This topic is explored at some length, with occasional exhortations to readers to hang on if it seems to be getting too complicated. Feedback figures prominently here, as does climate sensitivity to doubled carbon dioxide. The non-carbon dioxide forcings such as methane and black soot attracted some interest at the meeting, but the administration by now seemed to share Richard Lindzen’s perspective and to distrust the scientific community. He records no further invitations to White House meetings.
2003 saw the publication of a paper by Hansen which questioned the IPCC and conventional approach to sea level rise. He explains in the book the evidence from paleoclimate studies of rapid sea level rise and discusses the part played by the huge reservoir of energy provided by the ocean and by ice sheet dynamics. If ice sheets begin to disintegrate we can expect no new stable sea level on any foreseeable timescale. Ocean and ice sheets each have response times of at least centuries.
In 2005 Hansen endured the events described by Mark Bowen’s book Censoring Science: Inside the Political Attack on Dr. James Hansen and the Truth of Global Warming, reviewed here. Some of this ground is traversed again here, and then Hansen offers readers the bad news that the dangerous threshold of greenhouse gases is actually lower than the 450 ppm he had accepted for some years, and goes on to explain how this change of mind occurred.
The name of Bill McKibben enters the scene at this point, for it was in response to his request for an appropriate parts per million figure for his website that Hansen settled with colleagues to re-examine the question. The result was the famous 2008 paper Target Atmospheric CO2: Where Should Humanity Aim? and McKibben’s 350.org movement. The two climate impacts that Hansen believes should be at the top of the list that defines what is ’dangerous’ are sea level rise and species extinction. He explains how reduction of CO2 levels to 350 ppm would restore the planet’s energy balance.
Hansen is widely honoured and respected in the scientific community. He has also taken some pains to make his scientific work accessible to the general reader, as his website reveals. He is happy to accept writer Robert Pool’s description of him as a witness, meaning ’someone who believes he has information so important that he cannot keep silent.’
Criticised for his incursions into the field of policy in more recent years, Hansen is unapologetic about it when he comes to draw conclusions from the research on the appropriate target level of atmospheric carbon dioxide. ’Coal emissions must be phased out as rapidly as possible or global climate disasters will be a dead certainty.’ Should scientists deliver that conclusion and then leave it to the politicians to deal with it? Not in his experience. They will fudge the issue if they can. In particular he is scathing in his rejection of cap-and-trade schemes, which he considers will continue to allow fossil fuels to be burned. He favours instead a rising price on carbon applied at the source, with the fee returned to the population in equal shares. This insistence on the carbon tax method rather than emissions trading may well lack finesse, as his critics allege, but the suspicion of vested interests and of the influence of lobbyists which underlies it is surely justified.
He admits that the phasing out of coal emissions by 2030 is a huge challenge. Energy efficiency measures and renewable energy development will probably not in his view be sufficient to replace coal by then, and he eloquently pleads the case for 3rd and 4th generation nuclear plants.
A scary chapter looks at what he calls the Venus syndrome. Back in 1981 when he wrote his first comprehensive paper on the impact of increasing atmospheric carbon dioxide he presumed that, as the reality of climate change became apparent, government policies would begin to be adapted in a rational way. He didn’t count on two challenges to that presumption. The first is the remarkable success of special interests in preventing the public at large from understanding the situation. The second is politicians’ almost universal preference for greenwash and fake environmentalism. All right, he says, what will happen if we go on burning and push the planet beyond its tipping point? After a careful discussion of consequences he concludes that if we burn all the reserves of oil, gas, and coal there is a substantial chance we will initiate the runaway greenhouse. If we also burn the tar sands and tar shale it’s a dead certainty. Between times lie the storms which will be upon us during the lives of his grandchildren.
Small wonder the scientist has become a climate activist and places such hope as he can muster in the mobilisation of young people to demand appropriate actions from their governments. Activists are not gloom and doom merchants, and it’s clear that he hopes the general public will yet become aware of the real threat discerned by the science and demand the action so far avoided by politicians. All honour to him for the witness he bears.