Wednesday, February 9, 2011

James Hansen's Climate Future

In his global warming memoir "Storms of my Grandchildren", NASA scientist James Hansen describes his role over the last decade trying to inform policy decisions about climate change. Hansen has been working tirelessly on the science for more than 30 years, and I was most impressed with his reflections on the empirical certainty of climate change, his baseline for any serious attempt to address the problem, and his proposal to reconsider advanced nuclear power as part of the response.

One of the greatest criticisms of climate change theory is its reliance on computer models to make uncertain predictions about the future. According to Dr. Hansen, a better approach is to rely on the empirical evidence from the geological climate record. The layers of ice deposited in Antarctica over the past 425,000 years contain a detailed record of both the relative temperature (from the properties of the ice) and the concentration of heat-trapping gases in the atmosphere (from air bubbles trapped in the ice). This record includes information spanning the last four ice ages, which are caused by natural variations in the orbit and rotation axis of the Earth, and it demonstrates a precise relationship between the average temperature and the concentration of heat-trapping gases. The conclusion is unambiguous: we can expect the globe to warm by 3°C from a doubling of carbon-dioxide.

It may surprise readers of Hansen's book that he is opposed to cap-and-trade legislation as a policy response to climate change. Looking at the results of the relatively modest Kyoto Protocol, he concludes that even legally binding international agreements are simply not effective in practice. Instead, he favors a gradually increasing carbon tax, with the dividends redistributed uniformly to the public to help offset the resulting price increases. According to Hansen, this approach is the only way to ensure that much of the remaining coal and unconventional fossil fuels (such as tar sands and shale oil) stays in the ground and is never burned. His litmus test for any politician who is truly serious about addressing climate change is to call for an immediate moratorium on the construction of new coal-burning power plants that will not capture and store the carbon.

Rather than leave us with a big problem and no way to solve it, Hansen presents a thorough and honest assessment of the potential of nuclear power. If you thought that all nuclear power produces a mountain of radioactive waste that remains dangerous for ten thousand years, then you've never heard of a "liquid-metal fast breeder reactor". The concept for this 4th generation nuclear power (currently operating reactors use 2nd generation technology) has been around since the 1940's, and in 1994 a full scale demonstration reactor was on track to be constructed by Argonne National Laboratory. In that year, the program was canceled by Bill Clinton and Al Gore -- possibly without much thought, as a nod to anti-nuclear activists that helped them get elected. Hansen claims that such reactors are 100 times more efficient than conventional nuclear power plants, and that there is enough of the required nuclear fuel (uranium hexafluoride, a byproduct of nuclear weapons production) in U.S. stockpiles to power the country for the next thousand years. The only waste products can be stored safely on-site for just a few hundred years.

Hansen believes that we have not yet reached a tipping point, and that we have the power to save the future for our grandchildren if we choose to do so. He understandably remains skeptical that we will actually make that choice, and this book is his final attempt to make his message heard. If we don't listen, we have nobody to blame but ourselves.