James Hansen recently posted a new letter on climate change called “Tell Barack Obama the Truth — The Whole Truth” [PDF] on his website. In it, he lays out many of his ideas on how to avert climate catastrophe, and I will cherry-pick a few quotes here:

A carbon cap that slows emissions of CO2 does not help, because of the long lifetime of atmospheric CO2. In fact, the cap exacerbates the problem if it allows coal emissions to continue. The only solution is to target a (large) portion of the fossil fuel reserves to be left in the ground or used in a way such that the CO2 can be captured and safely sequestered.

In other words, if I read him correctly, he’s arguing that bringing down coal emissions to anything above zero is not going to work. We’re talking a total ban on coal emissions.

So far so good, in my opinion, but I just want to point out an omission that Hansen makes — he doesn’t tackle the problem of making transportation electric. His take on transportation:

Oil is used primarily in vehicles, where it is impractical to capture CO2 emerging from tailpipes. The large pools of oil remaining in the ground are spread among many countries. The United States, which once had some of the large pools, has already exploited its largest recoverable reserves. Given this fact, it is unrealistic to think that Russia and Middle East countries will decide to leave their oil in the ground.

The problem is this: If we haven’t moved to electric transportation (cars, trains, buses, trucks — forget about planes) by the time the oil runs out, humanity will probably start to use even more sources of CO2, such as shale, tar sands, coal to liquids, and destroy what’s left of the carbon-sequestering soil by producing ethanol.

hansen graph

Hansen presents an interesting graph, shown at right, which indicates that if coal phases out by 2030, land use (forests and agriculture) stops contributing to the problem, and transportation fuels stop contributing to the problem, then we may be able to avert catastrophe. Hansen has discussed reforesting and building up soils to take care of the land use problem, but he has not talked about electric transportation. And that’s my 2-cents worth: electrified transportation is also a critical part of the solution.