The solution for land-based emissions is relatively easy: EVs and PHEVs with a clean electricity grid.
The Air and Sea will be more challenging, where the needed range of travel is 1-2 orders of magnitude greater than most cars and trucks.
According to this article from The Guardian. The CO2 output from shipping is twice that of aviation. Currently global shipping fleets are responsible for 4% of total global emissions. This may not seem significant, but the emissions will grow steadily over the next 15 years and the Kyoto accord excludes maritime operations from any emission reducing goals. Most are focusing on airline emissions while ignoring the more severe offender.
With 90% of the world’s goods carried by sea, a carbon tax would likely result in continued increase in the cost of goods (including food exports from the US). We learned from corn ethanol, global inflation of food prices is no bueno. Realizing that lowering global emissions will require the summation of many small reductions, it seems important to consider the global maritime fleet.
What two things do Houston and LA have in common-air quality issues and shipping ports. Which is why The Port of Los Angeles developed AMP, the cargo/cruise ship version of a plug-in hybrid, where ships can turn off their diesel engines and get power from the grid.
This is the basic motivation for my final paper.
So, where can we get a proven clean source of long-range marine transportation with a highly trained work force? I say, ask the US and Russian Navies.