While eating vegetarian Pho the other day, I had an idea relevant to our running series of discussions on air travel. Specifically, this: if we are basically certain to consume all the world’s accessible oil eventually and, if the long atmospheric life of carbon dioxide means that it matters little whether emissions occur in one year or another, might it not be sensible to fly about without guilt. After all, the atmosphere is doomed to absorb all the CO2 from oil anyhow. You could compare it to keeping warm beside a fire you didn’t start, and which is naturally going to carry on burning until there is no fuel left.
For a brief moment, this seemed like a good justification. Unfortunately, it suffers from at least two critical problems.
Firstly, it inappropriately downplays the importance of timing. This is true both environmentally and economically. Environmentally, we might compare CO2 emissions from oil to drinking vodka at a party. You have the option of taking one shot an hour, until the bottle is gone, or guzzling it all in a few minutes. In theory, both approaches produce a similar amount of intoxication. In one case, it is just bunched up at the beginning. The trouble lies with non-linear responses to such external forcings. Your liver and kidneys can probably handle one shot an hour. They may well be unable to handle twenty shots an hour. They might fail, and you might die. Something similar could be true of the climate system. It might be possible to avoid catastrophic tipping points if emissions rise and then fall back in a long smooth arc. It’s not an ideal option (global emissions should already be falling, if we really want to avoid catastrophe), but it is a safer option than guzzling.
Economically, it also makes sense to portion out our remaining fuel. Essentially, that is because we need to make a transition to a low-oil, low-carbon global economy. In the future, oil will be used in fewer ways and will be used more efficiently in all of them. To take an example, it would seem like folly to burn gasoline to travel 10km to work. Because oil will be both more costly and more efficiently used in the future, it is essentially worth more there and should be saved. There are also areas in which ready replacements for oil do not exist: air travel being a critical one. Saving our oil for the future cases where nothing else will do makes sense.
Worse stuff than petroleum
Secondly, there is the enormous problem of fuel substitution. Kerosene made from petroleum is a high-emission option, but nowhere near the worst option out there. Fuels made from oil sands or (shudder) shale oil could be much more emissions intensive. The same is true of palm oil – a biofuel largely grown in areas of former rainforest. Finally, there is the danger that the coal-to-liquids technology used in oil-starved WWII Germany and Japan could become widespread. Eventually, it is likely that at least some commercial jet fuel (and perhaps more military jet fuel) will come from such horrid sources. That is a big problem.
While there is some chance we can burn all the world’s oil without wrecking the climate, that is enormously less likely if we are going to burn all the coal as well. Avoiding the switch to suicide fuels is a critical task, and one that can be aided by limiting air travel.