I recently waved off my brother at Suvarnabhumi Airport on his way home to the UK.  If this were a sensible world, run by rational people, then that should the last time for a long time. 

But of course the world is not sensible and those running it are far from rational.

To save the planet from frying, we have to de-carbonize the economy.  Now there are all sorts of challenges on the economic side of this, but let’s just focus today on the technical aspects.  How can we stop burning fossil fuels and agrofuels in doing what we want to do?  Always on the understanding that it turns out to be impossible to do X without creating large-scale emissions, then we’ll have to give up X.

The cheapest and possibly easiest way is to be more efficient.  Before we change what we do, we can make things better by being more efficient in what we are already doing.  Better insulation; more efficient motors in everything from the compressor in your fridge to the jet on an aircraft; turning things off when not needed (including not leaving them on standby).

That’s all very good and commendable but it won’t nearly be enough.  So the next thing, which also wouldn’t require any great technological shift, is to change how we do things.  Increase the use of public transportation; source supplies (including your food) locally; teleconferences rather than face-to-face meetings; go vegetarian.

Again, good, but it won’t save the planet.

The big one will be switching to other sources of energy, which do not involve increasing the amount of greenhouse gases.  Replace coal-, oil- and gas-fired power stations with energy from wind, wave and sun.  Technically, this could supply the bulk of the energy used in fixed establishments – homes, factories, offices, shopping malls.

In a stored form, such as electric batteries or hydrogen produced from electrolysis powered by ‘clean’ sources, this can also be used to power cars.  And electricity has of course long been available as a source of energy for trains and trams.

But there aren’t batteries small enough and light enough and efficient enough to think of using them as a way of powering planes. 

Nor is hydrogen much of a prospect.  With about a quarter of the energy value by volume of jet fuel, planes would start to resemble space rockets where the vast bulk of what goes up would be the fuel needed to do it.  And the advantage of burning hydrogen to run cars – that its waste product is harmless water – is in fact a danger at high altitudes, where water vapour acts as a greenhouse gas.

In other words, aviation is perhaps the most difficult technical problem that faces us in the need to de-carbonize transportation systems.

One might then think that this is where greatest efforts would be made to reach a common understanding that of all the things we now do, flying by planes is the one most likely to end up on the scrap heap of globally-polluting activities, and it was time to crank down the system.

And one would of course be wrong. 

Aviation fuel, almost unique among other fossil fuels, is untaxed.  Subsidies for air travel abound, these days largely in the form of government pay-offs to support building more airports and more runways at existing airports.  And the UK government is currently pushing through parliament a Climate Change Bill that will give legal teeth to the drive to reduce climate-changing emissions.  Except that it specifically excludes aviation.

(There is similar concern about the contribution of shipping to climate change.  Its negative impact appears to have been seriously underestimated and it too has been left out of the UK’s targets for reducing emissions.)

The media is awash with advertisements supporting international tourism and, by implication, the flying that this normally entails.  A recent TV programme gushed over the growth of the domestic market for air travel in India and the excellent employment opportunities it created for young middle-class women who crave the glamour of using gobs of make-up to serve tea.  I even came across an interesting article that traced the refusal of House Republicans to support their own President’s financial bail-out package to the fact that these days none of them maintain homes in Washington and rely on cheap air travel to spend maximum time in their home constituencies. 

But it all must change. 

Either the amount of flying going on must be severely curtailed, or we have to come up with an alternative, environmentally-friendly way of moving across continents.

My brother complained that his trip home involved a lengthy lay-over in Doha, making it close to a 24-hour journey.  Maybe next time he’ll enjoy a more leisurely 3 days or so in the spacious comfort of an airship.