Given that air travel is the fastest growing cause of global warming, participants at environmental conferences can't escape the irony of jetting thousands of kilometres to get to the venue.
But there are ways to partly absolve such sins.
Delegates flying to Durban for the recent COP17 climate change conference could offset their emissions by buying virtual trees at King Shaka International Airport. Each virtual tree (cost = R90) translates into a real one planted by Food and Trees for Africa, and offsets four hours flying time.
You too can easily calculate and offset your jet fuel emissions this way by using the My Tree in Africa carbon calculator. But follow these steps or it won't work!
1. Enter the flight duration in hours (for a single flight)
2. Enter the number of flights
3. Click "Add Flight"
4. Click "Calculate"
5. The next page to open will show you your flight's carbon output and the number of trees needed to neutralise it.
A cautionary note on offsetting: it helps the climate change crisis, sure, but it's certainly no perfect solution and is rife with complexity and controversy. The first action to take for the environment should always be to reduce your emissions and THEN look at ways to offset what you absolutely haven't been able to reduce. For more on this thorny topic, see Is planting trees stupid?
You can also plant a tree yourself of course, but keep in mind that some species - especially those indigenous to an area - are rather better at keeping carbon out of the atmosphere than others.
(Olivia Rose-Innes, EnviroHealth Editor, Health24, updated January 2012)