That humans are raising Earth’s temperature is about as certain as any scientific consensus can be. And while the western world may be able to mitigate the impact somewhat, a low-lying Pacific island state can hardly build a sea wall around their entire country. Therefore, I feel it’s very important that people consider the amount of carbon dioxide their activities are generating and do something about it.
So I’m pleased to say that the Mozilla Foundation (that is, Frank, Zak and I) hope to use a small part of our giving budget to offset all the emissions caused by all flights taken by us or Foundation-sponsored volunteers (e.g. localisers attending FOSDEM last February) in 2006.
The current plan is to do this by making a donation to a carbon offsetting charity. The charity concerned needs to be a formal charity, and ideally would be US-based for convenience. So far I have only found carbonfund.org which meets those criteria; if anyone knows of others, I’d be interested to hear about them.
In doing the research to try and work out how much we need to donate, I have been looking at the different carbon offsetting sites to see how they calculate their figures.
The first thing is that the flight distance between two points on the earth seems to be fairly standard – everyone uses Great Circle distances (handy calculator). A great circle is the shortest distance across the surface between two points on a sphere.
However, what does vary is the figure used for emissions per mile, and then the cost per metric tonne of CO2 emitted. This can lead to wildly different offsetting figures for the same flight. I’ve tried to reverse-engineer what these sites do using inputs for flights of different lengths.
|Site||$ per Kg||Kg per mile||$ per mile|
: Or, seemingly, 0.4 for flights under 3-4000 miles)
So it seems that if you offset with atmosfair.de, you pay almost ten times as much as with carbonfund.org! Of course, you would expect the amounts to be somewhat different, if they were tied to the real cost of whatever initiatives were being taken, and because working out the actual impact of 1Kg of carbon is an inexact science. But still, a tenfold difference seems excessive.
Again, if you know of other sites which provide carbon emission calculators for flights, and enough information to be able to work out the above figures for comparison, let me know and I’ll add them to the table.