I tried a few sites for calculating carbon footprint.
Go Neutral is an Australian site so it probably I would expect it to be pretty apt. It uses households rather than individuals. The result: 14MT (metric tonnes) or 13014 kilos. They give a nice comment that we would need 21 trees: with a household of three adults, I need to plant 7 trees to be personally carbon neutral.
Nature Conservancy is a US centric site, so it expects me to live in a US State: I picked California due to the climate. This time the household estimate is 17 tons of CO2 (15.4 metric tonnes). The site gives me the information that this is half the US average and twice the world average.
Carbon Footprint was much more detailed, and allowed Australian data. Some of the instructions were a little confusing. This sit also included secondary footprint. According to this site, we produce 3.2 (metric) tonnes
with the Australian average being 16.30 tonnes, the average industrial being 11 tonnes, the world average at 4 tonnes. The site says the worldwide target to combat climate change is 2 tonnes. This seems quite a lot less than the others.
Al Gore's site Take Action there is a very simple calculator, for Americans. I decided it would be better to just try personal information: it was 5.5 tons (5 tonnes).
Going over to Yahoo Green, and it says I cause 9.4 tons per year, exactly the US average of 9.4 tons. This is quite different from the results at other sites, and only seems to look at travel. 8.4 tons come from a return international trip every year.
I tried the UK government Act On site: it was very thorough but asked lots of UK questions: it expected that I would have some kind of built-in house heating for example. This Winter was quite cold for Sydney: I think we needed to turn heating on twice. I avoided the Flash version (why do they have these things? they take so long to load) but the HTML version estimated that I had no CO2 footprint for our home and appliances, which doesn't seem right. For the transport, it estimate 2.39 tonnes, and suggested a target of 1.91 tonnes. It turns out this is just a 20% "aspirational" target.
So it seems my carbon footprint is probably between 3 and 6 tonnes, and this is maybe 1/3 of Australian average and maybe 1/4 of the US average. I suppose because I walk to work and the local shops. Actually, I don't think I have any close friends who even have cars, now that I think about it.
But what is noticeable is that my typical one international flight per year contributes such a lot of carbon: maybe 2 tonnes. Australia is a long way from everywhere, indeed, but it makes me think that I should avoid flights outside our hemisphere: basically, Asia would in and everywhere else would be out. Or is that I should pack light and diet before a long flight? A friend who was an aircraft dispatcher said that planes use a lot of fuel merely taxiing: do I need to avoid airports with lots of waiting and taxiing? (Has Heathrow improved in this?) If planes use most fuel taking off, then is it better to avoid full flights which might require more engine grunt on takeoff and therefore fuel?
If any readers have any pointers to sites wit ideas on how, if you have to fly, to fly as green (i.e. as responsibly) as possible, I'd like to read them.