and other public transport. Could we have a category to account for their use, as this forms the majority of our (well, DPs lol) travel?

LPG

Public transport is a tricky one, but is probably something I’ll look at in the future. The transport direct website calculates carbon costs for pretty much any journey inside the UK, so it must be possible!

James
It definitely is tricky and I wish you luck when you tackle it. The figures quoted on the calculators I’ve looked at don’t look credible to me. Clearly the emission per person depends on how full the bus or train is, but how should you take account of this? On the face of, a passenger in an empty bus has a much higher emission than in a full bus, but why should he or she be penalised? It’s not his or her fault the bus is empty! I’d suggest two possible approaches. 1. Just have one figure for bus and one for train based on the average occupancy in the UK. 2. Say the provision of public transport is the responsibility of government and they are responsible for the associated emissions. The emissions of individual passengers can then be ignored. This is consistent with the proposed TEQ system advocated by David Fleming (and now by CAT) and would be my choice – makes life a lot easier for you too.
All that is for trains and buses. I definitely think that leisure air travel shoild be in the calculator, but there is no single figure per passenger mile for planes and so I think the user just has to get a figure from a specialist calculator

Disregarding the contribution from public transport isn’t entirely fair as it implies that public transport makes no contribution to pollution whereas obviously it does. The fact that the service has been provided by a third party does not alter its impact on the planet.

If you could ignore the contribution from public transport then why should you ignore the carbon footprint of buses and trains which are provided by private companies selling a service to the public but not ignore that from air travel? You could of course argue that air travel is voluntary and so should be counted but then should you ignore any contribution from driving for work related purposes or commuting? Or if one ignores public transport then is a trip to Prague by train to be treated as zero cost while the same trip by car or air travel is not?

This is an argument that affects all emission quota systems, as well as carbon calculators like mine. In an emission trading system, you’re right, ALL public transport would be counted against the quota of the company running it. They would pass the price of that quota on to the user financially, rather than with carbon credits or whatever. That includes buses, trains, and air travel. The only things to come out of an individual carbon quota would be domestic emissions.

I think with the carbon diet, it’s air travel that we’re making an early exception for, rather than bus or train travel. The simple fact is that air travel is the single most damaging thing you can do in terms of your carbon footprint, so it has to be included to give people a realistic idea of their footprint. Hopefully we’ll be able to expand the system to include public transport as well, but it’s certainly a lower priority for me at the moment.

If I drive to work, I use a certain amount of carbon. If I get the bus or train, I use less, but still some. A point to consider though is that the bus or train was going anyway, so I’ve saved 100% of the carbon from my car journey by using the bus. I know it’s not exactly scientifically rigorous, but that’s my justification for treating public transport as a lower priority at the moment.

I agree with all of James’ latest posting.

Well air travel probably isn’t the most single damaging thing that people do simply because air travel is, for most people, a relatively infrequent occurence. Compared to what it achieves air travel is phenomenally damaging but for most people cars or simply heating their house will probably do more damage over the course of a year than an annual flight to Spain. Yes you could ignore any contribution from a train or bus on the basis that “it was going anyway” but the same could be said of air travel.

Acccounting for public transport is a lower priority than accounting for emissions from cars. But that is partly because assesing the impact of public transport is harder because it can not be directly attributed to one individual. If I drive to Edinburgh I can easily account for the CO2 from the 40 or so litres it might burn. If I take the train there is an increase but only indirectly because my action is part of society’s overall action that lead to the train running and so having a footprint. Accounting for that shared responsibility is a very grey area but it is not costless.

Sorry to keep this going. I agree with your second paragraph. Because it is so difficult to assign bus and trains to passengers because the occupancy varies so wildly, it makes more sense for the operator to have the carbon ration. The emissions are not being ignored, just not being assigned to an individual for practical reasons.

A return flight from Newcastle to Malaga emits around 0.45 t CO2, 1.35 t CO2 equivalent assuming a factor of 3. My CO2 emissions from gas for home heating and hot water are 0.85 t at 3 Sept, so my full year will be less than going to Spain (not that I did by the way!). In addition to the big impact of a holiday flight, it’s an activity that anyone can do without, unlike heating your home. So for most people the biggest single thing they can do to reduce their emissions, by far, is to pack in holiday flights. Assuming a standard occupancy for holiday flights is probably not unreasonable and so the emissions can be calculated with adequate accuracy.

“Assuming a standard occupancy for holiday flights is probably not unreasonable and so the emissions can be calculated with adequate accuracy”

Then why not assume a standard occupancy for public transport?

How did you get a figure of 0.85 Tonnes for home heating. Typical figures for electricity production are 1Kg CO2 / KWh and a typical domestic consumption is about 4500 KWh pa. I don’t have the figures for gas to hand but they are broadly similar. So your house will typically account for up to 10 tonnes of CO2 pa even before you go anywhere. Similarly if you drive perhaps 10000 miles a year, again a typical figure, then your car will produce about 2 – 2.5 tonnes CO2 pa. It doesn’t mean that tackling flights is wrong because they are often optional and so could be reduced but it is only a small part of the problem.

My answer to your first question is that I believe the occupancy of buses and trains varies much more than the occupancy of holiday flights.
I think your factors are wrong. Before I discovered carbon diet I have been using the following ClimateCare factors: gas 0.19 kg per kWh, electricity 0.43 kg/kWh. Carbon diet uses the latest Defra figures which are similar. I am not a typical car user. My car miles to date in 2007 is 2000, average 60 mpg (measured over several months), so 33 galls diesel. I use a factor of 12.2 kg/gallon diesel.