forum
type all threads links
  rss feed

Our CO2 from flying - in case you were wondering (cragcentral message#85)
Thread started on 16/12/2006 16:47

andy_ross

andy_ross

air transport

In case you were wondering why CRAGs are being much harder on flying than the government carbon bean counters, here is the key quote from the 1999 IPCC SPECIAL REPORT: AVIATION AND THE GLOBAL ATMOSPHERE

http://www.ipcc.ch/pub/av(E).pdf

“Over the period from 1992 to 2050, the overall radiative
forcing by aircraft (excluding that from changes in cirrus
clouds) for all scenarios in this report is a factor of 2 to 4 larger than the forcing by aircraft carbon dioxide alone. The overall radiative forcing for the sum of all human activities is estimated to be at most a factor of 1.5 larger than that of carbon dioxide alone.”

Whereas Colin Challen’s 25/5 Challenge suggests using
0.15kgCO2 per km for short-haul, and 0.11kgCO2 per km for long-haul flights, I think most if not all of the CRAG groups are going for something more like what is quoted at
http://www.coinet.org.uk/solutions/carbon-rationing i.e.
0.51kgCO2 per km within Europe, and 0.32kgCO2 per km beyond Europe.

For the full story on aviation emissions check out

http://www.chooseclimate.org/flying/index.html

andy

‹ Company to offer 'green gas' by investing in methane-generated gas production So just how much carbon have we got left? ›
» login to post comments

aviation numbers are too high

written on 23/12/2006 20:50

john ackers

john ackers

I think the CRAGs ought to review the aviation numbers they are using.

There is a lot of variation between the different models, you can get a 50% change in CO2 when you switch between models e.g climate care to choose climate to CRAG.

I have looked at two algorithms: Choose Climate algorithm and the Climate Care algorithm algorithm in detail. The differences are:

  1. Takeoff fuel must be separately itemised as a fixed amount of fuel. Both algorithms use similar numbers for fuel take off and landing (based on this report). The CRAG spreadsheets that that have the 0.51 Kg/Km and 0.82 Kg/mile metrics don’t separately itemise takeoff fuel ; short flights are underestimated and long haul flights are wildly overestimated.
  2. RFI. choose climate use a radiation forcing index (effect of other gasses apart from co2) of 2.7. ECI say that 2.0 is OK in a document written by ECI but commissioned by climate care. This is the controversial aspect of the calculation.
  3. Larger planes are preferred (if not required) for long haul journeys. Smaller planes appear to use less cruising fuel per passenger per Km. Climate Care assume that passengers travel on B737 400 for distances under 3500 Km and B747 or A340 for everything else. The Choose Climate model is weak in that all flights are assumed to be by 747 which uses a lot of fuel per person at takeoff. (I have emailed website author but not had a response. But he would probably say just plug in the other aircraft).
  4. the number of seats on the plane seems to vary between operator. Climate care assume that a B737-400 has 180 seats which according to the the 737 Wiki is about right as it seems to vary from 170 to 190 depending on the variant. According to the 747 Wiki A typical three-class layout accommodates 416 passengers, while a two-class layout accommodates a maximum of 524 passengers. Choose climate use 380. Climate care assume 400 but that is, I think, the average of a 747 and an Airbus A340.
  5. Occupancy. Climate care and choose climate 80% and 100% respectively for seat occupancy. I think the likes of EasyJet and RyanAir do achieve 80% and above.
  1. Freight. Climate care assume that 10% of fuel is used to carry freight.

I think we need to agree on what numbers we should be using and use those numbers in our calculations, both in spreadsheets and online. Ideally, we should use different formulas for different models of plane.

Also, Chit Chong (partner of Lucy in Islington CRAG) also emailed me with similar issues which I’ll leave him to post.

John

p.s. The Islington group in Jan 07 meeting decided to use Climate Care model but that was largely based on my comments.

Re-edited to improve clarity on 13-Apr-07.

 
» login to post comments

Radiation Forcing Index and Aviation Metrics

written on 12/2/2007 23:51

david

david

The original source for aviation forcings was the IPCC’s Aviation and the Global Atmosphere (1999) http://www.grida.no/climate/ipcc/aviation/071.htm#623 (accessed 12/2/2006)”>1. The relevant section is 6.2.3. Alternative Indexing of Aviation’s Climate Impact-RF Index which says:

RFI is a measure of the importance of aircraft-induced climate change other than that from the release of fossil carbon alone. RFI ranges between 2.2 and 3.4 for the various E- and F-type scenarios for subsonic aviation and technical options considered here

Jardine (2005) http://www.climatecare.org/_media/documents/pdf/Aviation_Emissions_&_Off… (accessed 12/2/2006)”>2 (the ECI report commissioned by Climate Care) suggests 1.9 as the better figure, based on the TRADEOFF project . On page 7:

The IPCC calculate the change in radiative forcing of aviation emissions since pre-aviation times to be 0.049 W/m2 (See Figure 5).. This corresponds to a radiative forcing index of 2.7 as the total radiative forcing of 2.7 times that of CO2 alone (0.018 W/m2). However, a recent study (TRADEOFF) has updated this figure and a value of 1.9 is now the best-quantified estimate of radiative forcing index of aviation emissions.

Sausen et al. (2005) http://folk.uio.no/gunnarmy/paper/sausen_mz05.pdf “>3 compare the IPCC (1999) and TRADEOFF results in more detail, and their Fig. 1 gives a good breakdown of the components of the aviation forcing and the level of uncertainty and understanding. The estimates for O3, CH4 and (especially) contrail forcings have fallen, meaning the total radiative forcing (0.048 W/m2) is 1.9 times that of the CO2-only forcing (0.025 W/m2), rather than 2.9 according to the IPCC (1999). Cirrus cloud forcing is highly uncertain and not included in these totals. Its likely range is 0.01 to 0.08 W/m2.

Although these effects do undoubtedly scale up the climatic effects of aviation emissions, Forster et al. (2006) 4 note that using the RFI method to quantify it for emissions trading is rather suspect. Normally, you’d use Global Warming Potentials which define the effect of a unit greenhouse gas over a defined timescale. Instead, the RFI measures the cumulative globally-averaged forcing by aviation emissions up to a certain year. It doesn’t define the timescale of the climatic effect, which is important where non-CO2 forcings operate over variable timescales. And to be fair, we should also include non-CO2 forcings of other sectors, like heating or electricity.

Unfortunately GWPs are unsuitable for most aviation forcings too (Forster, 2006; IPCC, 1999; Jardine, 2005). So it’s very much a case of “watch this space” for a reliable metric to scale up aviation emissions. Until then, we have to fudge it.

There’s a good overview of this area in the Workshop on the Impacts of Aviation on Climate Change: A Report of Findings and Recommendations (Section 2.3.2, p.25)

  1. IPCC (1999) Aviation and the Global Atmosphere: 6.2.3. Alternative Indexing of Aviation’s Climate Impact-RF Index [online]. Available from: http://www.grida.no/climate/ipcc/aviation/071.htm#623 (accessed 12/2/2006)

  2. Jardine C. N. (2005) Calculating the Environmental Impact of Aviation Emissions [online]. Available from: http://www.climatecare.org/_media/documents/pdf/Aviation_Emissions_&_Off… (accessed 12/2/2006)

  3. Sausen, R. et al. (2005) Aviation radiative forcing in 2000: An update on IPCC (1999) Meteorologische Zeitschrift 14: 555-561 – available from: http://folk.uio.no/gunnarmy/paper/sausen_mz05.pdf

  4. Forster et al. (2006) It is premature to include non-CO2 effects of aviation in emission trading schemes. Atmospheric Environment 40:1117-1121

 
» login to post comments

Other radiative forcing?

written on 17/5/2007 14:05

Jamie

Jamie

Has anyone seen the calculator at www.atmosfair.de? It seems to offer the most comprhensive number of variables (i.e. airports, aircraft type and different methods for distances beyond simple long vs short-haul) but gives a figure almost three times that of Climate Care. With Climate Care’s methodology rubber-stamped by ECI and Atmosfair’s by the German government, it’s hard to know which is more accurate.

There are some obvious points in Atmosfair’s supporting documentation about radiative forcing that cites the 1999 IPCC report which are probably out of date, and it seems to allude to ‘other greenhouse gases’ enough to suggest potential over-compensation but apart from that I cannot see why there are such wildly differing figures. I’m not a scientist so any help to bring clarity would be greatly appreciated.

 
» login to post comments

Aviation Forcings

written on 7/7/2007 13:28

Amy Lunt

Is there any up to date info yet on the effects of aviation and radiative forcings?
Are CRAGs still sticking to the original conversion factors or have some chosen to use other calculations?

 
» login to post comments

the latest from HMG

written on 7/7/2007 19:16

andy_ross

andy_ross

This is what our dear government tells us on their new carbon calculator website:

“The full climate impact of aviation goes beyond the effects of CO2 emissions. Apart from emitting CO2, aircraft contribute to climate change through the emission of nitrogen oxides (NOx). This forms the greenhouse gas ozone, especially so when emitted at cruise altitudes.  Aircraft also trigger the formation of condensation trails, or contrails, and are suspected of enhancing the formation of cirrus clouds, both of which add to the overall global climate changewarming effect. These extra impacts are examples of effects which are collectively known as ‘radiative forcing’.

“There is still considerable scientific uncertainty about the scale of the impact of these radiative forcing effects.  However, the climate impact of aviation emissions, including radiative forcing, has been estimated by the Intergovernmental Panel on Climate Change (IPCC) to be 2-4 times that of the CO2 emissions alone.  Currently, government uses a factor of 2 when offsetting its business flight travel.”

http://actonco2.direct.gov.uk/index.html

 
» login to post comments

Don't take my wings away

written on 25/3/2007 11:49

john ackers

john ackers

"Don't take my freedom away, Don't take my holidays..When it's cheaper to fly than to park at the airport..."

Have a listen to this gorgeous song [you tube] by Shannon from Seize the Day. The lyrics could have been written for CRAGgers. They played it at the Green Party Conference on Friday night in Swansea.

Before they played it they asked people to pledge to never travel by air again. Two people did. Of course the audience thought that was a very noble gesture. But I suspect that they were members of a CRAG and the prospect of not having to ever calculate aviation emissions again was too great an opportunity to miss.

 
» login to post comments

Act on CO2 air travel calculations

written on 29/1/2009 11:18

john ackers

john ackers

Taking up startcapstick's comment about the carbon costs of flights, according to the ActOnCO2 Methodology "non-CO2 effects such as from Radiative Forcing from NOx and water vapour emissions are not factored into the calculation on the advice of DEFRA’s aviation consultantProfessor David Lee, Director, Centre for Air Transport and the Environment (CATE), Manchester Metropolitan University and others. This is because of the uncertainty and ongoing scientific research and debate around the scale of these wider impacts."

So much for the precautionary principle.

 
» login to post comments

I am not sure if this has

written on 29/1/2009 13:37

andy_ross

andy_ross

I am not sure if this has changed but when I last checked (see my post above) the government was using a factor of 2 when offsetting its own business flight travel. This is the low end of the IPCC range of estimates i.e. minimum precaution (see paper referenced at top of the thread). Not surprisingly this minimum is not applied to calculating the public’s flight emissions at the government website ActonCO2!

 
» login to post comments

Taking model of plane into account

written on 10/3/2009 11:10

john ackers

john ackers

This Feb 2009 report from ECI describes more accurate calculations based on information about the particular plane on a route using data from Sabre, the ticket booking operator. There is also a useful comparison of existing calculators including Defra’s and Climate Care’s. The difficult issue of determining the radiative forcing multiplier is not tackled (discussed above).

By way of a comparison, Virgin claim that they use real fuel consumption in their calculator which I would have thought would be just as accurate. But Virgin like Defra use an radiative forcing multiplier of 1.

 
» login to post comments

action by business air travellers?

written on 22/11/2009 18:54

clairemilne

Views, please, on how people who (like me) find themselves having to fly for their work can best behave.

Refusing to fly doesn’t look like an answer – that most likely means your place or even your job will be taken by someone else with fewer qualms; while as insiders, reluctant flyers can press to minimise air travel, using teleconferencing, sensible project planning, and persuading colleagues that some trips are unnecessary.

But if you end up having to fly…

- is it a good idea to get your sponsor to pay for carbon offsetting, and if so, what form should this take?

- can we put membership of frequent flyer schemes to constructive use, eg getting points automatically credited to an environmental cause? The point of this would be to raise awareness of how iniquitous these schemes are in the first place – they basically encourage people who already fly too much to fly even more. Again one can simply opt out, but my question is, can one do something useful from within?

Is any group or website providing advice on issues like this? There’s plenty about not flying for leisure or personal reasons, and WWF has a “one in five” challenge for reducing business air travel, directed at large companies. So far I’ve found nothing directed to the individual business traveller.

 
» login to post comments

Reducing impact of flying

written on 23/11/2009 09:24

jamesinyork

Hi guys

Its been a lonnnng time since I’ve posted here!

I am going to stick my neck out, and suggest that the technical issues about the total emissions of a plane on particular flight (which I’ve only scan-read) are of only limited use in quantifying the CO2 ‘impact’ of an individual taking a flight.

Basically, the idea seems to exist that you simply divide total flight emissions by the number of seats/passengers. In my view this is quite wrong.

These days, flight tickets are sold at various prices, so not all seats are equal. Basically the more you pay for the ticket, the greater the CO2 you are ‘responsible’ for, and the cheaper the ticket, the less CO2. This is because the amount of money the airline receives will determine their decisions about running (or not running) future flights, which is mainly what counts in the end (number of planes flying, not the no of passengers on them). (this is a simplified version of the theory)

So, to reduce your impact, make sure you buy as cheap a ticket as possible. (IMO any ‘offsetting’ is irrelevant to the equation, linking it with the flight is a greenwash trick). If everyone bought only cheap tickets, the airlines would go out of business and no flights would run. Similarly, just a few expensive business tickets will sustain planes running largely empty.

I’m afraid to say Claire that to a large extent, its the business travellers who keep the flights in the air (esp those going business or first class) and therefore business is ‘responsible’ for a very large proportion of airline emissions (IMO).

I suspect there might be a some differing views on this so feel free to comment!

Cheers
James
(now in Cambridge)

 
» login to post comments

Make sure your company does carbon accounting

written on 23/11/2009 14:53

Jamie

Jamie

Hi Claire,

It’s an interesting question, and my response would be to make sure that the company you work for is undertaking carbon accounting in line with an accepted protocol such as the Greenhouse Gas Protocol from the World Resources Institute:

http://www.ghgprotocol.org/

There is lots of web-based software now emerging that will help in making this process much easier. The company I work for (AMEE) has just partnered with a major accounting company – SAS – so that carbon accounting can be increasingly integrated with financial accounting.

Carbon is a huge liability on any balance sheet because of the fact that climate change will cause massive economic damage when it hits. So if your company is behaving rationally from an economic perspective then it will know what its carbon footprint is, and be working to reduce it significantly and quickly. Reducing flights and replacing with video-conferencing is an easy way to make huge reductions.

Most executives who understand climate change (and this is now a very high number) are beginning to understand that offsetting doesn’t really cancel emissions, and so I would avoid going down that route if I were you. Similarly, frequent flyer miles being used in the way you suggest would offer a peverse incentive to fly more in order to save more of the environment. Which is obviously a paradox.

So I would strongly recommend explaining the economic implications of not reducing carbon, if necessary referencing the Stern Review: http://en.wikipedia.org/wiki/Stern_Review.

If you then end up going on some business flights that are part of a well-understood and articulated carbon budget that offers reductions over a set timeframe, then I would not feel bad about taking them.

Obviously for any short-haul flights, I would highly recommend taking the train. I usually get lots of productive work done on a long train journey. I find it cultivates a great mindset for getting stuck into something.

Jamie

 
» login to post comments