Tag Archives: co2

Aviation, conservation, environment, technology

General Aviation – Mostly Harmless?

Leave a comment

I wasn’t very environmentally friendly over the Christmas holidays.

A CO2 emission of 2.1 tonnes, my share of a return flight to the US, represented about a quarter of the average UK person’s total yearly emission of 9 tonnes.

c152
Mostly harmless?

I used this fact recently as a topical lead-in for another article, adding that I once flew light aircraft as a hobby (=double criminal for sure).   But that presumption stuck in my head and prompted some research into the impact those little private planes really have in the big picture of global warming.

‘General Aviation’ is the name used in its broadest sense to include all non-scheduled corporate aviation plus private and sport aviation.   Take out the corporate jets, and we’re left with the ‘Piston GA’ category of the sort covered by my license, and including familiar planes like the four seat Cessna 172.

USA emissions data fell most readily out of Google, with the Aircraft Owners and Pilots Association (AOPA) pointing to EPA data showing GA’s contribution of less than 1% of all US GHG emissions from the transport sector, and Piston GA only 0.13%.   They argue that this is small potatoes compared to other sources more worthy of the regulator’s attention (see table) .

Table from the AOAG showing 2005 EPA data
Table from the AOPA showing 2005 EPA data

So that’s 2.4 million tonnes of CO2 from relatively small piston engined aircraft (a Tg or tera gram is one million metric tons, or tonnes) .   FAA data on the number of private licenses suggests this emission is associated with 200,000, of the 600,000 or so total pilots in the US.

In the UK, there are far fewer private pilots overall (around 35,000 license holders), and Piston GA in particular has a much smaller role in the economy.

We can estimate C02 from an assumed fuel consumption for the Cessna 172 of 8.6 US gallons per hour, producing 2.3kg CO2 per litre, equating to 75kg CO2 per hour.  Estimating the average recreational pilot is flying less than 50 hours a year equates to 3.7 tonnes CO2, which for 35,000 licensed UK pilots is 130,000 tonnes CO2.

Having a low relative impact is not an excuse to do nothing in this case.  Two efforts to reduce emissions further are exemplified by the Carbon Neutral Plane Programme, which arranges for aircraft owners to offset their aircraft’s emission through financial support of CO2 reduction projects, and technology incentives like the Green Prize competition run by CAFE and reported here.  Technical innovations include engine modifications within existing airframes, such as the introduction of Full Authority Digitial Engine Control (FADEC) – for 15% fuel savings, the substitution of a single, high-efficiency jet in place of  two piston engines, and more radical solutions such as electric powered aircraft.

In summary:

  • The average guy you see out for a fly on a Sunday afternoon is putting 3.7 tonnes of CO2 into the atmosphere over the year
  • If you take one  long haul holiday with your partner, your combined associated emission is larger, at say 4 tonnes CO2,  than the private pilot’s (double that if you take a couple of kids)
  • There are around 35,000 private pilots in the UK
  • There are over 60 million people in the UK – many taking foreign holidays

I guess we all need to decide which of our carbon burning activities are the more unnecessary and decadent – it’s not obvious.  And while I sense some unreasoned prejudice against it, my point is not to defend GA or any other position, but to illustrate the importance of understanding in general on CO2 issues: (a) impact per unit activity, (b) absolute impact, and (c) the opportunity cost of not putting your time, financial, intellectual, management, and emotional  resource where it can do the most good.


conservation, environment

For Peat’s Sake…..

Leave a comment

(This article was originally published at conservationtoday.org)

We can all take action to help combat global warming.  Here is something for the gardeners amongst you to think about.

Direct man-made CO2 emissions are problematic enough, but they are only part of a complex interplay of sources and sinks for greenhouse gases that is still beyond our full understanding. For example, there has for some time now been concern over frozen peat bogs thawing and releasing stored up methane, locked away for millenia, and far worse than CO2 as a greenhouse gas.

Leave it in the ground

But peat is our friend too; and you can help by leaving it where it is.

Why? Because peat is largely made up of dead plants, rich in captured carbon that has been prevented, due to the moist air-free bog environment, from fully decomposing back to CO2. Drain the bogs, distrurb or harvest the peat, and the carbon recombines with oxygen in the air, taking us back to square one.

The National Trust are at the forefront of public consciousness raising about peat in the UK, illustrating the issue with numbers that are far from intuitive. For example, the Trust estimates there are 100kg of carbon locked in every cubic metre of peat; which in CO2 terms is like driving a car for 2000 miles. In their report, Natures’s Capital, we learn peatlands are the UK’s single largest carbon reserve, amounting to around 3 billion tonnes, or equivalent to 20 years’ worth of man-made CO2 emissions. Across the globe, although peat covers only 3 per cent of the global land surface, the amount of carbon stored within it is enormous – equivalent to twice that of all the world’s forests combined.

As well as dead plants, peat contains so-called ‘Black Carbon’; that is carbon captured following moorland burning. In the UK, The British Geological Survey are researching how this and other soil carbons behave, and their likely impact on climate change. Only last month, a fascinating paper in Nature Geoscience highlighted how inaccurate knowledge about the ratio of soil black carbon to organic carbon in Australia – with implications on the global scale – can result in significant (almost 25%) over-estimation of CO2 release from global warming feedback mechanisms. On a planet-wide scale, the possible swings are massive.

So – back to what we can do. First, don’t forget its not just about climate change. Peat bogs in the UK are also an important habitat for wildlife and a source of colourful diversity for us humans. I’ve passed many a happy hike literally bouncing along on Peak District peat.

You might like to get involved in one of the remediation efforts run by the National Trust. And if you’re a domestic gardener – as a group consuming seventy percent of horticultural peat in the UK, and all from drained bogs that are killed in the process of its extraction – you can make a direct impact by simply not using it. And, as the UK accounts for 8% of the world’s northern peatlands, collectively holding 30% of all soil-based carbon, you have the potential to make a real global impact in your own back garden – as it were. The golden rules are:

  • Don’t buy peat
  • Only buy pot plants bedded in non-peaty compost
  • Quiz your garden centre on its compost/peat policy; share this article!
  • Support local wildlife trusts who are working to regenerate degraded mossed areas
  • Encourage your family and friends to do likewise
  • And write to your MP

Lastly, if you want to get more involved on the policy and campaigning side, get in touch with The Peatlands Campaign Consortium, who have been a major influence on the government in setting targets for reduced peat use.