Tuesday, 1 June 2021

Some worrying statistics....

For some time now and in quite a few messages I have mentioned global warming and the how’s and why’s. There should be no doubt that it is humanity’s fault. Yes, you and me! We are very quickly destroying the only place where we can live. If you do not think so I refer you to plenty of web research about CO2. I was astounded by how ill-informed I was. The Carbon Independent.org website shows why. Apparently the Paris agreement (Google that if you haven’t a clue) assumes greenhouse gas emissions of a quarter of a tonne of CO2 per hour flying. So, if you use air-planes to go on holiday and care about children, future generations, and social justice, and want to stay within the personal lifetime carbon budget of 50 tonnes CO2, flying is likely to be unaffordable, and therefore need to stop flying for the time being. (The limit of 50 tonnes CO2 per person is a figure compatible with the Paris Agreement.)

A Boeing 737-400 jet is typically used for short international flights. For a distance of 926 km, the amount of fuel used is estimated to be 3.61 tonnes , including taxiing, take-off, cruising and landing. Using a seating capacity of 164 [Wikipedia, viewed 28.2.08] and an average seat occupancy (or 'load factor') of 65%, this gives a fuel use of 36.6 g per passenger km. Another website (https://micpohling.wordpress.com/2007/05/08/math-how-much-co2-released-by-aeroplane/) has worked out that 2.6kgs of CO2 is produced per litre.

Jet engines as used by the 737 (and 747) use approximately 4 litres every second, so 14,400 litres an hour. Per hour that means 37.5 tonnes of CO2 are produced. Say, two hours to Spain therefore 75 tonnes of CO2 per flight. Per passenger if full, 75 tonnes/170= 441kgs of CO2. Your holiday puts 1 tonne of CO2 on your personal balance! So, the average family of 4 have produced 4 tonnes of CO2. Even if you planted a tree to offset this you would need to plant 4 trees per person every year! A native broadleaf tree is estimated to take up 1 tonne of CO2 during its life time (about 100 years). With figures such as these you can see the damage done by flying air-planes, even to just go on a holiday. 

There seems to be a strange misunderstanding between scientists as to how much CO2 is produced by jet engines. I have a printed out conversion table which is produced by the University of Exeter. That says that short-haul flights is deemed to use 0.18 kgs per passenger per kilometre. This sounds pretty close to the truth. So, you can work out short haul costs to the environment.

And just in case you did not think car driving is so bad, the average diesel pours 12kgs of CO2 into the atmosphere per 100kms. My workplace is 23 miles from where I live, that is about 36kms. I calculate that with stopping and starting in the busy traffic I have put some 15kgs of CO2 in the air. Petrol is worse, the average petrol car puts 20kgs per 100kms!

If we use the average of 16kgs per 100kms over all and multiply that by the average number of cars on the road (the RAC has calculated some 15 million people – this might be 15 million cars but some will have more passengers. Averaging out to 10 million cars. The average length of a commuter trip by car/van varies little across English regions and Wales at about ten miles. It is highest in the South East (11.2 miles) and lowest in London (8.6 miles).

So, averaging it all out we arrive at 1.6kgs of CO2 per 10 miles x 10,000,000 cars. Therefore on a daily basis we can pump some 16,000 tonnes of CO2 into the air in Britain alone! As these are averages there will be days it is less but also days it will be vastly more!

All these figures are easily obtainable from the Web. Just as I have done. Now we know why we are in trouble.

Edit - I think scientists use different techniques and possibly use data from manufacturers but I believe the University of Exeter seems to be the more correct.

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