How Many Trees Are Needed To Capture Car Emissions
Lots and lots, and here is how I worked it out. Not to mention way too many numbers.
Over a 40 year period, a typical European forest will capture 200 tonnes of carbon dioxide per hectare. That is 5 tonnes a year.
Cars, and just cars, account for 43.7% of all transport carbon dioxide emissions in the EU, which works out as 20% of all EU emissions. In 2017 EU carbon dioxide emissions were 4,333 million tonnes. So our cars account for 867 million tonnes.
With around 350 million cars in the EU, that is about 2.5 tonnes of carbon dioxide per car, per year.
So one hectare of forest can absorb 2 cars worth of carbon dioxide. A hectare is a gnats under 2.5 acres, so Jeremy Clarkson’s 1000 acres farm can, if it was planted as all new forest, counteract the carbon dioxide from 800 cars per year. That should make him smile.
A lovely oak forest
How many trees grow on a hectare of land. This does depend on the type of tree but the NHS Forrest website quotes between 1000 and 2500. The difference in numbers does not greatly change the amount of carbon dioxide absorbed, just that some trees are tall and thin, others are wide and short, while others are leafy at the top, and others at the bottom.
A hectare is 10,000 square metres, so picking the lower number, as it is easier to plant one tree than 2, each tree needs 10 square meters, which means I can just about squeeze 3 trees into my garden. I have one, a very sick looking cherry tree. But if I did plant 3 trees, I could, once they had matured, absorb about 15 kg of carbon dioxide a year.
Now my old Ford diesel produces 143 g of carbon dioxide per mile (223 g/km). Simply dividing 15 kg by 0.143 kg gives 105. That is how many miles I could drive in a year if I wanted my trees to absorb all the carbon dioxide.
Thing is, I drive about 25,000 miles a year, so I need a garden of mature trees that is 240 times bigger, or 7,150 square metres, which is, in Majestic units, 1.8 acres.
That is not that large, and most people do a third of the mileage I do, so 0.6 of an acre per car. Taking just the UK, which has around 31 million cars, we would need to plant 7,380,952 hectares of new forest. That is 30% of the United Kingdoms land area.
Consequence of high temperatures