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Published by Patricia Lustig on

We are ready to send out the first draft to people who have volunteered to review the book for us on MONDAY! There are examples of opportunities for each megatrend and here is an example to help with Global Warming (with thanks to Professor Sebastien Balibar who helped with the calculations)

How many trees does it take to offset your commute?

In each chapter, for each megatrend, there is a section on what people and organisations can do to adapt or find opportunities. This is one of the questions we asked; the answer is about 22 trees. The calculation (including assumptions) is follows.

We assume that a person commutes 20 km a day (10km each way). They work 250 days a year, which means the commuting distance is 5000 km a year.

A typical car emits 130g CO² per km which means the commute emits 650 kg CO2 per year.

The average absorption per tree is about 30 kg of CO2 per year which means it will take 22 trees to compensate for the emissions of one year’s commute of 20 km per day.

A tree needs about 9 m² space to grow, so 22 trees need 200 m² or half an acre. If you planted 22 trees, your commute would be offset every year, the costs being the initial planting and then ongoing woodland management.

Planting trees is a good answer to offset carbon, but note that it requires land. Probably land that can’t be used for crops, but nonetheless, there are always trade-offs.

Tree planting can displace crops; different trees and different climatic conditions lead to different absorption levels. Although there are many factors contributing to the absorption by trees – like type of leaf, growth rate, climatic conditions – there is overwhelming consensus that trees are good for the climate.

The CO2 emissions of vehicles could be significantly reduced – consequently we may not need to increase the tree cover as much as we think today. If petrol/diesel consumption is reduced due to more efficient combustion engines and a greater percentage of vehicles are electric (keeping in mind how the electricity is produced), fewer trees will be needed to offset the carbon than if emissions remain the same and the number of vehicles continues to grow.

And if you’re interested in reviewing the first draft of Twenty Forty, please contact me at


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