We’re all becoming more and more aware of our personal carbon footprint and how it impacts the world and there are many ways that governments around the world are trying to reduce their own emissions, whether that’s investing in renewable energy or trying to cut the number of vehicles on the roads of their cities.
Another solution for some has been by planting trees, as trees naturally absorb harmful carbon dioxide and it’s estimated that for every five trees planted, one ton of carbon dioxide is absorbed.
So, bearing this in mind, how many trees would major cities around the world need to plant each year to offset their carbon footprint? And how does this look around the UK too?
Each of the capital cities that would need to plant the most trees were found in Asia, with Beijing having the highest emissions by some way, emitting 75 million tons annually. Over 15 million trees would need to be planted to offset this amount.
This was followed by two city-states, Singapore and Hong Kong, which would need to plant 9.4 million and 9 million trees respectively to reach carbon neutrality.
However, not all cities around the world have to embark on such a tree-planting spree. Reykjavík only emits just under 350,000 tCO2 a year, which means that it would only need to plant around 70,000 trees to offset its footprint (which is admittedly still a lot of trees!).
This was followed by New Zealand’s capital, Wellington, and Basel in Switzerland, which would need to plant 124,236 and 156,786 trees to offset their emissions respectively.
Looking here in the UK, North Lincolnshire is the local authority with the greatest emissions (7.4 million tCO2 annually) and therefore would need to plant the most trees to offset this footprint with 1.49 million trees a year. Scunthorpe in North Lincolnshire is home to the Tata-owned Appleby-Frodingham steel plant, which is one of the largest and most successful steelworks in Europe.
Neath Port Talbot in Wales, which is home to one of the country’s biggest steel making plants came in second, and the UK’s second-biggest city of Birmingham in third.
Emissions for global cities were sourced from the Global Carbon Atlas Global City Emissions dataset and refers to “Scope-1 emissions” which includes transport, industrial, waste and local power plants emissions within the city boundary.
We looked at capital cities for which emissions data were available, with the exception of Canada, Italy and Switzerland, where data for the capitals was unavailable so the cities of Toronto, Milan and Basel were used instead.
2018 Emissions for UK local authorities were sourced from the Department for Business, Energy & Industrial Strategy’s UK local authority and regional carbon dioxide emissions national statistics: 2005 to 2018.
Tree offset calculation is based on Carbonify.com’s carbon dioxide emissions calculator, which assumes that for each ton of CO2 produced, five trees need to be planted, on the basis that a tree planted in the humid tropics absorbs on average 50 pounds (22 kg) of carbon dioxide annually over 40 years - each tree will absorb 1 ton of CO2 over its lifetime; but as trees grow, they compete for resources and some may die or be destroyed - not all will achieve their full carbon sequestration potential.
Note that due to being sourced from two different datasets, the figures shown for London in the global breakdown and the combined total of the London boroughs in the UK breakdown differ slightly.