Planting 20,000,000 Trees: breakthrough or distraction?

This article factually discusses what is the potential of planting 20 million trees as CO2 sequestration vs world emission. In a bonus, I give an indication of how much trees you should be planting every year to compensate your CO2 footprint.

Disclaimers: I am not a tree expert, I just like them as much as I like order of magnitude calculations.

Planting 20,000,000 Trees vs World CO2 Emissions

As you may have seen in the news, the YouTuber MrBeast has launched a fundraising action for which every dollar raised allows to plant one tree. The objective is to plant 20 million trees before 2020! Many other youtubers and influencers have followed the trend, and as I am writing these lines (in four days), 7 millions trees have already been financed for plantation. I was so impressed that I wanted to know how much of our CO2 emissions, such successful action, would be capable to compensate for. For that, I have only made hands calculations with rough order of magnitude (ROM), but I believe it is sufficient to appreciate the level of significance of this #TeamTrees action.

Let's start with the world CO2 annual emissions which are in the order of 36 Gigatons of CO2. We assume that one mature tree can capture between 0.5 and 1 ton of CO2 over its lifetime [1]. Also, let's introduce a tree survival rate until maturity ranging from 0.4 worst case to 0.8 best case [2].

[1] Afzal & Akhtar (2013):1 ton is taken as best case scenario where 773 40-year old trees have sequestrated 850 tons of CO2. 0.5 tons is taken as a low bound for our worst case scenario.

[2] arbitrary yet realistic guesstimate

It means that over their lifetime, those 20,000,000 planted trees would potentially be able to capture between 4 and 16 millions tons of CO2. This represents roughly 1/1000th of the world annual emissions, or in other worlds:

20,000,000 planted trees could capture the equivalent of a few hours of the world CO2 emissions*.

*according to the above mentioned hypothesis: between 1 and 4 hours at the current CO2 emission rate.

The computation spreadsheet can be accessed here

This may be surprising. Did you expect more, or less? My personal aprioris was that this would have been equivalent to a couple of minutes of the world CO2 emissions. So I am positively surprised! For sure we did not discuss all the means necessary to plant grow the tree from seeds to ready-to-plant, the human and machine workforce, the numeric impact of the foundering via video etc, but that's out of scope here!

A constraint that you probably think of is the surface necessary to plant and grow all these trees. Depending on the type of tree we can assume a 4 to 10 m diameter of the canopy which means that the overall 20 million trees would occupy a surface ranging from 250 km2 (similar to Paris) to 1500 km2 (size of the Great London). However, the apparent planting density in MrBeast's video seems higher than the one proposed. This would reduce the overall surface coverage, but is likely to affect the long term tree development capabilities and therefore their total CO2 sequestration potential, rendering the worst case more likely.

The surface required to plant these 20 millions of trees is in the order of a large city such as Paris or London

At this point you may think that this is a lot of space and a lot of work only to compensate for a couple of hours of world CO2 emissions, and you are right. By the time I will finish to write these lines, another 20 millions of trees would be needed; i.e. another area of the size of a country capital to be reforested. It allows to appreciate the challenge we are facing today, and that it is not only by planting trees that we'll get out of this, despite all the credits such action deserves.

In addition, it is worth mentioning that reforestation, if intelligently engineered, have other non-negligible benefits. In particular, I am thinking of multi-layers agroforestry systems: for lots of temperate regions, they are the state towards which conventional agricultural field will spontaneously evolve: i.e that we do not need to constantly utilise energy to keep the place out of its spontaneous evolving state (being the forest) in favor of intensive and monocultures. Agroforestry systems are robust and resilient to disasters and extreme climate events. Also they could, in case of crisis, secure to some extent basics needs for construction materials, food, medicinals, thanks to the large diversity of product that can be harvested. Also, there are great places for biodiversity.

II - How much trees you should plant to compensate for your CO2 emissions?

If you are a French citizen, to compensate for the 4.5 tCO2/yr/pc you would need to plant at least 23 trees each years to be taken seriously. But we, French, are not clean: lots of people complain against nuclear power, so let's have a look at some other people. For example, some who are good at doing business, the British.

If you are a UK citizen, you may need to plant actually more trees to compensate for the 6.5 tCO2/yr/pc. So not good enough? Let's check the germans, because they are well-known to be organized and supposedly full of renewable energies.

If you are a German citizen, you may be required to plant 45 trees every year !! this to compensate for the 8.9 tCO2/yr/pc.

But worst, for US citizens, 80 trees should be planted to compensate for their 16 tCO2/yr/pc.

NB: if you are frequent flyer with airlines, you can safely multiply this number by a factor 2.

Now, I must admit that I am surprised by these numbers. I expected much higher numbers. But this is good enough.

On average europeans should plant 10 to 50 trees every year to compensate for their CO2 emissions.

If you are 30 years old and if you haven't taken any serious action yet to help fight climate change: why wouldn't you donate 30*50 dollars to plant 1500 trees to pay your debt towards the Earth?

To plant trees:

And if you haven't seen the launch video from MrBeast: here it is: