Thread by @Peters_Glen

What do 𝑛𝑒𝑡 CO₂ emissions from land-use change do in 1.5°C scenarios?

On a net basis, CO₂ emissions reach net zero around 2030. But, this is all net, so is that reduction because of reduced deforestation or increased afforestation?

1/

Of the 53 1.5°C scenarios with no or low overshoot, 27 of them report afforestation.

It is unclear if the 'afforestation' variable is defined consistently with the LUC emissions, but if we assume it is then we can therefore define the difference as 'deforestation'.

2/

All scenarios have reduced deforestation, but do not drop to zero (median in 2100 is 0.5GtCO₂/yr). The negative values from C-ROADS are likely a reporting error.

Afforestation has a median of 4GtCO₂/yr, but clearly afforestation is defined differently in models (see 2010).

3/

Here are the 27 scenarios with afforestation separated, & deforestation back calculated. There are quite some different dynamics, depending on the model.

4/

Overall, the scenarios that have afforestation reported have lower net CO₂ emissions from LUC, suggesting that the afforestation values may not be representative of all models. However, removing REMIND & POLES brings the medians together (in different time periods).

5/

I am not sure if it is consistent to separate afforestation & deforestation this way using the SR15 database, it is quite difficult to understand if the reported variables can be treated that way, @daniel_huppmann?

6/

Afforestation has one of the biggest potentials for Carbon Dioxide Removal, but we don't have much good information on it!

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