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?
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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'.
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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).
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Here are the 27 scenarios with afforestation separated, & deforestation back calculated. There are quite some different dynamics, depending on the model.
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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).
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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?
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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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The US & EU have had large drops in coal CO₂ emissions per capita over the last decades. They have stable energy use & aging coal infrastructure, so new energy sources displace coal.
India is still growing from very low energy per person, & has a young coal fleet.
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Oil CO₂ emissions per capita are very low in developing countries, particularly India. The US & EU are struggling to reduce oil use.
You may have heard that after revisions to land-use change emissions, total global CO₂ emissions are approximately flat over the last decade (black line).
But, how much do we revise carbon budget components each year?
Let's have a look...
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Fossil CO₂ emissions are revised each year, particularly the last decades. We update data & improve methods. Chinese data has had major revisions & cement was completely revised in 2018, plus lots of smaller improvements.
Land-use change (LUC) emissions are much more uncertain:
* 2014-2015: one bookkeeping model used
* 2016-2019: two bookkeeping models used
* 2020-2021: three bookkeeping models used
* 2021: major update of land-use forcing (change) datasets
After dropping 5.4% in 2020, global fossil CO₂ emissions are expected to increase 4.9% [4.1-5.7%] in 2021, finishing just 0.8% below 2019 emission levels.
"Everyone wants to keep the dream of 1.5°C alive. In every practical sense you are kidding yourself if you think that we are remotely heading towards 1.5°C"
The UNFCCC Synthesis Report says NDCs will lead to a 5% rise in emissions from 2019 to 2030. This is 16% above 2010 levels, as opposed to ~50% below as required for <1.5C. unfccc.int/news/updated-n…