The importance of the land use, land-use change and forestry sector (which is often referred to as LULUCF) is reflected in 118 of 143 countries including land-based emissions reductions and removals in their latest emissions pledges under the Paris Agreement.
However, there is a complication.
It arises because of a fundamental difference in how land-based emissions are treated by scientific models and the national greenhouse gas inventories submitted by parties to the UN Framework Convention on Climate Change (UNFCCC).
Specifically, there are different definitions as to what constitutes “managed” land and the human-caused carbon removals on that land.
As we show in our new study, published in Nature, the result is a gap of 4-7bn tonnes of CO2 (GtCO2) between estimates from models and national inventories for net emissions from current land use. Even at the low end of this range, it equates to around 10% of global annual CO2 emissions today.
The knock-on impact of this gap is that it makes comparisons between the two difficult in critical policy processes such as the global stocktake – the five-yearly progress check on collective action towards the long-term goal of the Paris Agreement.
And, more fundamentally, our findings suggest that nations will need to increase the collective ambition of their climate targets to remain consistent with the Paris temperature limits.
In this guest post by Matthew J Gidden (IIASA), Thomas Gasser (IIASA) and Giacomo Grassi(JRC) published by Carbon Brief the choices made about how land is used and managed as a key component in tackling climate change are examined.