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Carbon emissions and removals from forests: new estimates, 1990–2020
oleh: F. N. Tubiello, G. Conchedda, N. Wanner, S. Federici, S. Rossi, G. Grassi
Format: | Article |
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Diterbitkan: | Copernicus Publications 2021-04-01 |
Deskripsi
<p>National, regional and global CO<span class="inline-formula"><sub>2</sub></span> emissions and removals from forests were estimated for the period 1990–2020 using as input the country reports of the Global Forest Resources Assessment 2020. The new Food and Agriculture Organization of the United Nations (FAO) estimates, based on a simple carbon stock change approach, update published information on net emissions and removals from forests in relation to (a) net forest conversion and (b) forest land. Results show a significant reduction in global emissions from net forest conversion over the study period, from a mean of 4.3 in 1991–2000 to 2.9 Gt CO<span class="inline-formula"><sub>2</sub></span> yr<span class="inline-formula"><sup>−1</sup></span> in 2016–2020. At the same time, forest land was a significant carbon sink globally but decreased in strength over the study period, from <span class="inline-formula">−3.5</span> to <span class="inline-formula">−2.6</span> Gt CO<span class="inline-formula"><sub>2</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>. Combining net forest conversion with forest land, our estimates indicated that globally forests were a small net source of CO<span class="inline-formula"><sub>2</sub></span> to the atmosphere on average during 1990–2020, with mean net emissions of 0.4 Gt CO<span class="inline-formula"><sub>2</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>. The exception was the brief period 2011–2015, when forest land removals counterbalanced emissions from net forest conversion, resulting in a global net sink of <span class="inline-formula">−0.7</span> Gt CO<span class="inline-formula"><sub>2</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>. Importantly, the new estimates allow for the first time in the literature the characterization of forest emissions and removals for the decade just concluded, 2011–2020, showing that in this period the net contribution of forests to the atmosphere was very small, i.e., a sink of less than <span class="inline-formula">−0.2</span> Gt CO<span class="inline-formula"><sub>2</sub></span> yr<span class="inline-formula"><sup>−1</sup></span> – an estimate not yet reported in the literature. This near-zero balance was nonetheless the result of large global fluxes of opposite sign, namely net forest conversion emissions of 3.1 Gt CO<span class="inline-formula"><sub>2</sub></span> yr<span class="inline-formula"><sup>−1</sup></span> counterbalanced by net removals on forest land of <span class="inline-formula">−3.3</span> Gt CO<span class="inline-formula"><sub>2</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>. Finally, we compared our estimates with data independently reported by countries to the United Nations Framework on Climate Change, indicating close agreement between FAO and country emissions and removals estimates. Data from this study are openly available via the Zenodo portal (Tubiello, 2020), with DOI <a href="https://doi.org/10.5281/zenodo.3941973">https://doi.org/10.5281/zenodo.3941973</a>, as well as in the FAOSTAT (Food and Agriculture Organization Corporate Statistical Database) emissions database (FAO, 2021a).</p>