Technical Comments

Response to Comment on “Tropical forests are a net carbon source based on aboveground measurements of gain and loss”

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Science  11 Jan 2019:
Vol. 363, Issue 6423, eaat1205
DOI: 10.1126/science.aat1205


  • Fig. 1 Comparison of spatial patterns in Hansen et al. and Baccini et al. datasets.

    (A) Digital Globe image (2013) of shifting cultivation in South Kivu province, Democratic Republic of Congo, with Baccini et al. 21.4-ha pixel boundaries shown in red. (B) Hansen et al. 30-m forest area loss pixels (2003–2014) shown in black. (C) Baccini et al. carbon density change (2003–2014) pixels with loss values in Mg ha−1 shown in white. (D) Combination of (B) and (C). Hansen et al. losses (black) inside Baccini et al. pixels (red) can and do agree in terms of overall trend (four eastern pixels); however, depending on the underlying pattern of land use, below some threshold of loss, carbon density change tends toward zero (net neutral; two western pixels) because gains are observed to be equivalent to losses over time. Hence, Hansen et al. records gross forest area loss, whereas Baccini et al. records no net carbon density change.

  • Fig. 2 Agreement between Hansen et al. and Baccini et al. data products.

    Tropical America, Africa, and Asia (top to bottom), expressed as a percentage for Baccini et al. loss pixels having ≥90% of forest area loss as determined by Hansen et al.

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