Comment on Otón et al. Analysis of Trends in the FireCCI Global Long Term Burned Area Product (1982–2018). Fire 2021, 4, 74

Abstract

In a recent study, Otón et al. [1] compared trends in global burned area (BA) mapped by the ESA Climate Change Initiative (CCI) MODIS-based FireCCI51 and AVHRR-based FireCCILT11 data sets. As noted by the authors, the two data sets were expected to be consistent, since the former was used to train the classification algorithm that generated the latter. To help establish this expected consistency, Otón et al. [1] examined the correlation between the respective gridded annual BA time series for the common 2001–2018 period, from which they concluded that “High spatial correlations are displayed with Pearson correlation (r) > 0.75 in pixels of all regions”. However, the authors overlooked several extensive zones in Africa where the BA time series were inconsistent and poorly correlated. The presence of these low-correlation zones notwithstanding, Otón et al. [1] reported widely predominant spatial agreement and only minor disagreement in BA trends for the 2001–2018 period. In this study, we explore inconsistencies between the FireCCI51 and FireCCILT11 BA in Africa, over zones that collectively encompass nearly one third of the entire continent. In addition, we note that the spatial extent over which FireCCI51 and FireCCILT11 BA trends do not agree was significantly larger when a more appropriate and less selective criterion for trend consistency was used.