Hansen Global Forest Change

Hansen Global Forest Change (GFC) is an annual global tree-cover change product derived from Landsat imagery at 30 m native resolution, distributed by the University of Maryland under CC BY 4.0. The product is available via Google Earth Engine and Google Cloud Storage as unsigned 8-bit GeoTIFFs tiled at 10 x 10 degree blocks^[1][2]. The originating methodology was published in Hansen et al. 2013^[3].

The v1.13 release (2000-2025) encodes annual loss year as integer values 1 to 25 representing 2001 to 2025^[1]. Prior versions (v1.12 and earlier) used values 1 to 24 for 2001 to 2024^[4]. The gain layer captures forest gain from 2000 to 2012 and has not been updated in any version since initial release^[2].

Tree cover loss is defined as stand-replacement disturbance regardless of proximate cause (plantation clearing, agricultural conversion, fire, selective logging) and is not equivalent to permanent deforestation^[1]. Processing for the post-2011 period was reprocessed in recent versions using improved training data and sensor quality assessment; the pre-2011 data retains the original algorithm and has lower sensitivity to smallholder clearing, boreal fire loss, and short-cycle plantation disturbance^[2]. Users comparing rates across the pre-2011 and post-2011 boundary are advised to account for the methodological discontinuity.

The product underpins the Global Forest Watch platform, the GLAD-L and RADD alert systems, and serves as a reference baseline for REDD+ and supply-chain due-diligence frameworks^[1]. It is reported as a relative indicator of spatiotemporal trends and is not intended as a definitive area measurement for regulatory reporting^[2].