Global forest maps show shocking disagreement, threatening climate and conservation goals

Where exactly are the world’s forests? This seemingly straightforward question has a surprisingly complex answer that could undermine global environmental efforts. A groundbreaking study reveals that widely used forest maps disagree so dramatically that they identify completely different areas as forested land across much of the planet.

Researchers compared ten major global forest datasets that rely on satellite imagery to track Earth’s forests. These maps form the backbone of critical environmental work, from calculating carbon storage to identifying biodiversity hotspots and directing conservation funding. The results were alarming: across all areas identified as forest by at least one dataset, only 26% received unanimous agreement from all maps. Even after adjusting for technical differences, the maps still showed massive disagreements about where forests actually exist.

The confusion stems from fundamental differences in how scientists define and measure forests. Some maps count areas with just 10% tree cover as forest, capturing savannas and scattered woodlands, while others require 70% canopy coverage, focusing only on dense forests. Technical factors like satellite resolution, imaging sensors, and data processing methods create additional variations. High-resolution imagery can spot narrow forest strips that coarser satellites miss entirely.

These discrepancies have serious real-world consequences. Climate agreements, conservation strategies, and billions in development spending all depend on accurate forest mapping. When the maps disagree about basic forest locations, it becomes nearly impossible to set meaningful targets or measure progress toward global environmental goals.