Fragmentation outweighs forest cover in shaping land surface temperature across half of global forests

Forests are widely recognized for their significant role in climate change mitigation. Global landscape-scale assessments have focused mainly on how forest cover (FC) affects temperature. Yet, changes in forest area are generally accompanied by altered fragmentation, and both the independent effect of fragmentation on forest thermal environments and its contribution relative to FC remain insufficiently understood. We disentangled the respective relationships of fragmentation and FC with land surface temperature (LST) across the globe. Except in boreal zones with a mean annual air temperature below 0°C, LST was positively associated with forest fragmentation. In 48% of global forests, the influence of fragmentation on LST predominated over that of FC exerting an effect averaging 3.23 times as large. In particular, tropical forest loss typically coincided with increased fragmentation, jointly contributing to amplified warming. Our findings highlight that forest fragmentation should be considered alongside FC when assessing the climate benefits of global forests, and that optimizing landscape configurations could enhance the effectiveness of forestry policies in achieving climate goals.