Assumptions that tropical forest canopies protect from the effects of climate change are unfounded, say researchers. Crucial strongholds for biodiversity are under threat as temperatures are rising in tropical forests, the world’s most diverse terrestrial ecosystems, a new study reveals. It has been long assumed that the forest subcanopy and understorey – where direct sunlight is reduced – would be insulated from the worst climate change impacts by the shielding effect of the forest canopy. A new study, published in the journal Nature Climate Change, used a microclimate model to examine temperatures beneath the rainforest canopy across the global tropics. This showed that between 2005 and 2019, most of the world’s undisturbed tropical forests experienced climate conditions at least partially outside the range of historic conditions. Many areas had transitioned to almost entirely new temperature averages.