Climate change has emerged as the single greatest threat to the world’s natural World Heritage sites, affecting nearly half of them, according to the IUCN World Heritage Outlook 4 released at the IUCN Congress in Abu Dhabi. The report warns that 43% of natural sites now face severe climate-related risks, surpassing all other pressures, while invasive alien species impact 30% of sites. The number of sites affected by wildlife and plant diseases has also increased sharply, rising from 2% in 2020 to 9% in 2025.
The Outlook, based on a decade of global assessments since 2014, provides the most comprehensive analysis of the state of natural World Heritage sites to date. It reveals a continuing decline in their conservation status, with the proportion of sites showing a positive outlook falling from 62% in 2020 to 57% this year. Areas recognised for their biodiversity are among those most at risk.
“Protecting World Heritage is not just about safeguarding iconic places , it is about protecting the foundations of life, culture, and identity,” said Dr. Grethel Aguilar, IUCN Director General. “The findings show that threats are rising, and stronger collective action is needed to ensure these irreplaceable treasures endure for future generations.”
The report calls for urgent investment in climate adaptation, stronger governance, and greater recognition of Indigenous Peoples’ leadership in conservation efforts to build resilience across the world’s natural heritage landscapes.