Impact on natural World Heritage
Climate change continues to affect more and more natural World Heritage sites. It has now become the most prevalent threat to these sites, according to the IUCN World Heritage Outlook, which tracks the conservation of all natural World Heritage sites.
The IUCN World Heritage Outlook 3, published on 2 December 2020, assesses climate change as a high or very high threat in 33% (83 out of 252) of natural World Heritage sites – up from 26% in 2017 (62 out of 241), and from 15% in 2014 (35 out of 228 sites listed at the time). Invasive alien species, which was assessed as the top threat both in 2014 and 2017, follows closely behind climate change as now the second most prevalent threat to natural World Heritage.
Given the evidence that links the spread of invasive alien species with climate change impacts on ecological parameters, a strong link between these two threats is highly likely. Examples where climate change has facilitated the spread of invasive alien species include Cape Floral Region Protected Areas (South Africa) and Garajonay National Park (Spain).
In some sites, increasing impacts associated with climate change (sometimes accompanied by other threats and issues) have resulted in a deteriorated conservation outlook, as is the case with the Great Barrier Reef (Australia), which is now assessed as having a “critical” outlook. Ocean warming, acidification and extreme weather have contributed to dramatic coral decline in the site, and as a result decreasing populations of marine species.
Climate change is also associated with increasing frequency and severity of fires, as was exemplified by some sites that have faced unprecedented fires in 2019-2020, such as Gondwana Rainforests of Australia (Australia) and Pantanal Conservation Area (Brazil). In some cases the combination of climate change, increasing fires and the associated spread of invasive alien species is already changing the sites’ ecosystems.
In Kluane Lake, located in the Kluane / Wrangell-St Elias / Glacier Bay / Tatshenshini-Alsek World Heritage site (Canada/USA), the rapidly melting Kaskawulsh Glacier has changed the river flow, depleting fish populations. According to a 2019 study co-authored by IUCN, glaciers are set to disappear completely from almost half of World Heritage sites by 2100 if business-as-usual emissions continue.
While only coordinated global efforts can help address the threat of climate change, it is important to increase resilience of threatened sites by limiting other pressures to a minimum.