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New research quantifies climate benefits from UNESCO World Heritage forests

Thursday, 28 October 2021 at 0:01
access_time 6 min read
Yosemite National Park (United States of America) © David Geldhof

World Heritage forests: Carbon sinks under pressure, a report by UNESCO, World Resources Institute (WRI) and International Union for Conservation of Nature (IUCN) released today, provides the first global scientific assessment of greenhouse gas emissions and sequestration by forests in UNESCO World Heritage sites.

It reveals that despite substantial carbon stored and absorbed by forests across UNESCO’s World Heritage network, the climate benefits of even some of the world’s most iconic and protected forests are under pressure from land use and climate change. For example, over the past 20 years, World Heritage sites lost 3.5 million hectares of forest (an area larger than Belgium) and forests in 10 World Heritage sites emitted more carbon than they absorbed. Continued reliance on these forests’ carbon sinks and storage depends on improved forest protection.

World Heritage forests:
Carbon sinks under pressure

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Quantifying climate benefits from UNESCO World Heritage forests

Forests contribute to the global climate system by both emitting and absorbing carbon dioxide (CO2) from the atmosphere. However, our understanding of the transfer of CO2 between forests and the atmosphere at specific locations has often been hampered by a lack of data. Newly available maps of how much carbon forests absorbed and released between 2001 and 2020 allow more localized estimation of the carbon emitted from and sequestered by forests. Combining these maps from research led by the World Resources Institute with site-level monitoring information from the state of conservation reporting process of the World Heritage Convention and the IUCN World Heritage Outlook of 2020, the gross and net carbon absorbed and emitted by UNESCO World Heritage forests between 2001 and 2020 have been estimated for the first time and the causes of emissions from some sites determined. 

UNESCO World Heritage forests are strong carbon stores and sinks

The new analysis estimates that UNESCO World Heritage forests, which cover 69 million hectares, or roughly twice the size of Germany, hold 13 billion tonnes of carbon (Gt C) in vegetation and soils. This exceeds the amount of carbon in Kuwait’s 101 billion barrels of proven oil reserves. The majority of the World Heritage forest carbon is stored in tropical sites.

Although stable carbon storage is important, the carbon emitted and captured by forests more directly affects climate change. The new report estimates that forests across World Heritage sites removed approximately 190 million tonnes of CO2 per year between 2001 and 2020 from the atmosphere. This is equivalent to roughly half of the United Kingdom’s carbon emissions from fossil fuels in 2019. Ten large sites were responsible for half of the World Heritage network’s total net carbon sink, but even sites that are smaller total sinks (absorbing less carbon dioxide overall) can play a considerable role in regional and local climate regulation. In fact, an average hectare of World Heritage forest at 55 sites can absorb in one year the same amount of carbon that a passenger vehicle emits.

Notes: The classification of some sites as neutral, sinks (sequestration > emissions) and sources (emissions > sequestration) is different between the two maps because of the cut-offs between categories. Forest cover is tree cover in 2000 from Hansen et al., 2013.

As some of the world’s best protected forests, it is alarming that World Heritage sites lost 3.5 million hectares of forest (more than the area of Belgium) between 2001 and 2020 and that forests in 10 World Heritage sites emitted more carbon than they absorbed. Concerning patterns of emissions were not restricted to those 10 sites, however. Other sites, despite remaining net carbon sinks overall, showed spikes or clear upward trajectories in emissions that threaten the strength of the future sink.

According to information from the reactive monitoring process of the World Heritage Convention and the IUCN World Heritage Outlook of 2020, the two most widespread threats to UNESCO World Heritage forests are climate change with associated severe weather (e.g. fires, storms, floods, droughts, temperature extremes, and habitat shifting/alteration) and land-use pressures associated with various human activities such as illegal logging, wood harvesting, and agricultural encroachment due to livestock farming/grazing and crops. These types of pressures are each reported in about 60% of World Heritage sites.

Pathways to protect UNESCO World Heritage forests and maintain their climate benefits

While diverse interventions are needed to address all threats to UNESCO World Heritage forests, three distinct pathways for action emerge to secure these forests as carbon sinks for future generations against severe weather events and land-use pressures.

1. Rapid and effective responses can help prevent devastation from climate-related events

When climate-related events like extreme fires occur, precious days are often lost in organizing an emergency intervention due to lack of funding and reliable data, while during this time, extensive emissions can be released. Some World Heritage sites have already taken steps to better manage climate-related risks by adopting climate change adaptation plans (e.g. Wet Tropics of Queensland in Australia and Mount Kenya National Park/Natural Forest in Kenya), implementing integrated fire management programmes (e.g. Cerrado Protected Areas: Chapada dos Veadeiros and Emas National Parks in Brazil), and supporting disaster risk reduction initiatives through coastal protection and flood regulation (e.g. The Sundarbans in Bangladesh and Sundarbans National Park in India). However, the number of World Heritage sites with established policies, plans or processes for managing or reducing risks associated with disasters remains low.

2. Support mechanisms that maximize intactness and connectivity of forests

Protecting sites’ broader landscapes protects the sites themselves. Most pressures to World Heritage sites originate outside their boundaries, where forest protection is weaker. The fragmentation of the forest landscape around sites can generate increased carbon emissions and disrupt ecological connectivity with implications for broader ecosystem functioning (e.g., tree mortality, movement of species, etc.) and the stability of carbon stocks. Integrated landscape management and creation of ecological corridors and buffer zones are therefore necessary to ensure that sites’ ability to store and sequester carbon is preserved. The creation of buffer zones is specifically recommended in the guidelines for nomination and management of World Heritage sites. In addition to adding a layer of protection to sites, they can act as net carbon sinks themselves. For example, the net carbon sink of Sangha Trinational buffer zone is more than twice as large as the site itself.

3. Integrate World Heritage sites into climate, biodiversity, and sustainable development agendas

With the interaction between global climate change and increasing local human pressures, coordinated action is needed at all levels. Explicitly including World Heritage sites in countries’ national policies can contribute to international initiatives, such as the Sustainable Development Goals, climate action plans (e.g., Nationally Determined Contributions under the Paris agreement), and biodiversity strategies under the Post-2020 Global Biodiversity Framework, as they have the inherent potential to serve as living laboratories and influence policy development. For example, Gabon’s research programme at Lope National Park since the early 1980s has underpinned many of the country’s conservation- and climate-related national policies. The subsequent implementation of such policies led Gabon to become the first country in Africa to receive results-based payments for reduced emissions from deforestation and forest degradation in 2021.


UNESCO World Heritage forests can continue to be reliable carbon sinks if they are effectively protected from local and global threats. The high profile, global reach, and inspirational power of World Heritage sites underpin a strong case for action. The successful implementation of actions to protect these forests requires the mobilization of key stakeholders (e.g., governments, civil society, Indigenous Peoples, local communities and the private sector) to develop sustainable financing and investments and promote interdisciplinary knowledge-sharing for decision-making.

By Tales Carvalho Resende (UNESCO), David Gibbs (WRI), Nancy Harris (WRI), Elena Osipova (IUCN), authors of the report ‘World Heritage forests: Carbon sinks under pressure