World Heritage coral reefs likely to disappear by 2100 unless CO2 emissions reduce drastically

During my six years with UNESCO’s World Heritage Marine Programme, I have had the privilege of visiting some of the world’s most beloved ocean places, including Cabo Pulmo, Lagoons of New Caledonia, Belize Barrier Reef, Coiba National Park, Tubbataha Reefs, and the Great Barrier Reef. Field visits are integral to our work, as we are constantly trying to understand the health of these rare places, and forge solutions with local and national governments.

I have had the opportunity to explore thriving coral reefs, treasure troves full of life and breathtaking beauty and color — unlike anything else I’ve experienced. But like many of us, I have also watched with growing unease how the devastating heat wave that gripped the world’s oceans over the past three years wrought havoc in 21 out of the 29 globally-significant reefs on the UNESCO World Heritage List.

Many World Heritage-listed reefs, including Australia’s Great Barrier Reef or Phoenix Islands protected Area in Kiribati, have been working hard to reduce pollution and other stressors and boost resilience. But the record-breaking bleaching event that stretched from 2014 to last month made it clear that local management is no longer sufficient to protect these iconic rainforests of the sea. We are facing a global problem that demands global solutions.

Last month, UNESCO released the first global scientific assessment of climate change impacts on World Heritage coral reefs. While international media has regularly reported on bleaching at the Great Barrier Reef, we knew that was just the tip of the iceberg. The El Nino and climate-fueled temperature spikes that were wiping out corals in Australia were also causing serious damage to reefs in Costa Rica, Mexico, France, the United States, the Philippines, and the Seychelles. And that is just the beginning of the story.

It only takes a spike of 1 to 2 degrees to threaten the health of coral reefs. As seawater heats up, coral animals expel the microscopic algae they rely on for energy. If heat stress lasts too long, and corals don’t reabsorb the algae, they can die. Reefs can recover from bleaching, but it takes 15 to 25 years, and with climate change causing more frequent heat waves, we are approaching the breaking point of these fragile systems.

© The Ocean Agency, XL Catlin Seaview Survey, Richard Vevers and Christophe Bailhache

The global surface temperature is now already up 1°C since pre-Industrial times, and recent El Nino and La Nina events have magnified this effect. The global bleaching event that just ended impacted 72 percent of World Heritage coral reefs, including some of the world’s best-managed reef systems as well as remote sites like Papahānamokuākea (U.S.) and Aldabra Atoll (Seychelles) that are isolated from most human pressures.

Our job at the World Heritage Centre is to support the conservation of World Heritage listed global ocean treasures, and coral bleaching is clearly among the most formidable threats we have faced. In order to understand the scope and severity of the threat, we enlisted the help of international experts from NOAA’s Coral Reef Watch. We used satellite data to analyze past bleaching, and examined two future scenarios to predict how World Heritage reefs will fare based on global carbon emission reduction.

If we don’t dramatically reduce carbon emissions, we could lose every one of the 29 coral reefs on the World Heritage List, devastating the vibrant ecosystems they support, and the human communities that rely on them for food, jobs and flood protection.

The results, detailed in our new report, were sobering. The frequency, intensity and duration of heat stress events has increased with global warming, and we are at a tipping point: if we don’t dramatically reduce carbon emissions, we could lose every one of the 29 coral reefs on the World Heritage List, devastating the vibrant ecosystems they support, and the human communities that rely on them for food, jobs and flood protection.

Wilson Reef © The Ocean Agency, XL Catlin Seaview Survey, Christoph Bailhache

We could see severe bleaching hit icons like the Galápagos Islands and Komodo National Park again within the next five years if emissions continue to climb. Business as usual would cause 25 of the 29 World Heritage reefs to bleach twice per decade by 2040, and all 29 to bleach yearly by the year 2100, meaning they would cease to exist as functioning coral reef systems by the end of this century.

If emissions peak in 2040 and then decline, science predicts we will still see widespread devastation. Under this scenario, 14 of 29 World Heritage reefs would bleach twice per decade by 2040, and all but two would bleach annually by 2100. Warming of 1.5°C is recognized by many scientists as the maximum for coral reef survival, and our research bore this out. Clearly, implementation of the most ambitious target of the Paris Climate Agreement is absolutely essential. Protecting World Heritage reefs will require complementary national and global efforts.

The assessment was launched ahead of the 41st Session in Krakow Poland where the World Heritage Committee expressed the utmost concern about the serious damage World Heritage coral reefs have already sustained due to climate change, and the devastating impacts projected in our new report. The Committee took a strong stance urging State Parties to ratify and uphold the Paris Climate Agreement, and strive to limit global warming to 1.5°C above pre-Industrial levels. Nations around the world are bound by the 1972 World Heritage Convention to support the survival of our shared heritage, and are being called now to fulfill that commitment by taking the collective action required to save the world’s coral reefs, and the lives and livelihoods they support. A request was also made to revise the official World Heritage policy on climate change. These are important first steps that will inspire our work as we forge a way forward in months and years ahead toward securing a better future for our common heritage of humankind.

© The Ocean Agency, XL Catlin Seaview Survey, Richard Vevers and Christophe Bailhache

You can download the full report, “Impacts of Climate Change on World Heritage Coral Reefs: A First Global Scientific Assessment,” here, and read about the Committee proceedings here. Many thanks to my co-authors Scott Heron and Mark Eakin NOAA Coral Reef Watch , as well as contributing authors Kristen Anderson, Jon C. Day, Erick Geiger, Ove Hoegh-Guldberg, Ruben van Hooidonk, Terry Hughes, Paul Marshall, and David Obura.

user_116639-370-390-20160803225929-1Dr. Fanny Douvere is the coordinator of the Marine Programme at UNESCO’s World Heritage Centre in Paris, France. Since October 2009, her mission is to ensure the 49 marine sites on UNESCO’s World Heritage List are conserved and sustainably managed so future generations can continue to enjoy them. She recently wrote in Nature on why not investing in marine World Heritage is a lost opportunity for the oceans.

Prior to her work at the World Heritage Centre, she co-initiated and led the Marine Spatial Planning (MSP) initative at UNESCO’s Intergovernmental Oceanographic Commission. In 2009 she co-published the UNESCO guide Marine Spatial Planning: A Step-by-Step Approach Toward Ecosystem-based Management. The guide has gained international recognition for setting a standard for the application of MSP and is available in six languages. She also served as an advisor to the United States Executive Office of the President (Council of Environmental Quality) on the development of the US Framework for Coastal and Marine Spatial Planning.

She co-authored more than 20 articles in internationally peer-reviewed journals on both marine World Heritage and MSP. Most recently, she authored for World Heritage Marine Sites Managing effectively the world’s most iconic Marine Protected Areas. A Best Practice Guide, in which she lays out a tangible approach for marine protected area management based on the fundamental idea that all things happen in time and space and the oceans should be managed accordingly.

Fanny obtained her PhD in 2010 from the Ghent University in Belgium and published the book Marine Spatial Planning: Concepts, current practice and linkages to other management approaches.

Connect with Fanny on Linkedin
Follow Fanny on Twitter


  1. Joseph Rangel
    July 27, 8:52 pm

    I have been connected with the formation of the first marine national park in the andamans,and presently trying to draw the attention to the barrier reef there covering approx29041 reported by Sewell in 1850s,am now retired and resident in brisbane australia

  2. Lyndon DeVantier
    July 21, 2:00 am

    This is a powerful warning of the likely short-term (decadal – century) future of our world’s coral reefs. including those exceedingly beautiful places inscribed on the World Heritage Register. I too have been fortunate to dive on many of these over the past 30 years. It is clear from this report, and indeed many others, that most reefs are already in serious decline from local – global impacts. When these declines are placed in the context of the ‘commitment’ we collectively have already made to continued warming for decades to come from fossil fuel emissions for energy and transport, deforestation and industrial agriculture, the situation is clearly dire. We have wasted much precious time – decades since the first IPCC report, in part because of the premeditated lies and untoward political meddling of powerful vested interests. This has to stop, yet many of these players continue their destructive dissembling. I sincerely wish Fanny and everyone else working to conserve reefs, and indeed our world’s heritage more generally, every success. Time is indeed short.

  3. Thomas Okey
    July 20, 11:46 am

    Hi Fanny,
    One tool that could enable participatory surveillance of reef conditions is the LEO Network at My goal is to implement LEO for the global oceans as ‘LEO Oceans’. Please check out the platform and let me know if you’d like to talk.
    Tom Okey