African World Heritage sites threatened by rising seas



The largest population of giant tortoises in the world thrives on a group of East African islands in the Indian Ocean. The tortoises of Aldabra Atoll in the Seychelles sit at the top of the food chain, an unusual feat for a herbivore.

A continent away, waters wash the shores of Kunta Kinteh Island in the Gambia River, a historic outpost of the West African slave trade that later housed a fort to stop slave ships. The island recalls both the practice and the abolition of slavery.

The giant tortoises of Aldabra Atoll in the Seychelles graze on grasses and shrubs, where plants have evolved to meet their needs. Credit: UNESCO/Ron Van Oers, CC BY-SA 3.0 IGO

Aldabra Atoll and Kunta Kinteh Island are both UNESCO World Heritage Sites, and both are at increasing risk of extreme coastal flooding from rising sea levels. D By 2100, 37% of Aldabra Atoll and 46% of Kunta Kinteh Island will be at risk of extreme flooding and erosion if no policies are adopted to stop emissions, new research shows.

These two sites are not alone. Twenty percent of World Heritage sites in Africa are now vulnerable to rising seas. And by 2050, that percentage will more than triple if emissions are not reduced. The projection comes from an international team of scientists who mapped nearly 300 heritage sites along the African coast. The scientists published their results in Natural climate change.

African countries were responsible for less than 4% of global carbon dioxide emissions in 2020.

The latest discovery is another example of countries contributing little to climate change and suffering disproportionately from its consequences. African countries were responsible for less than 4% of global carbon dioxide emissions in 2020. The average person in Nigeria or Mali is responsible for the same amount of carbon dioxide emissions each year as an Australian or American in just over 2 days. Yet rising sea levels will exacerbate flooding and coastal erosion on valuable cultural and natural sites along the continent’s 300,000 kilometers of coastline.

Nigerian climate activist Oladosu Adenike Recount Carbon Panties this lost heritage could mean “erasing our history”.

“In Africa, our natural and cultural heritage defines us – it tells our story and can trace our history. Once lost, it cannot be replaced or restored.

“Outstanding Universal Value”

Heritage sites are recognized as having ‘outstanding universal value’ and represent important sites for culture, history and science. The island of Kunta Kinteh, for example, is “an important but painful memory for many African countries”, said Nick Simpson, a climatologist at the University of Cape Town in South Africa and co-author of the new research. There are more than a thousand World Heritage sites around the world, and the latest analysis includes both official sites and those awaiting approval.

The study reveals that sea level rise is endangering both natural sites, such as the iSimangaliso wetlands in South Africa (home to leopards, hippos and elephants), and sites cultural sites, such as the ruins of the ancient trading post of Tipasa, Algeria, and the great sea of ​​Egypt. fortress, the Citadel of Qaitbay.

The study focuses on extreme events that occur rarely but are enhanced by higher sea levels. “What is a year in 100 [flood] event in 2010, which is our baseline, will change significantly with each decade to come,” Simpson said.

Eight African countries will be particularly affected: Cameroon, Republic of Congo, Djibouti, Libya, Mauritania, Mozambique, Namibia and Western Sahara.

Mozambique is the most exposed country by area, with 5,600 kilometers of coastline threatened by 2050 under a moderate emissions scenario.

“Each of their heritage sites will have some measure of exposure to extreme sea levels,” Simpson said. The study considered scenarios of global warming that represent moderate emissions that peak at 2040 before declining, called RCP (Representative Concentration Pathway) 4.5, and high emissions that continue without policy intervention, called RCP 8.5. In both cases, all the sites of the eight countries will be threatened.

Mozambique is the most exposed country by area, with 5,600 kilometers of coastline threatened by 2050 under a moderate emissions scenario.

Natural heritage sites contain the most land, and by 2100, with moderate emissions, sea levels will jeopardize a cumulative area of ​​15,000 square kilometers, roughly the size of Connecticut.

The study is “of particular interest to the African scientific and policy community for effective long-term planning solutions”, said Grégoire Abessolo Ondoa of the University of Douala in Cameroon. Ondoa served as reviewer on the published article.

Rethinking climate change and heritage

Climate change is jeopardizing other World Heritage sites, including the Great Barrier Reef in Australia, the Monarch Butterfly Biosphere Reserve in Mexico and Garajonay National Park in Spain. Climate change is the biggest danger for sites in general, according to a 2020 World Heritage report. In the Mediterranean, 37 out of 49 low-lying coastal cultural sites are threatened by rising sea levels, according to a Nature Communication 2018 paper.

Climate change adaptation and mitigation are linked to heritage, risk and our relationship to place.

Marcy Rockman, archaeologist and member of social protection group Co-Equal, said the new study shows how climate change adaptation and mitigation are linked to heritage, risk and our relationship to place.

Geophysical instrumentation researcher Errol Wiles of the South African Institute for Aquatic Biodiversity, who reviewed the paper, criticized the research.

“Considering sea level rise as purely anthropogenic is not appropriate,” he said. Comparing the effects of human-caused sea level rise with “natural” sea level rise would strengthen the work, Wiles said.

“I agree that heritage sites are already at risk under current conditions, as shown by our baseline simulations from 2010,” said Lena Reimann, a water and climate risk specialist at the Vrije Universiteit Amsterdam, who participated in the study. “Without accounting for sea level rise, we find that 56 sites (20% of heritage sites) are threatened by a 100-year coastal extreme event.”

—Jenessa Duncombe (@jrdscience), personal writer

Quote: Duncombe, J. (2022), African World Heritage Sites Threatened by Rising Seas, Eos, 103, https://doi.org/10.1029/2022EO220097. Published February 24, 2022.
Text © 2022. AGU. CC BY-NC-ND 3.0
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