African Heritage Sites threatened by coastal flooding and erosion as sea-level rise accelerates

Abstract

Important heritage sites along the African coast are at risk from the threats associated with rising sea levels. Here, we quantify the exposure of natural and cultural heritage sites in Africa to coastal flooding and erosion in the 21st century. We develop a comprehensive database of 284 coastal African Heritage Sites (AHS), composed of 213 natural and 71 cultural heritage sites, which is then combined with coastal flooding and erosion projections to assess exposure to coastal extreme events for a moderate (RCP4.5) and high (RCP8.5) greenhouse gas emissions scenario. We find that 56 AHS are presently at risk from a 100-year extreme sea-level event, with a total exposed heritage area of 2,222 km2. Most of the currently exposed AHS are located in Northern and Western Africa. By mid-century, the number of exposed AHS is projected to increase more than 3 times to reach 191 and 198 under moderate and high emissions respectively. In the second half of the century, the number of exposed sites stabilizes, but the median exposed area increases to 6.6 to 8.5 times the present-day value, under moderate and high emissions, respectively. Mitigation from high to moderate emissions will reduce the end-century median exposed area and number of very highly exposed sites by 20% and 25% respectively.