Rising Sea Levels Threaten Coastal Cities Worldwide: New Data Reveals Alarming Projections and Urges Action
By 2050, projections show that hundreds of highly populated coastal cities will be exposed to increased flood risk due to sea level rise caused by global warming. This includes land home to roughly 5 percent of the population of coastal cities such as Santos, Brazil, Cotonou, Benin, and Kolkata, India. By 2100, on our current emissions pathway, this exposure is expected to double to land occupied by 10 percent of the population in these highly populated coastal areas.
The impacts of this increased flood risk on coastal regions, which are often sites for major social and economic hubs, could potentially trigger reversals in human development worldwide. The extent of coastal flooding has already increased over the past 20 years, with 14 million more people worldwide now living in coastal communities with a 1-in-20 annual chance of flooding.
New hyperlocal data released by Human Climate Horizons, a collaboration between the United Nations Development Programme (UNDP) and the Climate Impact Lab (CIL), maps in detail this fivefold increase in susceptibility to flood damage along the world’s densely populated coastlines. This data platform provides information on where sea-level rise impacts may most threaten homes and infrastructure.
Many low-lying regions along the coasts of Latin America, Africa, and Southeast Asia may face a severe threat of permanent inundation, potentially leading to a reversal in human development in coastal communities worldwide. By 2100, climate change is expected to cause the submergence of a significant share of land in Small Island Developing States (SIDS) and Associate Members of United Nations Regional Commissions.
At the highest levels of global warming, approximately 160,000 square kilometers of coastal land could be inundated by 2100, compared to a future with no climate change. This includes vast stretches of coastal cities in Ecuador, India, Saudi Arabia, Vietnam, and the United Arab Emirates. However, with concerted action to reduce global emissions and limit warming below 2 degrees Celsius, a significant portion of at-risk land is projected to remain above sea level.
Pedro Conceição, Director of UNDP’s Human Development Report Office, emphasizes the importance of taking action now to address the effects of rising sea levels on densely populated coastal zones. Without shoreline defenses, several cities are projected to fall permanently below sea level by the end of the century, including Guayaquil, Ecuador, Barranquilla, Colombia, Santos and Rio de Janeiro in Brazil, Kingston in Jamaica, Cotonou in Benin, Kolkata in India, and several cities in Australia.
The data provided by Human Climate Horizons empowers global citizens and decision-makers with localized information on the projected impacts of climate change on people and communities. The platform unveils projections of local sea-level rise and its impacts under different emissions scenarios, derived from satellite and tidal gauge observations and model ensembles from the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report.
Hannah Hess, associate director at the Climate Impact Lab, highlights that these projections can serve as a catalyst for action. Swift and sustained action to reduce emissions can mitigate the risks faced by coastal communities and provide more time to proactively respond and prepare for rising seas.
In addition to sea-level rise impacts, the platform also illustrates how climate change is projected to influence temperature and its impacts on mortality, energy use, and the global workforce. These projections are available for 24,000 regions worldwide, shedding light on the implications of unmitigated climate change and highlighting areas where the risks are most severe.
The key findings of the data show that without shoreline defenses, several countries and territories are projected to be permanently inundated by the end of the century under different emissions scenarios. The number of people living in areas with a 1-in-20 annual flood risk is also expected to increase significantly by 2100.
The release of this data serves as a reminder to decision-makers attending COP28 that urgent action is needed to address the impacts of climate change on coastal communities. The time to act is now to prevent further irreversible damage to our planet and its inhabitants.