A new evaluation of coastal elevation suggests that at least three times more people are at risk from rising sea levels than previously believed.
Previous research has indicated that around 80 million people would be affected by annual flooding of coastal areas. New research from US NGO Climate Central has deployed artificial intelligence and eliminated the effect of tall buildings and tree canopies that were previously included in satellite data. The new estimate suggests that about 300 million people will be affected, with the worst impact felt in low-lying cities in Asia. Many are key economic centers such as Mumbai, Ho Chi Minh City, Bangkok and Shanghai. The effect of rising seas has already been felt in Indonesia where the country's may be moved from Jakarta to a more climate resilient location.
Climate Central suggests that more sea defences may offer temporary relief, but that it is difficult to estimate the extent of necessary protection. Standard projections are based on an assumption that greenhouse emissions (a key contributor to climate change) are cut in line with the promises of the Paris Agreement on climate change. But these promises are falling behind schedule and may not even be met. The United States has withdrawn from the agreement, setting an awkward example for the remaining parties.
Rising sea levels will also be affected by expected greater instability of the Antarctic ice sheet. The report suggests that up to 640 million would be affected by the end of the century.
The research did not update the annual economic impact of rising sea levels. The World Bank’s estimate of $1 Trillion USD per year by mid-century estimate may be understated, given the scale of upward adjustment in population affected.
Sea-level rises may induce large-scale migration away from unprotected coastlines, redistributing population density and putting great pressure on inland cities. Historically, large-scale migration poses serious challenges to political stability and possibly contributing to conflict.
The report suggests that further research on global-scale modeling of the timing, locations, and intensity of migratory responses to increased coastal flooding is urgently needed to minimize the potential human harm caused by such threats.