NASA analysis shows irreversible sea level rise in Pacific islands as climate change rapidly changes a region of the world home to millions of people. Over the next 30 years, Pacific island nations such as Tuvalu, Kiribati and Fiji will see sea levels rise by at least 6 inches (15 centimeters), according to an analysis by NASA’s Sea Level Change Science Group. That level of rise would occur regardless of whether greenhouse gas emissions change in the coming years.
The Sea Level Change Study Group conducted the analysis of the region at the request of several Pacific island countries, including Tuvalu and Kiribati, and in close cooperation with the US State Department.
In addition to the overall analysis, the agency’s sea level team produced high-resolution maps showing which areas of various Pacific island nations will be vulnerable to tidal flooding, also known as nuisance flooding or sunny day flooding, by the 2050s. Published on September 23, 2024, the maps outline the flooding potential under different emissions scenarios, from best-case to routine to worst-case.
“Sea levels will continue to rise for centuries, causing more frequent flooding,” said Nadia Vinogradova Schiffer, who manages ocean physics programs in NASA’s Earth Science Division. “NASA’s new flood tool shows what potential increases in flood frequency and severity could look like in the coming decades for coastal communities in Pacific island nations.”
The team, led by researchers at the University of Hawaii and collaborating with scientists at the University of Colorado and Virginia Tech, began with flood maps for Kiribati, Tuvalu, Fiji, Nauru, and Niue. They plan to create high-resolution maps for other Pacific island nations in the near future. The maps could help Pacific island nations decide where to focus mitigation efforts.
“Science and data can help the Tuvaluan community communicate accurate sea level rise projections,” said Grace Mali, a youth leader from Tuvalu who is involved in the Rising Nations Initiative, a U.N.-backed program led by Pacific island nations to help preserve their nationhood and protect the rights and heritage of people affected by climate change. “It will also help with early warning systems, which is what our country is focusing on right now.”
Pacific island nations like Kiribati, a low-lying country in the South Pacific, are now preparing for a future of higher sea levels. NASA Earth Observatory
The Sea Level Change Group’s analysis also found that the number of days with tidal flooding on average per year will increase by an order of magnitude for nearly all Pacific island nations by the 2050s. Parts of the NASA group’s analysis were included in a report on sea level rise published by the United Nations in August 2024.
Areas of Tuvalu that currently experience fewer than five high-tide days per year will average 25 flood days per year by the 2050s. Areas of Kiribati that currently experience fewer than five flood days per year will average 65 flood days per year by the 2050s.
“I live in the reality of climate change,” Mali said. “Everyone in Tuvalu lives on the coast or along the coastline, so everyone is affected greatly by this.”
Flooding on island nations can occur when the ocean inundates land during storms or exceptionally high tides, called king tides. But it can also happen when saltwater seeps underground and pushes the water table to the surface. “There are places on the island where we will see seawater bubbling up from beneath the surface and causing severe flooding,” Mali added.
Sea level rise does not occur uniformly across the globe. A combination of global and local conditions, such as coastline topography and the distribution of glacial meltwater in the ocean, influences the amount of rise a particular region will experience.
“We always pay special attention to the differences in sea level rise in different regions, but in the Pacific Ocean the numbers are surprisingly consistent,” said Ben Hamlington, a sea level researcher at NASA’s Jet Propulsion Laboratory in Southern California and the leader of the agency’s sea level change science team.
The impacts of a 6-inch (15-centimeter) sea level rise will vary from country to country. For example, some countries may experience nuisance flooding at their airports several times a year, while others may experience frequent flooding in areas equivalent to nearly half the year.
The researchers would like to combine satellite data on sea levels with ground-based measurements of sea level at specific locations, as well as more accurate information on land elevation. “But these countries really lack ground-based data,” Hamlington said. Combining space and ground-based measurements could provide more accurate predictions of sea level rise and a better understanding of the impacts on countries in the Pacific.
“The future of Tuvalu’s young people is already at risk,” Mali said. “Climate change is more than an environmental crisis. It is about justice, the survival of countries like Tuvalu, and global responsibility.”
