This week researchers published a study investigating the extinction of the world’s final surviving wooly mammoths on St. Paul Island in the Bering Strait. While their kind disappeared in Europe and Siberia around 10,000 years ago, this small population of giants lived peacefully for nearly 5000 years more. It wasn’t hunters or predators or even disease that wiped out the last of the wooly mammoth; it was thirst.
The last wooly mammoths, a thirsty species on a small island, ran out of water. Today humans are facing down the barrel of the same gun on small islands like Kiribati, Tuvalu and the Solomons and low-lying peninsulas like south Florida and Bangladesh.
The problem is saltwater intrusion, the penetration of groundwater aquifers by seawater. There are two major factors leading to saltwater intrusion (also called a saltwater wedge), sea level rise and the over-extraction of groundwater for human and agricultural use. More dense than freshwater, as saltwater enters these underground aquifers, it pushes the freshwater to the top. As people continue to draw water from the aquifer, the freshwater is slowly replaced from the bottom up by undrinkable, agriculturally destructive saltwater. Eventually, the aquifer is rendered useless.
This is exactly what happened to the last surviving wooly mammoths. As sea levels rose alongside a warming climate that melted glaciers in frozen waters, the freshwater table was inundated by saltwater. Over time, the freshwater available on the island could no longer sustain these fuzzy beasts and, just like that, they disappeared.
Several catastrophic events will accompany sea level rise. Just this week, the National Oceanic and Atmospheric Administration released a study of coastal real estate that suggests that by the end of the century nearly 1.9 million homes in hundreds of cities around the U.S. will be underwater, costing the economy almost a trillion dollars. But it’s likely coastal homeowners will be gone by the time their houses are flooded. Freshwater underground aquifers will be inundated by saltwater long before neighborhoods are. Without water our infrastructure falls apart – sanitation, food production, the power grid, they all depend on unlimited access to freshwater.
Don’t worry, the U.S. will be fine. We have plenty of land well above sea level and federal funds are already being allocated to help in the relocation of communities under threat from sea level rise. The Biloxi-Chitimicha-Choctaw tribe earned the dubious distinction of being the first community to receive assistance to move their community from their rapidly shrinking homeland, the Isle of Jean Charles off the Gulf Coast of Louisiana, to higher ground.
The tiny island nations of the South Pacific are not so lucky. With little land all at sea level, they simply have nowhere to move. The president of Kiribati, an island republic of just over 100,000 people is already in talks to move its entire population to 5,000 acres in Fiji. Most of Kiribati’s people have already moved from among its 32 low-lying atolls to a single island, Tarawam. The villages they left behind are being slowly washed away.
Things aren’t much better elsewhere. The Maldives and Tuvalu are under threat of extinction. Five islands belonging to the Solomon Island archipelago have already been reclaimed by the sea; six others have reluctantly given up large swaths of land. And though there are other islands to move to in the archipelago, these aren’t safe in the long term either, with sea levels expected to rise at least five feet by 2100.
Just like in the U.S., though, most communities will be uninhabitable by the time the ocean actually reclaims the land; saltwater intrusion will render their water unusable. No water, no life.
It’s unlikely that the populations of these islands will end up with nowhere to turn when their survival becomes impossible. But what happens to them then? They’ll become just another community of refugees with no homeland. They’ll survive, yes, but they won’t live well.