A new study published in Science Advances Wednesday has bad news for the residents of low-lying atolls: If current greenhouse gas emission rates continue, climate change will render most of these islands uninhabitable by mid-century, not by the end of the century as previously believed.

This could turn the more than half a million people who live on atolls into climate refugees, The Guardian reported Wednesday.

The dramatic difference between these and previous findings is because previous studies only looked at sea level rise.

However, this study, conducted by the U.S. Geological Survey (USGS), Deltares, National Oceanic and Atmospheric Administration and the University of Hawaiʻi at Mānoa, also looked at the impact of flooding from "wave overwash" when waves from storms wash over the islands. The scientists found that this flooding would pose a serious threat to the islands' supply of fresh drinking water, rendering it non-potable between 2030 and 2060 and forcing residents to leave.

"The tipping point when potable groundwater on the majority of atoll islands will be unavailable is projected to be reached no later than the middle of the 21st century," lead author and USGS geologist Curt Storlazzi said in a USGS press release.

Overwash flooding will also impact infrastructure and wildlife habitats, but the danger it poses to drinking water is especially severe.

"The overwash events generally result in salty ocean water seeping into the ground and contaminating the freshwater aquifer. Rainfall later in the year is not enough to flush out the saltwater and refresh the island's water supply before the next year's storms arrive repeating the overwash events," USGS hydrologist and study author Stephen Gingerich explained in the release.

For this study, the researchers looked at Roi-Namur Island on Kwajalein Atoll in the Republic of the Marshall Islands. However, they said their findings would apply to atolls worldwide, which have similar shapes and lower average elevations. These include the more than 1,100 low-lying islands on 29 atolls in the Marshall Islands and atolls in the Caroline Islands, Cook Islands, Gilbert Islands, Line Islands, Society Islands, Spratly Islands, Maldives, Seychelles and Northwestern Hawaiian Islands. Most atolls are located in the Indian and Pacific Oceans.

A study published Tuesday found that climate change had not been the driving force behind the past 50 years of forced displacement in East Africa.

But the atoll study is one of many that points to a looming crisis of global displacement that will come sooner than expected if the world doesn't act quickly to reduce emissions and curb climate change.

"Millions of people are going to be at risk from extreme heat, extreme water shortages and flooding as well as sea level rises ... we are talking about something that is going to play a huge role in the years ahead in terms of forcing people to leave their homes," Dina Ionesco of the International Organization for Migration told The Guardian.