By 2100, the human population is expected to shoot up to 11 billion people.

At the same time, the world’s landmass will shrink as rising sea levels swallow coastlines, displacing an estimated 2 billion people from their homes, according to a new analysis from Cornell University.

The world is already struggling to cope with the largest displaced persons crisis in history, 65.6 million people, and a crisis that’s orders of magnitude bigger will present radically different challenges.

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Most immediately, countries will have to find a way to accommodate those displaced as they flock inward on remaining land mass and determine how to provide enough food, water, and other necessities when resources are strained by the other effects of climate change — droughts, storms, extreme precipitation, and so on.

“We’re going to have more people on less land and sooner that we think,” said lead author Charles Geisler, professor emeritus of development sociology at Cornell, in a statement. “The future rise in global mean sea level probably won’t be gradual. Yet few policy makers are taking stock of the significant barriers to entry that coastal climate refugees, like other refugees, will encounter when they migrate to higher ground.”

Read More: How a Tiny Alaska Town Is Leading the Way on Climate Change

By 2060, the authors estimate that 1.4 billion people will be displaced, more than four times the prediction of an earlier report.

This change reflects the growing understanding of climate change and its acceleration. A recent analysis found that sea level rise increased by 50% since 1993. Further, there are signs that natural buffers against climate change are reaching their breaking points. While carbon emissions stayed flat in the past three years, the amount of carbon in the atmosphere surged, meaning that less carbon is being soaked up by the oceans and forests. 

All around the world, coastal places are dealing with the escalating dangers of climate change.

Read More: Your Doctor Might Start Warning You About Climate Change — Here’s Why

In Miami, politicians across the political spectrum have begun preparing for a mass exodus.

The Maldives, a small string of Pacific islands, is building new islands for people to relocate to when existing islands get submerged at tremendous expense.  

In Palau, another small Pacific island, the government created the largest marine reserve in the world to serve two purposes: create a large buffer against waves and attract global investment for inevitable relocation.

In coastal Bangladesh, rising sea levels, landslides, erosion, and cyclones are causing saltwater to seep into rivers, ruining vast sections of rice fields and rendering water undrinkable.

Read More: Is Climate Change Really a ‘National Security Threat?’

In Mexico City, the ground is sinking as the city’s aquifers get depleted from overuse, drought, overdevelopment, and warming temperatures.

The city of Guangzhou, a multi-trillion dollar powerhouse in China, is being inundated by rising waters and extreme precipitation. In 2016, the city experienced the most rainfall in history and the sewage systems of the poorer and more crowded neighborhoods are already becoming wrecked.

The authors of the report warn that humanity’s many vulnerabilities will be exposed as these problems intensify and it could force reconceptions of borders, human rights, global aid, and more.  

“The pressure is on us to contain greenhouse gas emissions at present levels,” he said. “It’s the best ‘future proofing’ against climate change, sea level rise and the catastrophic consequences likely to play out on coasts, as well as inland in the future.”


Defend the Planet

There Could Be 2 Billion Climate Change Refugees by 2100

By Joe McCarthy