If sea levels continue to rise around the world at their current pace, then coastal flooding will double in the decades ahead, according to new research.

Many of the world’s most bustling cities will be especially vulnerable to this increase, which could jeopardize the global economic order and put tens of millions of lives at risk.

A team of scientists recently studied the extent of this risk and where the danger is most acute. They published their findings in the Scientific Reports journal.

The team found, essentially, that the entire world is at risk, but that certain areas will experience a sharp increase in flooding within the decade, while other areas will see this shift over the next few decades.

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Countries in lower altitudes as diverse as Brazil, the Philippines, and the Ivory Coast will be affected first, while countries in Europe and North America will experience a delay.

Eventually, however, nearly every coastal region will see the frequency of floods double. And the researchers stress that this is an open-ended, cumulative prediction — how rapidly sea levels will rise over the next several decades is unknown but it could be much higher than currently estimated.

“It is pretty much inevitable that we are going to see increased frequency of extreme water levels,” Sean Vitousek, at the University of Illinois at Chicago, who led the research, told The Guardian. “There is no way around this.”

To get a sense of how the problem could keep multiplying, it’s useful to look at sea level rise predictions over the past several years.

In 2013, the UN estimated that sea levels will rise between 30 cm and 100 cm by 2100. In 2016, research published in Nature said that sea level rise will more likely be between 200 cm and 300 cm.

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At the heart of this uncertainty is the nature of the ice caps. These miles-deep, miles long structures have never melted in modern history and scientists are worried that their dissipation could accelerate as environmental feedback loops become more pronounced — ice reflects sunlight, water absorbs sunlight, so the more an ice cap melt, the more heat is absorbed by surrounding water and the faster it could melt, and so on.

The most extreme prediction of sea level rise is upwards of 260 feet.

But it wouldn’t take such a catastrophic increase to cause catastrophic damage around the world.

In 2014, 8.3 million people around the world were displaced from their homes and lives by flooding. If flooding doubles in population dense areas around the world, displacement could grow exponentially.

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Other forms of environmental displacement are on the rise, as well. The proportion of environmental displacement from extreme storms, for example, has nearly doubled in recent years.

By 2100, as many as 13 million people living in coastal regions of the US and hundreds of millions more people throughout the world could be displaced by climate change.

This displacement, while the most costly, is just one consequence of climate change — infrastructure will also be ruined, agriculture disrupted, and water sources compromised.

Economies, meanwhile, will be seriously harmed by these environmental shifts, compounding all the other problems.

Cities are already scrambling to cope with rising sea levels and more frequent flooding by building adaptable infrastructure, sea walls, and drainage systems. These systems can buy time, but they’re not permanent fixes and can eventually be overwhelmed.

The only permanent fix to this dilemma is to stop contributing to climate change.