16 percent of the U.S.'s coastline is at a "high hazard" risk due to rising sea levels and extreme weather and that number could double if various precautions are not taken, USA Today reported.

According to a new study by Stanford University scientists, sand dunes, coral reefs, sea grasses, mangroves and other natural habitats protect residents from extreme weather and, if not protected, would allow for worse damage and higher risk.

While many officials in coastal cities - the most vulnerable to hurricanes and harsh weather - have been investing in billion-dollar sea walls. The study suggests protecting the Earth's natural habitats would save cities a lot of money while still providing defenses to the elements.

"If we lose these defenses, we will either have to have massive investments in engineered defenses or risk greater damage to millions of people and billions in property," said lead author and Stanford scientist Katie Arkema in announcing the findings, published in the peer-reviewed journal Nature Climate Change.

To determine which areas are most protected and which are most vulnerable, the team developed a hazard index based on existence (or non-existence) of natural habitats, property value, population, sea rise and erosion.

The researchers found that 67 percent of the coastline is protected by natural habitats, but 16 percent of the coastline has high population totals and high property values. 1.3 million people and $300 billion in property value live within a kilometer of the shore areas deemed "high hazard" risk.

The study suggests that by the year 2100, due to climate changes and rising seas levels, the number of threatened people could be as high as 60 percent.

"This study is a pretty significant advance over what's been done before," says Virginia Matzek, a restoration ecologist at Santa Clara University in California. "If I were a county planner, I'd be all over this."

Peter Kareiva, chief scientist at The Nature Conservancy and one of the study's co-authors, said the government should invest in mapping coastal habitats instead of sea walls.

"We have the Human Genome. What about the Earth Genome?" he said, including habitats benefits such as recreation, fish nurseries, water filtration and erosion control. "It costs a ton of money to build a sea wall, and a sea wall does one thing only. Habitats do many."