Extreme coastal floods, once rare, are now becoming more common due to climate change fueled by human activities, new research reveals. This study highlights the importance of planning for floods and infrastructure in coastal areas as the planet warms.

Coastal floods occur when high tides and storm surges combine with rising sea levels. This is further complicated by natural climate patterns and human influences. Scientists indicate that climate change intensifies storms like Hurricane Ian, which led to major flooding in 2022. Flooding affects hundreds of millions in low-lying coastal regions worldwide, leading to billions in damages and potential loss of life.

Floods with a historical 1% chance yearly on coastlines are now 12 times more likely, according to a study published in Nature Climate Change. Human-driven climate change has made these events four times more frequent. Researchers analyzed extreme sea level events through tide gauge records from over 100 sites and climate models. Their study spans from 1900 to 2005, as post-2005 data lacks models pointing to human-driven climate change impacts. The findings may understate current risks since human contributions to climate extremes have increased since then.

The research examined changes caused by human activities, natural forces, or landscape shifts. Before the 1960s, natural forces mainly influenced sea level changes. Since then, however, human-induced warming has become the primary factor. Another report in Science Advances aligns with these findings, noting climate-change-induced extreme ocean heights account for about 58% of significant floods from 2000 to 2018. It also shows a near tripling of days reaching extreme flood levels since the 1970s. “Essentially every coastal flood today has human fingerprints on it through climate change,” said Ben Strauss, chief scientist at Climate Central.

The study in Nature Climate Change did not fully explore each human factor. Lead author Sönke Dangendorf noted greenhouse gases from fossil fuel burning remain dominant since the 1970s, urging that communities should prepare for escalating threats.

Retired U.S. Geological Survey oceanographer Jeff Williams, though not involved in this research, emphasized the need for planners to consider increasing risks and funding for coastal protection.

Citing New Orleans’ current protections as inadequate beyond the next few decades, Williams indicated the urgency for action. Several nations are adopting renewable energy sources like solar and wind. In the last year, renewable energy’s share in global electricity surpassed one-third for the first time, despite increased U.S. fossil fuel usage under previous administrations. Scientists believe the world is deviating from worst-case warming scenarios but still not achieving optimal ones.

“Even small sea level rises impact our coasts considerably,” said Dangendorf from Tulane University, adding, “There is hope because we control emissions to some extent.”