Sea level rise observed since 1970 is responsible for 43% of homes impacted by Hurricane Irma’s storm surge.   Sea level rise since 1970 also caused an additional 57,000 homes to be impacted by Irma according to a study by First Street Foundation, a non-profit in the US.

Hurricane Irma’s storm surge impacted over 133,000 homes across Florida, causing extensive flooding and damage. The research used a geospatial analysis to model the impact of an Irma-like storm at the sea levels observed in 1970 and found that 57,000 of the properties impacted last year would not have been affected with 1970 sea levels – signaling that the rise in sea level was responsible for these additional impacts.

The study also found that if Hurricane Irma were to hit at the sea level projected for 2050 by the Army Corps of Engineers, approximately 0.4m above current levels, the storm surge would affect an additional 200,000 homes. In other words, a .04m increase in nearby sea levels alone would result in a 150% increase in the number of homes impacted by Hurricane Irma’s storm surge.

Higher sea levels cause greater storm surge, as there is more water available for storms to push onto land, and that additional water removes friction that would otherwise slow the surge.

Research has shown that sea level rise has a non-linear positive impact on storm surge; the conservative models used in this research show that increases in sea level rise result in an additional 23% relative increase in storm surge.

Small increases in sea levels are causing and will cause disproportionate increases to the reach of storm surge.