A new study is the first to put a dollar figure on the effect of global warming in the 2012 superstorm.
When Hurricane Sandy slammed the East Coast in 2012, the storm sent an extra 9 feet of water over and above New York harbor’s high tide gauges, flooding tunnels and streets, causing widespread power outages, and leaving in its wake economic damage of roughly $60 billion. A new study has combined flood-damage modeling with climate models to find that $8 billion of those damages are the fault of human-caused sea level rise.
Scientists have become increasingly adept over the last decade at teasing out the influence of climate change on both the likelihood and the severity of specific weather events. The authors of this latest paper, published Tuesday in the journal Climate Communications, said their analysis is the first to measure the cost differential between a climate changed world and not.
The research implies that “there’s been a climate change price tag on pretty much every coastal flood in the world for the last half century,” said Ben Strauss, a lead author of the study and chief executive officer of Climate Central, a non-profit that disseminates climate science. “But we simply haven’t done the accounting.”
The study’s authors used an advanced hydrological model to estimate the extent of flooding from Sandy using sea-level heights from tidal gauges in 2012; they then calculated the flooding that would have occurred if tides were at their 1900 levels, about 4 inches lower than in 2012. Using the Federal Emergency Management Agency’s flood models, they arrived at a figure for what damages would have been in the absence of climate change.
Those 4 inches of sea-level rise, according to their analysis, had a disproportionately high impact on the price tag of the storm. Strauss said the elevated tide not only made floodwaters spread more broadly, it also deepened flooding in affected areas. As big bodies of water rise during storms, human developments channel them into narrower spaces, forcing water levels up. An extra inch or two of sea level can mean tens of thousands of dollars of additional damage per structure.
The $8 billion is a minimum estimate, the authors said. They focused solely on how human-caused sea rise affected the storm, but other factors associated with climate change such as warmer ocean temperatures also likely effected the size and intensity of the storm.
Michael F. Wehner, a senior scientist in the Computational Research Division at the Lawrence Berkeley National Laboratory, said he thought similar modeling would work for other storms, but that adjustments would need to be made. Wehner himself is working on a paper about Hurricane Harvey, which hit Texas in 2017 and caused roughly $90 billion in damage. His paper, which has been accepted by the journal Climatic Change, estimates that human-caused warming added $13 billion to Harvey’s bottom line.
Wehner points out that unlike Sandy, where most of the damage was from storm surge, most of the flooding in Harvey was caused from rain. In other storms, damage is caused predominately by wind, or some combination of wind and water. “I am confident that such climate change increases to hurricane economics can be quantified on a storm-by-storm basis,” he said