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Remnants of Hurricane Ida walloped New York, New Jersey and parts of Pennsylvania this week, leaving many homeowners in this densely packed population hub in snarled commutes and water-logged basements into late week.
At least 46 people drowned in their homes or cars and the National Weather Service for the first time triggered a “flash flood emergency” warning across New York’s boroughs. Politicians called for funding a subway upgrade as transit riders found themselves again hip deep in flood water.
Philadelphia was not spared either. Multiple tornadoes and road-closing downpours hit that region and predictions call for the most robust river flooding in a decade on Thursday and Friday.
In other words, even if you’re out of the eye of the storm, you can get wet. Powerful storms increasingly are blown deeper inland and carry more rain.
Like 2012’s Hurricane Sandy which hit the U.S. Northeast, Hurricane Ida packs fresh lessons for how the U.S. must take precautions against climate change’s more-immediate impacts. That’s even as the nation works toward renewable energy growth, carbon emissions capture and other means of slowing global warming.
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Coastal areas, including Miami, and in the Gulf of Mexico, Tampa and New Orleans, where Ida unloaded the bulk of its wrath on the 16-year anniversary of 2005’s Hurricane Katrina, have long been considered the front lines as hurricane seasons break records.
That’s still true. But the science behind why climate change is heightening weather events, including inland impacts, has grown sharply in recent decades. That science is complex, nuanced and still evolving. It also should not be ignored, say climate-change experts.
As policymakers, investors and homeowners come to terms with the changing world, a little science to pull out of the back pocket can help make sense of why greater action is needed.
Here’s the basic science, and some steps to better prepare.
1. Hotter temperatures kick up more water. Weather (short term) and climate (longer term) are two different factors. Confusing weather with climate has long been fuel for climate-change deniers. Where the two intersect is what matters. Studies show that warming air and ocean temperatures are increasing the odds and severity of heavy precipitation events. That leads to changes in hurricanes that are making them more powerful and potentially more damaging.
Specifically, for every 1°C (1.8°F) increase in temperatures, the atmosphere can hold 7% more moisture.
As the storms travel across warm oceans, they pull in more water vapor and heat. That means stronger wind, heavier rainfall and more flooding when the storms hit land.
In New York, for instance, all-time rainfall records were shattered Wednesday. The city replaced a milestone it set just over a week ago with 3.15 inches of rain in one hour in Central Park.
More rain is expected if Earth is allowed to warm further. Studies project a 10%-15% average increase in rainfall rates of tropical storms in a 2°C global warming scenario, according to the site Climate Central, which teams up journalists and scientists.
2. There are just more hurricanes, period. Last year wrapped with a record 30 named hurricanes and 2021 has been predicted to be another strong year. Forecasters at the National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center see a 60% chance of an above-normal 2021 season, which typically should end in November.
3. Greater freqency, greater damage. A report from the U.N.’s World Meteorological Organization this week said global weather disasters tied to climate change strike four to five times more often and create seven times more damage than in the 1970s.
The report also showed that weather disasters are killing far fewer people since the 1970s and 1980s as preventative measures, including flood walls and evacuation plans for those who can afford them, are more common.
It is, however, costing the country more to weather them out. That’s because expanding development has occured in at-risk areas. As such, Ida is expected to top Katrina’s nearly $164 billion in economic losses, U.N. officials predicted, though said the impact was still being added up.
4. Calendar change? The World Meteorological Organization (WMO) and the National Hurricane Center are considering advancing the start date of hurricane season to May 15. And earlier awareness could bring better preparation.
While the storm itensity data has accumulated, it’s not yet clear that climate change is causing tropical systems to occur earlier. So for now the experts are waiting on redefining the June-November hurricane season. The pause is a solid example of reverence for the evolving nature of science in this area.
5. Hurricane homework. For residents and business owners in hurricane paths, and even those just outside the typical reach of the storms, a better understanding of flood risk and insurance needs is one way to prepare for these intensifying seasons.
FEMA collects information on flood insurance for each state and you can check out NOAA’s interactive billion-dollar weather and climate disasters website to find historic events near you.
Using FEMA data, the Natural Resources Defense Council has created an online tool to find repeatedly flooded properties in each state and county, along with National Flood Insurance Program claims.
Pew Charitable Trusts has compiled research on local flood mitigation efforts around the country, and the National Conference of State Legislatures collects resources on state-level actions on flood issues.
