An extremely worrisome climate model predicts, based on current global warming projections, that storm surges - the most damaging and dangerous part of a hurricane - are set to increase in frequency and magnitude by as much as ten times by the turn of the century due to climate change. The scientists involved in the study warn that based on their findings, we're already starting to pay our dues for XXth century warming as storm surges the size of Katrina are now at least twice as common as they were a century ago.
Storm surges are deadly and devastating walls of water that roar ashore during hurricanes. It was storm surges that caused most of the $125 billion in damage and killed 1,800 people when Katrina hit. Last year, Sandy storm surges killed dozens of people and caused roughly $50 billion in damage.
Climate scientist Aslak Grinsted of the University of Copenhagen in Denmark, along with colleagues, analyzed storm surge records from six tide gauges along the southeast coast of the US, which extend back to 1923. These were used in conjunction with modern, high-detail observations to perform a statistical projection of how powerful and frequent these storms might be in the future, both on average and extremes.
Bigger and meaner hurricanes
The researchers conclude that there will be tenfold increase in frequency of storm surges if the climate becomes 3.6 degrees Fahrenheit warmer - a Katrina magnitude surge every other year. Current global warming scenarios have mean temperature rise anywhere from 2.0 to 5.2 degrees by the end of the century. The main driver for hurricanes is warm water , and coupled with rising sea levels, things aren't looking too bright for coastal residents.
While these predictions are extremely worrisome (can the US handle a Katrina every other year or so? I don't think so...), it's important to note that even to this day hurricanes are poorly understood. Moreover, the data sets the researchers gathered and analyzed from the the turn of the last century are minimal and poor in details compared to current modern day satellite observations, and as such do not provide a reliable foothold. Sure, they're alright for estimating and correlating, given we don't have anything better at hand, still reality might differ from their predictions.
Is the study flawed? Maybe, but here's something worth considering: when the researchers looked in the past, not in the future, they had something locked in right - “we have probably crossed the threshold where Katrina magnitude hurricane surges are more likely caused by global warming than not,” the researchers note. To be more precise, Katrinas are twice as likely to happen that a mere century ago.
The study was published in the journal Proceedings of the National Academy of Sciences.