Hurricane history

As I am writing, hurricane Harvey is still happening.  At the moment (the evening of August 27th, 2017) it seems poised to swing out into the Gulf, pick up energy, and swing back to deluge inland Texas again (as an aside, I saw someone on twitter claim that Hurricanes are powered by cold, therefore climate change is “not a thing.”  Hurricanes get their power from warm, moist air, often found over oceans.  NASA has a great primer on the mechanics of hurricanes here.)

I don’t want to take attention away from the rescue efforts that are taking place in Texas, but I did want to get some thoughts down about why hurricanes are simultaneously forecastable and unpredictable, and why that tension makes them a particularly fraught kind of disaster.

Hurricanes are easy to forecast.  They are large, and (mostly) easy to follow, predictable weather events.  The Galveston Hurricane (1900), which is in the running for deadliest recorded hurricane in American history was predicted by Cuban meteorologists (their prediction was ignored by American meteorologists).  Katrina (2005) was forecast.  Sandy (2012) (which resonates particularly with me, because I am from NJ and lived in NJ at the time) was forecast.  With some variation of strength and landing points, meteorologists know that hurricanes are coming, and where they will make landfall.

I think that for people who are unfamiliar with the Atlantic and Gulf seaboard, hurricanes feel like disaster-lite.  They are not tornadoes, which can appear, seemingly in seconds, and wreck damage that is so extreme that the most common comparison is a runaway freight train.  They are not earthquakes, which seem to strike capriciously.  They are not fires, which – often being caused by human negligence – are almost impossible to predict.  For people who do not live in hurricane country, hurricanes seem like easy disasters.  “Once you know they’re coming” – backseat disaster pundits say – “just get out of the way.”

Despite the confidence of forecasts, damage from hurricanes is incredibly difficult to predict.  Some  damage comes from storm surges (where the barometric pressure of the hurricane – basically, the weight of the water – physically pushes the ocean onto land).  This is what happened during Sandy, and during the Galveston hurricane.  Some damage comes with gale-force winds, which drive the sea onto and over coastal spaces.  Some hurricanes hit in places where natural defenses against flooding are insufficient.  Most spaces are at the intersection of these hazards. This is what happened during Katrina, and seems to be what is happening with Harvey.

This uncertainty is why one of the dominant themes in oral histories of Katrina is that, having survived previous hurricanes, many people of New Orleans thought that Katrina did not seem to pose that much of a risk.  If previous evacuation orders resulted in minimal damage, there was no incentive to leave.  However, the more significant predictor of failure to evacuate  is access to capital.  Evacuation requires a car.  It requires access to money to buy food.  It requires confidence that work will be cancelled the next day.  It requires a financial cushion that means that loosing material goods to looting can be recovered from.  Put pithily: people with social, political and economic capital can afford to evacuate; poor without, cannot.

This is why there are so many people pleading in Twitter for rescue.  This is why so  many people sheltered in place.  This is why so many people trusted government officials when they said that a few inches of water wasn’t dangerous.  This is why so many people where surprised when a few inches of water became a few, several, many feet.  Hurricane damage is unpredictable, and the people who are most subject to that unpredictability are the people who have least.

American hurricanes have a long history.  While individual storms seem capricious, in the last century and change, patterns have begun to emerge.  They are worth attending to as we face the midst, and aftermath, of the latest deadly storm.

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