How Things Work: Powerful hurricanes are powered by warmer seas and climate change
Hurricane Harvey inundated much of Houston in several inches of water in a matter of days. This week, Hur- ricane Irma’s 185 mph winds are devastating the Caribbean and heading for Florida next. We’re right in the grips of hurricane season, so it seems like there’s a storm every other week. In fact, there are two others forming in the Gulf of Mexico right now: Hurricanes José and Katia.
I found myself asking what exactly causes such power- ful storms, and why they occur at this time of the year, every year. I wonder if these storms are getting stronger and more disastrous with time (Irma is the strongest recorded hurricane), and if climate change is to blame. Is such a quick succession of storms normal, or are we see- ing something that has never happened before? Some of these questions have de nite answers, and the others are more ambiguous, so let’s begin from the top.
A hurricane is a rapidly rotating storm system with a low pressure center (called an eye). These storms are characterized by heavy rain and strong winds. Hurricanes are always born over oceans in tropic regions. They can range in diameter from 100 km to 2,000 km (about the width of Brazil), packing more energy than several nuclear bombs combined.
Large bodies of warm water cause hurricanes, acting as their energy source; the tropical regions of the Atlantic and Pacific oceans are most opportune. Angular momentum imparted by the Earth’s rotation, along with ocean currents and temperature changes along latitudes and longitudes drive the swirling winds. All three of these factors are needed to sustain strong storm systems, which is why hurricanes quickly dissipate upon landfall.
So many other factors affect hurricane formation. For example, the southern hemisphere experiences fewer hurricanes because of its high rates of vertical wind shear and low number of oceanic jets.
I've always thought hurricanes have interesting names: Katrina, Ike, Harvey. It turns out these aren’t randomly selected, or the names of the meteorologists who first spot the storm forming (a false claim I believed for years). They're names chosen from a register controlled by the World Meteorological Organization (WMO), which meets annually to discuss the storms of the season and retire hurricane names. If more than 21 storms strike in a season, names are then chosen from the Greek alphabet.
Hurricanes aren’t all doom and gloom. They disrupt harmful weather patterns, preventing susceptible areas from prolonged droughts. They also carry thermal energy away from the tropical regions and distribute it to the higher altitudes, helping to regulate global climates.
What I want to know is if the 2017 hurricane season is unusual. I don’t ever recall seeing such strong hurricanes strike in such quick succession. Moreover, scientists have always warned that severe climate change will exacerbate natural disasters. Is that what we’re witnessing right now?
Firstly, it turns out 2007 saw the greatest number of hurricanes in a single year, so 2017 has competition. Secondly, scientists and news outlets have concluded that unusually warm oceans gave Hurricane Irma its record-breaking strength. Hovering over waters at 29 degrees, Irma has access to leagues of energy.
Interestingly, hurricanes aren’t unique to Earth’s atmosphere. The most well known extraterrestrial storm is the Great Red Spot, found on Jupiter. This swirling cloud of red gas is larger in diameter than the Earth itself, and is essentially perpetual; it has been observed continually for 187 years (since 1830). The high pressure zone below Jupiter’s equator is ample for forming what’s called an anticyclone.
Hurricanes are a natural consequence of classic physical principles like conservation of energy and angular momentum. Even though they deliver unimaginable damage and destruction to coastal populations, hurricanes also regulate the atmosphere and dissipate energy concentrated at the equator.
Perhaps, the most unfortunate aspect of hurricanes is that they devastate regions that do not greatly contribute to global warming. The Caribbean islands and coastal towns, for example, will bare the brunt of even more powerful storms in the future, as large industrial nations like China, India, Russia, and the United States continue to pump large amounts of carbon dioxide into the atmosphere.
There is no quick fix. Agreements like the Paris Accord might not do enough or act fast enough. Until we change our relationship with energy and fossil fuels, natural distaters will only increase in strength and category.