What is a super typhoon and why is it so dangerous?

This was a record week for global hurricanes as powerful storms hit both the Pacific and Atlantic Ocean basins, leaving scientists wondering if they are harbingers of a more destructive climate-warmed future or if they are outliers that put limits to the test, but they remain within the realm of normal variability.

On Sunday, the Super Typhoon Goni left a trail of destruction over several smaller Philippine islands, with winds estimated at 195mph. It was the strongest storm to ever hit land, according to measurements from the National Oceanic and Atmospheric Administration’s National Hurricane Center and the Navy’s Joint Typhoon Warning Center. Fortunately, Gomi lacked densely populated Manila and its environs. It is expected to hit Vietnam with heavy rains and minor winds late Thursday evening.

And in the Caribbean, hurricane category 4 Eta hit the Nicaraguan coast on Tuesday in 240km / h winds, causing “life-threatening swells, catastrophic winds, flash floods and landslides” across parts of Central America, according to a Tuesday morning notice from the NOAA Hurricane Center. Nicaragua’s emergency officials have issued an evacuation order for the entire coast and the region is expected to be inundated with up to 35 inches of rain by Sunday.

Hurricane Eta is the 28th named storm of 2020 in the Atlantic Basin, hitting the record set in 2005.

The reason both storms were so strong and so delayed is that both the Pacific and Atlantic oceans remained warm this year, says John Knaff, a meteorologist at Colorado’s Cooperative Institute for Research in the Atmosphere. NOAA State University. “The Atlantic season is a prototype of what happens when you have very warm sea surface temperatures,” says Knaff. “You have more energy for storms to get very strong.”

Meteorologically, typhoons and hurricanes are the same phenomenon; it is only tradition to call them typhoons in the western Pacific or hurricanes in the eastern Pacific or the Atlantic. They start as storms that pass over the surface warm water, at least 80 degrees Fahrenheit, up to 150 feet deep. These storms draw water from the ocean surface, which evaporates into the air. As they rise, the water vapor condenses to form droplets, releasing more energy, while the low pressure underneath the rising air masses brings a discharge of more air. A tropical storm officially turns into a hurricane when these counterclockwise winds reach 74 miles per hour. Meteorologists applied the “super” designation to Typhoon Goni after reaching wind speeds of 150 miles per hour.

Earlier this year, NOAA officials predicted that 26 named hurricanes, three to six classified as “major,” would form in the Atlantic, and academic research teams separately predicted a hurricane season. ” hyperactive “. So far in 2020, five of the 28 storms have been severe. “I was skeptical at the start of the season in the Atlantic,” says Knaff. “But it was pretty spectacular.”

In contrast, NOAA forecasters predicted a slower-than-normal storm season in the Pacific, and although Super Typhoon Goni was large, that forecast generally proved correct.

Knaff is an observational meteorologist who studies the environmental conditions that give rise to hurricanes. Others, like Kerry Emanuel, are studying how climate change is driving the formation of major storms like Goni and Eta, and how that could change in the future as air and ocean temperatures continue to rise. “What’s interesting is that we’ve been breaking all kinds of records in general over the past decade,” says Emanuel, a professor of atmospheric science at the Massachusetts Institute of Technology.

Globally, seven of the 10 strongest storms that have taken place on land have occurred since 2006, according to NOAA’s Historic Hurricane Trace Database (IBTrACS). It is based on federal documents dating back to the 1930s. Prior to Typhoon Goni, 20 Category 5 super typhoons with winds of at least 160 mph have hit the Philippines since 1952. It’s almost as if the speed limit is removed during major storms, Emanuel says.

Researchers are getting better at fine-tuning global climate models that predict the weather patterns we will see as atmospheric carbon dioxide levels continue to rise and Earth approaches the two degrees Celsius of warming predicted by mid-century. In fact, a recent report from the United Nations World Meteorological Organization states that the planet’s vital signs have just been slowed by the economic freeze of the pandemic and that the world is on track to see the five warmest years on record. Warmer air temperatures mean the atmosphere holds more water vapor from the oceans, water vapor that turns into rain from hurricanes. At the same time, storms draw more heat energy from warm surface waters to fuel their development – the warmer the water, the stronger the storm.