That was A record week for global hurricanes, with violent storms hit both the Pacific and Atlantic basins. Scientists wondered whether they are harbingers of a more destructive, climate-warming future or outliers testing the limits – but staying within the realm – of normal variability.
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On Sunday, super typhoon Goni left a trail of destruction over several smaller Philippine islands, whose winds were estimated to be 195 miles per hour. 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 missed densely populated Manila and its surroundings. Vietnam is expected to hit late Thursday with heavy rainfall and less wind.
And in the Caribbean, Category 4 Hurricane Eta hit the coast of Nicaragua on Tuesday at 145 mph winds, leading to "life-threatening storm surges, catastrophic winds, flash floods and landslides" in parts of Central America Tuesday morning consultation by the Hurricane Center, according to a consultation the NOAA. Nicaraguan emergency officers issued an evacuation order for the entire coast and the region is expected to be doused in up to 35 inches of rain by Sunday.
Hurricane Eta is the 28th named storm of 2020 in the Atlantic Basin and builds on the record of 2005.
The reason both storms were so strong and so late is because both the Pacific and Atlantic have stayed warm this year, says John Knaff, a meteorologist at the NOAA Cooperative Institute for Atmospheric Research at Colorado State University. "The Atlantic season is a prototype for what happens when the sea surface temperatures are very warm," says Knaff. "You have more energy to make the storms very strong."
Typhoons and hurricanes are meteorologically the same phenomenon; It is just traditional to call them typhoons in the western Pacific or hurricanes in the eastern Pacific or Atlantic. They start out as storms that go over hot surface water of at least 80 degrees Fahrenheit to a depth of 150 feet. These storms suck up water from the ocean's surface that evaporates into the air. As they rise, the water vapor condenses to form droplets and releases more energy, while a lower pressure below the rising air masses draws in more air. A tropical storm officially turns into a hurricane when those counterclockwise winds reach 74 miles per hour. Meteorologists applied the term "super" to Typhoon Goni after it hit winds of 150 miles per hour.
Earlier this year, NOAA officials predicted 26 named hurricanes would form in the Atlantic, three to six of which were rated "major", and academic research teams separately predicted a "hyperactive" hurricane season. So far in 2020 five of the 28 storms have been severe. "I was skeptical at the beginning of the season in the Atlantic," says Knaff. "But it was pretty spectacular."
In contrast, NOAA forecasters predicted a storm season in the Pacific that was slower than normal, and although super typhoon Goni was a big one, that forecast has generally proven correct.
Knaff is an observational meteorologist who studies the environmental conditions that lead to hurricanes. Others, like Kerry Emanuel, are studying how climate change is driving large storms like Goni and Eta, and how this may change in the future if both air and sea temperatures continue to rise. "The interesting thing is that in the last decade we've been shaking all kinds of records in general," says Emanuel, professor of atmospheric science at the Massachusetts Institute of Technology.
According to the NOAA Historical Hurricane Trace Database (IBTrACS), seven of the ten strongest storms that have landed worldwide have occurred since 2006. This is based on federal records from the 1930s. Before typhoon Goni, 20 category 5 super typhoons with wind speeds of at least 250 km / h had struck the Philippines since 1952. It's almost like the speed limit is lifted in a big storm, says Emanuel.
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Researchers can better optimize the global climate models that predict the weather patterns we'll see as atmospheric carbon dioxide levels continue to rise and the earth approaches the two degrees Celsius warming expected by mid-century. A recent report by the United Nations World Meteorological Organization states that the planet's vital functions have been barely slowed by the economic freeze from the pandemic and that the world is on track to see the warmest five years in existence. At warmer air temperatures, the atmosphere holds more water vapor from the oceans, water vapor that turns into rains from hurricanes. At the same time, storms draw more thermal energy from warm surface waters to fuel their development – the hotter the water, the stronger the storm.