Earth has quite a number of natural disasters, from earthquakes to storms to floods. Every year, many countries are visited by these hazards. One of the most feared are hurricanes, which are considered the most violent storms on Earth. The Atlantic hurricane season, a period when hurricanes usually form in the Atlantic Ocean, is expected to bring above-average activity from the tropics this year. Amid the coronavirus pandemic, researchers warn of this season, which can be more harmful than ever.
The Atlantic Hurricane Season
The Atlantic hurricane season, which usually begins June 1 and ends November 30, is fueled by just two ingredients: heat and water. As the hot air rises above the ocean’s surface, it leaves a lower pressure region below it. This process repeats as air from higher pressure areas move into the lower pressure area, heats up, and rises. As a result, it will produce swirls in the air and eventually cools off and condenses into clouds as the hot air gets high enough into the atmosphere. The growing, swirling vortex of air and clouds would only grow more and can become a thunderstorm.
"When the waters are warmer, it tends to mean you have lower pressures. It means a more unstable atmosphere, which is conducive to hurricanes intensifying. These thunderstorms, which are the building blocks of hurricanes, are better able to organize and get going,” Phil Klotzbach, an atmospheric scientist at Colorado State University, said.
According to Live Science, a science news website that features groundbreaking developments in science, space, technology, health, the environment, our culture, and history, scientists analyze several factors to predict how many storms the season will bring such as wind speed and sea surface temperatures. The Climate Prediction Center classifies hurricane seasons in three types: below-normal (between four and nine tropical storms and two to four hurricanes); near-normal (between 10 and 15 tropical storms and between four and nine hurricanes), and above-normal (between 12 and 28 tropical storms and between seven and 15 hurricanes).
While the Atlantic hurricane season starts on June 1, the peak is typically September. During mid-August to mid-October, we can see over 74% of tropical storm days, 87% of category 1-2 hurricane days, and over 95% of category 3-5 (major) hurricane days. The warm waters in the Atlantic Ocean play a huge role to condition the hurricanes. Wind shear or the change in wind direction with height into the atmosphere is also another factor.
"When you have a warm tropical Atlantic, you have reduced levels of wind shear. When you have a lot of wind shear it o basically tears apart the hurricane,” Klotzbach said.
A ‘Very Active’ 2020 Atlantic Hurricane Season
Scientists from the Colorado State University (CSU) recently predicted that the 2020 Atlantic hurricane season to be more active than usual. The team forecasts a total of 16 named storms, eight hurricanes and four major hurricanes. This is above the 30-year average of 12 named storms, six hurricanes and three major hurricanes. "We anticipate that the 2020 Atlantic Basin hurricane season will have above-normal activity," Klotzbach said.
According to CNN, an American news-based pay television channel owned by AT&T's WarnerMedia, four of the hurricanes will become major storms of Category 3 to 5 with sustained winds of at least 111 mph. The scientists said that the chance that at least one major hurricane will make landfall this year along the US coastline is 69%, up from an average of 52% over the last century. Also, there’s a 95% chance that at least one hurricane this year will make landfall in the country.
"The last season with four or more major hurricanes was the record damage-causing year of 2017 that saw Hurricanes Harvey, Irma, and Maria. All caused significant damage in the US and Caribbean,” CNN meteorologist Brandon Miller said.
The researchers also forecast more major hurricanes than is typical per year: four as opposed to the average of 2.7. The Accumulated Cyclone Energy (ACE), a collective measure of overall activity in terms of number, intensity, and longevity of storms, is predicted to be 140% of the long-term average. Findings reveal that tropical systems are intensifying more rapidly and likely slowing down their forward motion due to the warming temperatures. These can result in stronger winds, heavier rain, and flooding.
"There are only so many resources that we can marshal to mitigate these crises as they become increasingly more frequent and widespread. We'll be forced into a very troubling triage environment where all we can hope for is to limit the damage, death, and destruction,” Prof. Michael Mann, director of the Earth System Science Center at Pennsylvania State University, said.
One of the reasons behind the above-normal Atlantic hurricane season this year is La Niña. According to Science News, an online site that features daily news articles, feature stories, reviews, and more in all disciplines of science, it is a cyclical phenomenon that brings cooler waters to the tropical Pacific Ocean and changes wind patterns over the Atlantic in ways that can help strengthen hurricanes. La Niña can also enhance rising motion over the Atlantic Basin, making it easier for storms to develop.
La Niña has always been associated with a more active hurricane season. The La Niña years of 2010 and 2011 are among several tied for the third-most-active Atlantic seasons on record. Meanwhile, a lack of El Niño conditions is also expected to make things worse. When El Niño Southern Oscillation (ENSO), a natural cycle found in the Equatorial Pacific waters, is in its warm El Niño phase, it can disrupt tropical systems, which can tear them apart. Unfortunately, this summer and fall, an El Niño wasn’t forecasted.
The researchers are also looking into how warm the Atlantic, Caribbean, and Gulf of Mexico are. According to Weather.com, an online site that provides local and national weather forecasts, an above-average number of tropical storms and hurricanes will more likely form if temperatures in the main development region (MDR) between Africa and the Caribbean Sea are warmer than average. Mann said that year-to-year variability is now bolstered by warmer ocean waters due to global heating.
"Bottom line, human-caused warming is leading to increasingly intense tropical cyclones in the Atlantic and other basins,” he said.