Hurricanes' Intensity, Frequency Impacted By Climate Change: NOAA

FLORIDA — Although hurricane season doesn't officially begin until June 1, the National Hurricane Center said it's seeing more tropical storms form in the Atlantic in May, and this year is no exception.

The hurricane center is keeping a close watch on a subtropical storm that could form off the East Coast next week and move southwest along the Eastern Seaboard. If it forms, it will be the first named storm of the season.

Ken Graham, director of the National Hurricane Center in Miami, said the storm is not expected to be severe but that it should serve as a reminder this week to residents to begin stocking up on supplies and making evacuation plans as the country observes National Hurricane Preparedness Week.

The Atlantic hurricane season officially runs from June 1 to Nov. 30, but named storms have formed prior to the official start of the hurricane season in about half of the past 10-15 years, including each of the past seven years from 2015 to 2021, Graham said.

Pending the outcome of a technical study by the U.S. National Weather Service, the World Meteorological Organization's hurricane committee is now considering moving up the official date for the start of hurricane season.

"We had more category 4 and category 5 landfalls in the U.S. from 2017 to 2021 than from 1963 to 2016," Graham said. "Hurricanes don’t care about international boundaries. We need to be prepared."

He said March demonstrated the planet's continuing warming trend. It ranked as the fifth-warmest March in 143 years, according to scientists from NOAA’s National Centers for Environmental Information.

March 2022 was also the 46th consecutive March and the 447th consecutive month with temperatures above the 20th century average.

Since hurricanes form over relatively warm sea surfaces, Graham said it's reasonable to conclude that global warming will greatly increase hurricane activity around the world.

Evaporation intensifies as temperatures rise, and so does the transfer of heat from the oceans to the air. As the storms travel across warm oceans, they pull in more water vapor and heat. That means stronger winds, heavier rainfall and more flooding when the storms hit land.

Weather forecasters depend on two factors to develop statistical analyses and models for the upcoming hurricane season: local tropical sea surface temperatures (SSTs) and the Power Dissipation Index (PDI), a measure of past Atlantic hurricane activity combining frequency, intensity and duration of hurricanes.

Both Atlantic SSTs and the PDI have risen sharply since the 1970s. There is some evidence that PDI levels in recent years are higher than in the previous active Atlantic hurricane era in the 1950s and '60s.

"If this statistical relation between tropical Atlantic SSTs and hurricane activity is used to infer future changes in Atlantic hurricane activity, the implications are sobering," Graham said. "The large increases in tropical Atlantic SSTs projected for the late 21st century would imply very substantial increases in hurricane destructive potential — roughly a 300 percent increase," Graham said.

Agreeing with that assessment is Evan Thompson, president of the World Meteorological Organization's Regional Association for North America, Central American and the Caribbean.

He cited the recently released Sixth Assessment Report by the WMO's Intergovernmental Panel on Climate Change. It concluded "the global proportion of tropical cyclones that reach very intense (Category 4 and 5) levels, along with their peak winds and rainfall rates, are expected to increase with climate warming," he said. "Developing countries and small islands are on the front lines. Accurate early warnings are no longer a luxury, but a must."

Higher sea temperatures are exacerbated by rising sea levels caused by melting glaciers.

The average global sea level has already risen by half a foot since 1900 — nearly 4 of those inches since 1970 — as countries have developed and populations have grown.

Higher sea levels push more water inland during hurricane-related storm surges, resulting in more destruction.

Additionally, warmer climates produce stronger hurricanes, Thompson said.

Researchers say the most damaging U.S. hurricanes are three times more frequent than 100 years ago, and the proportion of major hurricanes (Category 3 or above) in the Atlantic Ocean has doubled since 1980.

This all means that both local government and residents must plan ahead to protect life and property, Graham said.

NOAA Administrator Dr. Rick Spinrad said the WMO's Sixth Assessment Report leaves no doubt that policies of governments and the behavior of people have caused climate warming resulting in more destructive hurricanes.

"We must urgently reduce our emissions while also increasing our efforts to adapt to the impacts we can no longer avoid," Spinrad said. "Simply put, societies and ecosystems need to prepare now for the increasing effects of extreme heat, drought, sea level rise and other impacts of climate change."

He urged governments to heed these warnings.

"It’s our goal to engage even more elected officials and business leaders in using NOAA’s data, products and services so that they can create climate plans of their own," he said. "As NOAA’s administrator, it is my goal to ensure that our agency is helping these decision makers build a climate-ready nation that strengthens our resilience to climate change, which will help protect lives, lifestyles and livelihoods."

The National Hurricane Center has provided a series of documents in both English and Spanish to help residents prepare:

• Determine Your Risk
• Develop An Evacuation Plan
• Assemble Disaster Supplies
• Get An Insurance Checkup
• Strengthen Your Home
• Help Your Neighbor
• Complete A Written Plan

See related stories:

• 2022 Hurricane Names List Released For Atlantic Season
• Above-Normal 2021 Atlantic Hurricane Season Predicted By NOAA