With fewer particles clogging up the air, the sun-warmed ocean was the perfect conduit for strong storms, especially when paired with increasing greenhouse gas pollution, which traps heat in the atmosphere.
But although the study found that climate change played a role in shifting storms toward and away from certain spots on the planet, it didn't affect the overall number of storms that formed. However, the research showed that as the planet continues to heat up it could eventually lead to fewer hurricanes overall. But the ones that do form are more likely to be powerful Category 3, 4 and 5 hurricanes.
"In the future, we predict a decrease in tropical storms," Murakami said. Yet "we still predict increasingly strong tropical cyclones."
Climate change's role in forming storms remains complicated and not well understood. Scientists are careful not to make absolute statements like "climate change caused X hurricane," because that's not what the research shows.
Attribution science, as the field is known, is about discovering if climate change makes something more or less common. Murakami said that's simpler to do over a long period of time, like the 40 years analyzed in the study.
"Statistically speaking we can find some significant trends," he said. "But when you look at a specific tropical cyclone it's really difficult to figure out how climate change affected it."
Some connections, like hotter oceans fueling more powerful storms, are simple enough. As sea levels rise, hurricanes have more water to shove ashore, making storm surge higher and deadlier.
But as the air above the oceans warms, it actually makes the atmosphere more stable and complicates storm formation. That's why the NOAA study found that toward the end of the century the average annual number of tropical cyclones around the world could drop from 86 to 69.
And then there's the question of whether climate change will impact the number of El Ninos and La Ninas, weather systems that affect how and where hurricanes form around the globe.
"That's a big question too. There's no consensus there," Klotzbach said. "There's so many questions that need to be answered."
Hurricane season starts June 1, although a disturbance passing through the Florida Straits could strengthen into the first named storm of the season -- Arthur -- over the weekend.
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