Summers go on getting hotterand the consequences are impossible to miss: In the summer of 2023, the Northern Hemisphere has its hottest season in 2,000 years. Canada’s deadliest wildfires on record have engulfed skylines in smoke from Minnesota to New York. In Texas and Arizonahundreds of people lost their lives due to heat, and in Vermontflash floods caused damage equivalent to that of a hurricane.
Forecasts indicate that this year’s upcoming “danger season” has its own catastrophes in store. On May 23, scientists from the National Oceanic and Atmospheric Administration announced that the 2024 Atlantic hurricane season will most productive yet. A week earlier, they released a seasonal map predicting blistering temperatures over almost the whole country.
One driving force behind these projections is the alternating Pacific climate patterns known as El Niño and La Niña, which can cause large shifts in temperature and precipitation across the North and South American continents. After nearly a year of El Niño, La Niña is expected to take over sometime during the coming summer months. If climate change cook the planet and the Pacific shifts between these two cyclical forces, experts say the conditions could be ripe for more extreme weather events.
“We’ve always had this pattern of El Niño, La Niña. Now it’s happening on top of a warmer world,” said Zeke Hausfather, a climate scientist at Berkeley Earth, an environmental data science nonprofit. “We have to be ready for the type of extremes that have not been tested in the past.”
During an El Niño, changing trade winds cause a thick layer of warm surface water to form in the Pacific Ocean, which in turn transfers a large amount of heat to the atmosphere. La Niña, the opposite cycle, brings back cooler ocean water. But swinging between the two can also raise thermostats: Summers between the phases have higher than average temperatures. According to Hausfather, a single year of El Niño brings the same heat that about a decade of human-caused warming can permanently add to the planet. “I think it gives us a little taste of what’s to come,” he said.
Since the World Meteorological Organization declared the beginning of the current El Niño on July 4, 2023, it is almost a year in a row record temperatures. According to the National Centers for Environmental Information, there is a 61 percent chance that this year could be even hotter than last spells danger for areas prone to deadly heat waves during the summer months. an estimated 2,300 people in the US will die from heat-related illnesses in 2023, and researchers say the real number is probably higher.
All this heat also settled in the oceans, creating more than a year of creation super hot surface temperatures and more than half of the planet’s coral reefs are bleaching. It also provides potential fuel for hurricanes, which form when energy is sucked up vertically into the atmosphere. Normally, trade winds scatter heat and humidity across the water’s surface and prevent these forces from building up in one place. But during La Niña, cooler temperatures in the Pacific weaken high-altitude winds in the Atlantic that would normally break up storms, allowing hurricanes to form. easier form.
“When that pattern sets up in the Pacific, it changes wind patterns around the world,” said Matthew Rosencrans, a lead forecaster at NOAA’s Climate Prediction Center. “When it’s strong, it can be the dominant signal on the entire planet.”
This year’s forecast is especially dangerous, as a likely rapid midsummer transition to La Niña could combine with all that simmering ocean water. NOAA forecasters expect these conditions to spawn at least 17 storms large enough to be named, about half of which could be hurricanes. Even a hurricane with relatively low wind speeds can dump enough water to cause catastrophic flooding hundreds of kilometers inland.
“It’s important to think of climate change as making things worse,” said Texas A&M University climate scientist Andrew Dessler. While human-caused warming won’t directly increase the frequency of hurricanes, he said, it could make them more destructive. “It’s a question of how much worse it’s going to get,” he said.
Over the past 10 months, El Niño has helped create blistering temperatures in some parts of the United States, drying out the country. Drought-stricken areas are more vulnerable to severe flooding, as periods without precipitation mean rainfall is likely to be more intense when it finally arrives, and soils may be too dry to absorb water. As parched soil and rising temperatures dry out vegetation, the stage is set for wildfires.
While the National Interagency Fire Center expects a lower-than-average chance of a major fire in California this year, in part due to El Niño bringing unusually high rainfall to the state, other places may not be so lucky. The agency’s seasonal wildfire risk map emphasized Hawaiʻi, which suffered the country’s deadliest inferno partly due to a persistent drought in Maui last August. Canada, which also experienced its worst fire season last summer, could face more trouble after its warmest winter on record. In May, smoke was already billowing from hundreds of wildfires in Alberta and British Columbia seep across the Canadian border to Midwestern states.
“We’re leaving the climate of the 20th century, and we’re entering a new climate of the 21st century,” Dessler said. Unfortunately, our cities were built for a range of temperatures and weather conditions that no longer exist.
To prepare for hurricanes, Rosencrans said people living in states along the Gulf Coast and Atlantic Ocean should government disaster preparedness websites to find disaster kit checklists and advice on setting up an emergency plan. “Thinking about it now, rather than when the storm hits you, is going to save you a lot of time, energy and stress,” he said.
