Unusually, the current La Niña phenomenon has lasted for two winters and may even last until 2023. If that happens, it will be the third time since 1950 that La Niña has been so persistent.
“Overall, we tend to see more frequent La Niña events, and they tend to be more powerful. That’s actually the opposite of what most climate models say,” Klotzbach said. “There’s been a lot of discussion about whether this is some kind of natural variability.”
He noted that La Niña appears to have a variety of effects on weather, not just hurricanes. For example, it could exacerbate droughts in the American Southwest. Ultimately, a powerful combination of the effects of climate change and natural variability is hitting some parts of the world.
If there are indeed a lot of hurricanes in the Atlantic this year, no one knows how likely they are to actually make landfall, Pastelok said. But he added that he wants people to prepare for the worst, just in case: “With sea level rise, I think if one of those systems comes up on the east coast, the sea level is going to be crazy.”
However, the deadliest weather events in many parts of the world, including the US, are heat waves, said Frederic Otto, senior lecturer in climate science at the Grantham Institute for Climate Change and the Environment at Imperial College London.
And this year’s rare early heatwaves—for example, in India (with a record 49.2 degrees Celsius in May), France (with a record Earliest 40-degree day ever) and swathes of the U.S. — where 100 million people have been advised to stay indoors — — of particular concern, Otto said. “The health effects of early heatwaves are usually more severe than later in the summer, when our bodies have adapted.”
People should make sure they stay hydrated and avoid going out during the hottest part of the day, she suggested. If you can’t keep it cool enough at home, you might be able to use an air conditioner in a public building like a library. “It really takes heat seriously,” Otto said.
Clare Heaviside, a research fellow at UCL’s Institute of Environmental Design and Engineering, suggested that it may be time to reconsider architecture in places that used to be less accustomed to hot weather. Heatwaves in cities can be several degrees Celsius higher than in surrounding areas due to the urban heat island effect. This is sometimes exacerbated by air conditioning systems, which dissipate heat into the atmosphere while keeping indoor spaces cool, Heaviside said.
There are other ways to reduce the temperature inside a building, she said: “You can replace the roof with a more reflective roof, which will reduce the heat island temperature in the local city.” In a 2019 study, she and a Colleagues estimate that this could reduce deaths during heatwaves by 25 percent in urban heat island regions.
Even as anthropogenic climate change causes heatwaves to become more frequent, longer-lasting and more intense, there is still a lack of widespread awareness of extreme heat events in some countries, Otto said. “Many African countries do not have a definition of a heatwave, so if the temperature is abnormal, the weather service does not record or report it,” she noted.