The world’s planners need to do more to prepare for a future where excessive temperatures will become a new norm in many areas of the world.

Summer 2023 was extremely warm, with everything from the El Niño global climate pattern to the massive eruption of an undersea volcano in the South Pacific, which spewed millions of tons of water vapor high into the atmosphere, being blamed for the extreme temperatures.

“But what we should be focusing on is the natural variability of the climate system,” said Ben Kirtman, a professor of atmospheric sciences at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science. “During the early to mid-2000s, there was a slowdown in global warming, and people tried to make the argument that climate change was over, that CO2 was not the problem.

“But then, it started to warm again,” Kirtman continued. “The fact is, Mother Nature doesn’t draw straight lines. There’s natural variability. We’re going to go through periods where the warming seems flat, and temperatures are not ratcheting up. And we’re going to go through periods where it really ratchets up, and that’s what we’re seeing now. This is a ratcheting up of the climate change signal. There’s a possibility that we’ll go through a period where it is going to slow down a bit, but it’s not going to reverse. This is going to be the new baseline.”

The evidence bears out Kirtman’s assertion. Last year was the Earth’s warmest on record, with the average global temperature for 2023 exceeding the preindustrial (1850–1900) average by 2.43 degrees Fahrenheit, according to scientists at the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information.

And those same researchers, as well as others, say there is a one-in-three chance that 2024 will be warmer than 2023, and a 99 percent chance that next year will rank among the top five warmest years ever.

The world’s biggest metropolises are bearing much of the brunt. Over the past three decades, rising temperatures in the 20 most populous capital cities experienced a 52 percent increase in the number of days reaching 95 degrees Fahrenheit, according to the London-based International Institute for Environment and Development.

But it’s not solely rising temperatures that are causing unbearable conditions.

“In the South, what’s turning out to be interesting scientifically but unpleasant for people is the humidity,” said Kirtman. “We didn’t anticipate that the humidity would go up quite as much as it has. There’s a lot more moisture in the atmosphere, and that’s making things unpleasant. And we understand why that is, especially in Florida. The oceans all around this peninsula are much warmer, and the warmer temperatures are putting more moisture into the atmosphere.”

However, when asked whether cities around the world doing enough to deal with a climate that’s getting increasingly warmer Kirtman’s response is “probably not.”

“We haven’t done enough to prepare for extended periods of excessive warming. We need to build smarter,” he explained. “Do we have enough cooling centres for our seniors? Are we doing enough for those folks who are living life on the edges and don’t have the financial resources to deal with the extreme heat? These are today problems, and we need to do more to make sure that people are safe.”

Building smarter means planting more trees, which remove Earth-warming carbon from the atmosphere; laying cooler pavement; and installing cooler bus stops and green roofs. “It’s basically, shade everywhere you can possibly put shade,” said Joanna Lombard, a professor in the School of Architecture and a founding member of the University’s Built Environment Behaviour and Health Research Group.

Lombard, who investigates the impacts of greenness and greening initiatives, also noted passive cooling strategies such as cooling a building without mechanical systems. “You bring in cooler air from the ground and then ventilate it through the ceiling. But that strategy works most effectively in northern regions,” she explained.

“How do we do mechanical intervention in a way that is not contributing to carbon emissions and is not killing people on their electric bills?”  Lombard said. “That’s the challenge that confronts us.”

Last year was the Earth’s warmest on record, with the average global temperature for 2023 exceeding the preindustrial (1850–1900) average by 2.43 degrees Fahrenheit, according to scientists at the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information.