Global heat wave shatters records. Will Wednesday break another?

When the heat spikes, humans suffer health effects — especially young and elderly people, who are vulnerable to heat even under normal conditions.

The planet’s temperature spiked on Tuesday to its hottest day in decades and likely centuries, and Wednesday could become the third straight day Earth unofficially marks a record-breaking high. It’s the latest in a series of climate-change extremes that alarm but don’t surprise scientists.

The globe’s average temperature reached 62.9 degrees Fahrenheit (17.18 degrees Celsius) on Tuesday, according to the University of Maine’s Climate Reanalyzer, a common tool based on satellite data, observations, and computer simulations and used by climate scientists for a glimpse of the world’s condition. On Monday, the average temperature was 62.6 degrees Fahrenheit (17.01 degrees Celsius), setting a record that lasted only 24 hours.

For scientists, it’s a sweaty case of I-told-you-so.

“A record like this is another piece of evidence for the now massively supported proposition that global warming is pushing us into a hotter future,” said Stanford University climate scientist Chris Field, who was not part of the calculations.

On Wednesday, 38 million Americans were under some kind of heat alert, said National Oceanic and Atmospheric Administration chief scientist Sarah Kapnick. She said the global heat is from a natural El Nino warming of the Pacific that heats up the planet as it changes worldwide weather on top of human-caused climate change from the burning of coal, oil and gas.

Even normally cooler communities are feeling the heat. In North Grenville, Ontario, the city turned ice-hockey rinks into cooling centers as temperatures Wednesday hit 90 degrees Fahrenheit (32 degrees Celsius), with humidity making it making it feel like 100.4 degrees (38 degrees Celsius).

“I feel like we live in a tropical country right now,” city spokeswoman Jill Sturdy said. “It just kind of hits you. The air is so thick.”

University of Maine climate scientist Sean Birkle, creator of the Climate Reanalyzer, said the daily figures are unofficial but a useful snapshot of what’s happening in a warming world. Think of it as the temperature of someone who’s ill, he said: It tells you something might be wrong, but you need longer-term records to work like a doctor’s exam for a complete picture.