For decades, global warming was seen as something for our grandchildren to worry about. But with heat records tumbling relentlessly, it’s clear tomorrow has arrived. We are the hapless grandchildren. And it’s also clear we’re not ready for the heat.

Monday was the hottest day in recorded history, with the average global temperature hitting 62.87 degrees, according to the Copernicus Climate Change Service. That smashed the previous record set way back on, uh, Sunday.

Before Sunday, the previous record was set in July 2023. In fact, the past 10 years have had the 10 highest annual maximum temperatures on record, according to data dating to 1940. The highs of the past two years shifted into a new gear, crossing 62.6 degrees for the first time. Last year, we could chalk some of that heat up to El Niño. But El Niño has ended, and the mercury is alarmingly high.

These are the highest highs in roughly 125,000 years. As climate change deniers never tire of pointing out, the climate always has been changing. That hot period 5,000 generations ago — when temperatures might have maxed out at 2.7 degrees above preindustrial averages — was followed by an ice age. After that, the planet warmed to the pleasant temperatures in which human civilization thrived for 240 generations.

The bad news: Those pleasant temperatures are a thing of the past. We’re on track to zoom past 2.7 degrees of warming on the way to something closer to 5 degrees. These may be the hottest years in recorded history, but they’re also some of the coolest we’ll ever enjoy again.

Higher temperatures turbocharge the planet’s weather engines, leading to more frequent and severe heat waves, droughts, wildfires, floods, storms and hurricanes. Temperatures eventually will melt ice sheets and raise global sea levels, eradicate the Amazon rainforest, unleash methane gas and ancient pathogens, kill coral reefs and switch off the Atlantic Ocean current that controls Europe’s thermostat. There will be mass migration and resource wars.

The deadliest immediate effect is the heat itself. It attacks human health on every level. The problem is so big and so insidious we don’t yet grasp its full scope.

The more than 2,300 heat-related deaths in the U.S. last year were only those in which heat was an obvious contributor. A 2020 study suggests the true number could be more than twice as high. Uncounted global heat deaths could approach half a million yearly.

Quantifying heat’s threat to health is crucial, but we also need to be better educated about its dangers. That includes changing a cultural attitude toward heat as “something that should be willingly embraced, bravely endured, blithely ignored, or in the case of some marginalized communities, entirely deserved,” Vox’s Umair Irfan and Aja Romano wrote.

To their last point, the people most vulnerable to heat are the elderly, small children, people with underlying ailments and those without air conditioning.

Millions of Americans who work outdoors lack relief from the heat. In Florida and Texas it’s illegal for local governments to require companies give employees regular shade and water breaks. The Occupational Safety and Health Administration could save lives by imposing nationwide standards, but it has only just begun a yearslong rulemaking process.

Even OSHA’s proposal, which drew virulent Republican backlash, will leave 7.9 million public workers unprotected. That’s because the law establishing OSHA only gives it authority over private companies. Public workers must rely on states for protection, and 23 of them haven’t bothered. Along with the Federal Emergency Management Agency’s reluctance to consider heat waves natural disasters, these are oversights Congress needs to fix.

If Earth’s atmosphere suddenly included a colorless, odorless gas that never went away and killed and sickened millions each year, we’d consider that a public-health emergency on the scale of a pandemic. We should treat the permanent new state of global heat with the greatest urgency.

Prior to becoming a columnist, Mark Gongloff worked for Fortune.com, the Huffington Post and the Wall Street Journal.