Earth just hit a doozy of a milestone—its hottest day ever recorded. And it's just part of the latest scorching stretch this summer, as well as a distressing sign of what’s to come. From Mexico to China to the United States, heat records continue to be shattered, putting us in “uncharted territory,” in the words of Carlo Buontempo, who directs the European Union’s Copernicus Climate Change Service. Alarming, yes—though not the whole big picture. As Bob Deans, NRDC’s director of strategic engagement, put it in a recent interview on WGN Radio: “These are the hallmarks of global climate change,” but we can still do something. Here’s what you should know.

So what does the “hottest day on earth” mean?

We’ve heard July 6 became the hottest-ever day in modern recorded history, hitting a global average of 63.01 degrees Fahrenheit, according to data from the U.S. National Centers for Environmental Prediction. What that actually means is a little more nuanced. This new record is still considered unofficial, but it’s a reliable estimate based on averages of temperatures measured by weather stations all around the world. And if a new global record temperature of 63.01 degrees Fahrenheit doesn’t sound so bad, just remember that it takes into account temperatures from the Arctic, Antarctic, and other frozen places. Also, these direct observations of global temperatures date back only to 1979, but scientists have recently suggested this is likely the warmest period in more than 120,000 years.

And that’s the more worrying bit. July 6 was the final in a string of four scorching days in a row to either break or tie the global heat record—making it one of the hottest weeks of the hottest years of the hottest decades in human history.

What is this a symptom of?

The primary culprit is unchecked climate change. A sharp increase in greenhouse gases in our atmosphere, mostly from the rampant burning of fossil fuels, has caused the planet to warm by roughly 2 degrees Fahrenheit since the preindustrial era, leading to increasingly hot summers. (The return of El Niño, a cyclical weather pattern that impacts temperature and precipitation, is also likely playing a role this year.)

In the same week as the earth’s hottest day, a new report came out estimating that more than 60,000 people died from Europe’s unprecedented heat wave last summer. Beyond this being a clear public health emergency, soaring temperatures can also cause other reverberating challenges, from electricity grid failures to damaged agricultural crops to worse wildfire seasons.

But the die isn’t cast. Every action taken—and every fraction of a degree of warming we prevent—matters. “What we’re talking about is the difference between catastrophic warming that overwhelms our capacity to deal with it versus warming that we can deal with,” Bob told WGN.

What actions can we take?

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