Summers are always hot. Here's how we know climate change is making summer 2023 hotter.

Summers are always hot. But this summer is different in some profound ways.

Record-breaking temperatures are hitting multiple cities. Phoenix recorded an unprecedented nineteen consecutive days over 110 degrees. Death Valley reached 128 on Sunday. Records are falling everywhere.

It's not your imagination: This is not a typical summer.

The extreme temperatures being recorded this summer are the result of the combination of natural variations within the climate system and human-caused climate change, with a hefty serving of El Niño thrown in.

Here's what to know:

How do we know climate change is fueling this heat? Couldn't it be just a hot summer?

Natural variability still exists, said Daniel Swain, a climate scientist a the University of California, Los Angeles.

“But we’re starting to see the long-term, human-caused warming signal overwhelming that volatility. At this point, there aren’t any unprecedentedly extreme heat events on Earth that haven’t been exacerbated by climate change.”

The good news: He doesn't believe Earth has reached some sort of climate tipping point and there's no hope.

This does not appear to be a sudden, sustained acceleration of the long-term trends climate scientists have been noting for decades.

"I know a lot of people are freaking out right now," he said.

"This year we’re stair-stepping upward due to human-caused climate change," Swain said. "The more we warm, the easier it becomes to hit previously inconceivable levels of heat."

It actually is that hot:

Here's a few global signs that the heat the United States is experiencing this summer is something much more significant than just a heat wave.

• June was the hottest ever in NOAA's climate record: Earth's average global temperature in June was 1.89 degrees above average, making it the hottest June in the 174-years global climate record. It also marked the 47th-consecutive June and the 532nd-consecutive month with temperatures above the 20th-century average, according to the National Atmospheric and Oceanographic Administration.
• The past seven years have been the Earth's hottest: The years between 2015 and 2021 were Earth's warmest on record "by a clear margin," according to research by the Copernicus Climate Change Service, a group affiliated with the European Union.  So far, 2021 was the planet's fifth-warmest year on record. The two warmest years, according to the Copernicus group, were 2020 and 2016.
• 2023 could be the warmest on record: “It is actually almost a certainty that this will be the warmest year globally,” Michael Mann, a climate scientist and professor at the University of Pennsylvania, told USA TODAY. The current record for the warmest year is 58.69 degrees over the global land and ocean, set in 2016, during the last El Niño. Last year's global average was just below that, at 58.44 degrees.
• The Atlantic Ocean hit its highest temperatures since records began in 1850: Surface temperatures in the North Atlantic have hit "unprecedented" temperatures, almost 3 degrees warmer than typical for summer. The figure – the highest since in a series of temperature recordings that go back to 1850 – broke records "by a wide margin," according to England's Meteorological Office.

Yes, heat waves have always happened. But....

Heat waves have always happened. But the ones now are hotter and happening more often. A study published in May found that extreme heat of the magnitude Spain and Portugal experienced this spring should only have about a 1-in-400 chance of occurring in any given year. Temperatures there were 36 degrees higher than average for May this year.

Contributing: Dinah Pulver