These 5 statistics show why we're experiencing historically hot weather

You’re not imagining it: This summer has been a really hot one.

Last month was the hottest June ever, according to a new report from the National Oceanic and Atmospheric Administration -- and it was the overall hottest first half of the year in South America, Mexico, New Zealand, Madagascar and other parts of southern Africa.

As millions of people prepare to face scorching temperatures across the U.S. this weekend, scientists are warning that unless major changes are made, we’d better brace for more heat moving forward.

“The bottom line is the Earth is one degree Celsius or 1.8 degrees Fahrenheit warmer today than the pre-industrial time period," said Brenda Ekwurzel, Director of Climate Science at the Union of Concerned Scientists. "What that means is that what used to be a rare hot day or high temp record is now the new normal for our summers.”

“What's worse is we are getting into rare heat temperatures for locations that would not have been possible if it were not for human-induced climate charge,” she said.

Scientists have long stressed that the reason for the uptick in the global temperature stems from human activity, particularly the burning of fossil fuels, which drives up the amount of carbon dioxide in the atmosphere, leading to the increased temperatures.

These key statistics illustrate why we're in a period of record heat:

- June 2019 set a new record for hottest June ever. According to NOAA, the temperature across land and oceans was 1.71 degrees Fahrenheit above the 20th century average. That’s a big deal because the previous record came in June 2016 and this year’s temperature was 0.04 degrees Fahrenheit above that figure.

- June marked the 414th consecutive month where temperatures were recorded as being above the 20th century average for that given month, according to NOAA. That’s a trend spanning more than 34 years.

- Nine of the 10 warmest Junes on record have occurred since 2010, per NOAA.

- Global sea level has risen about 7 to 8 inches since 1900, and nearly half of that increase -- 3 inches -- has occurred since 1993, according to the latest climate assessment, published last year by the U.S. Global Change Research Program.

- Heatwaves happen more frequently since the 1960s and extreme cold temperatures or cold waves happen less frequently, according to the climate assessment.

The Union of Concerned Scientists has released a report about the future of dangerously hot days, with a tool that allows users to type in their city and see how many times in the last century they experienced extremely hot days, along with how many of those days they can expect in the middle of this century, from 2036 to 2065, and in the late century, from 2070 to 2099, if current trends continued.

In New York City, for instance, on average there were only two days of 100+ degree temperatures per year between 1971 and 2000 -- but the tool shows that by mid-century, if trends continue, there will be an average of 20 such days per year and by late century there will be 42.

Even more dramatically, in Houston, Texas, on average there were 10 days of 105+ degree temperatures per year up until the year 2000 -- but by mid-century, the tool predicts that if trends continue there will be an average of 69 such days per year, and by late century there will be 108.

“The hot places are getting hotter and places that weren’t as hot are reaching thresholds that are dangerous for human health,” Ekwurzel said.