July is on track to become Earth's hottest month on record, climate scientists say

Image: Hot weather
A girl cools off in Washington Heights in Manhattan during a July 2019 heat wave. Copyright Mike Segar Reuters
By Denise Chow with NBC News Tech and Science News
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Even with more than a week left until the end of the month, experts are already anticipating that the current record from July 2017 will fall.


July is on track to become the hottest month in recorded history, climate scientists say, after heat waves blanketed North America and the Arctic saw warmer than usual temperatures. It's the latest sign that the planet's overall climate is warming, and that human activities are causing extreme events such as heat waves to become more likely and more intense, the scientists say.

Even with more than a week left until the end of the month, dozens of experts are already anticipating that the current record from July 2017 will fall.

"It's looking like there's a strong likelihood that we will end up with the warmest month ever," said Brian Brettschneider, a climate researcher at the University of Alaska Fairbanks.

In July 2017, when the previous record was set, average global temperatures were 2.16 degrees Fahrenheit higher than the 20th century average for July of 57.8 degrees Fahrenheit, according to the National Oceanic and Atmospheric Administration, which collects climate data and tracks temperature records. This July is expected to narrowly surpass the average temperatures from two years ago, scientists who study climate patterns say.

"Of course, we won't know until all the tallies are in, but we're on a good pace right now to beat that record," said Jack Williams, director of the Center for Climatic Research at the University of Wisconsin-Madison.

Dozens more climate scientists have echoed the prediction on Twitter.

"July is the warmest month of the year globally. If this July turns out to be the warmest July (it has a good shot at it), it will be the warmest month we have measured on Earth!" Michael Mann, a climate scientist at Pennsylvania State University, tweeted July 15.

In an email Tuesday to NBC News MACH, Mann called the new record "likely," saying there's now a "greater than 50/50" chance that the month will set a new high temperature.


July's anticipated milestone comes on the heels of another worrisome climate record: last month was the hottest June since record keeping began in 1880. Average global temperatures last month were 1.71 degrees Fahrenheit higher than the 20th century average for June of 59.9 degrees Fahrenheit, according to NASA and NOAA, which independently track global surface temperatures.

This summer has been a scorcher for much of the world, withEurope suffering through an intense heat wave in late June that saw the highest temperature ever recorded in France. This past weekend,about 169 million people across the United States were under heat alerts as temperatures in cities such as New York City; Little Rock, Arkansas; and Memphis, Tennessee, climbed into the triple digits. And this week, another heat wave is expected to hit parts of Western Europe.

While steamy temperatures are expected in June and July in the Northern Hemisphere, Williams said this summer's record-setting heat is far from normal.

"The climate system right now is like a batter on steroids," Williams said, using a baseball analogy. "Heat waves of today are going to be the normal events of tomorrow."

Mann said the recent warming trends demonstrate the profound impact of climate change on the planet.

"It's part of a worrisome pattern of streaks of broken records which, we have shown simply would not be occurring in the absence of climate change," Mann said. "This is just one additional confirmation, along with the spate of unprecedented extreme weather events we've seen in recent years, of the fact that the impacts of climate change are no longer subtle. They are staring us in the face."

Human activities — primarily from burning fossil fuels — emitcarbon dioxide and other greenhouse gases that trap heat in the atmosphere. Increasing greenhouse gas emissions is associated with warmer global surface temperatures; the planet's 10 hottest years on record have all fallen in the past two decades, according to Climate Central.

"There's internal fluctuations in the climate system that cause the needle to metaphorically bounce around from year to year, but the trend is unmistakable," Brettschneider said.

Unless significant measures to curb greenhouse gas emissions are adopted, scientists expect temperature records to keep falling. Scientists say global temperatures could increase by at least 3.6 degrees Fahrenheit this century — creating conditions on Earth that have not been seen in more than 2 million years.


"The closest equivalents were found in the Pliocene [Epoch], when sea levels were higher by tens of feet and it was a much warmer world," Williams said. "That was a time period prior to human evolution. Part of the bigger picture here is we're pushing the climate system toward states that we haven't seen in our societal experience — and even in our species' experience."

The current warmest year on record was 2016, when a naturally recurring climate pattern known as El Niño contributed in part to warmer-than-usual conditions. So far this year, the period from January through June has tied 2017 as the second-hottest year to date on record,according to the NOAA.

For Williams, the record temperatures add urgency to efforts to sound the alarm on climate change.

"It's tough being a climate scientist and seeing the trends that we're heading towards and trying to raise awareness," Williams said. "It feels like an uphill battle. At the same time, I feel like this is the defining issue of my generation, and it's a fight and conversation worth having. It's important work, so we just keep at it."

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