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As July comes to an end, scientists believe the month is likely to be the hottest month on Earth in more than 120,000 years.
This month, there have been concurrent heat waves in North America, Europe and Asia.
The hottest days recorded on Earth, in terms of a global average temperature, were recorded this month, according to a University of Maine climate science data visualization tool.
This follows June’s distinction as the hottest month on record, and scientists say 2023 is shaping up to be the hottest year on record globally.
“Climate change is here. It is terrifying. And it is just the beginning,” United Nations Secretary-General Antonio Guterres told reporters in a briefing in New York on Thursday. “The era of global warming has ended; the era of global boiling has arrived.”
In Maine, Portland broke a record earlier this month, and then set a new one days later, with 28 straight days when the overnight low temperature was above 60 degrees.
While that may not sound that hot, a rise in overnight low temperatures is concerning for many reasons.
On a human level, high temperatures at night mean that the body doesn’t have a chance to cool down. This can stress and damage the heart and other organs. In addition, heat can disrupt sleep patterns, which can further stress the body and can lead to mental stress. The consequences are usually worse for older people and people with low incomes.
On an environmental level, higher overnight temperatures, especially in dense cities, mean that pavement, buildings and other things that trap heat during the day will have less opportunity to cool. This can exacerbate an overall warming trend.
Additionally, hot nights prompt more use of air conditioning, increasing demand for electricity, much of which is generated by burning fossil fuels, which traps more heat in the atmosphere.
While record high temperatures have been getting a lot of attention this summer, the rise in overnight low temperatures has been more dramatic.
Overnight lows in the U.S. are rising twice as fast as daytime highs, according to an analysis by Climate Central, a nonprofit research and news organization. Overnight lows in the contiguous U.S. have risen by 2.5 degrees F on average since 1970.
Last year, two-thirds of the contiguous states experienced extremes in minimum temperatures, according to data from the National Oceanic and Atmospheric Administration.
The places with the biggest increases were not all in what we typically consider hot weather states. Salt Lake City, Utah, saw a 7.3 degree increase and overnight temperatures in Boise, Idaho rose by 6.9 degrees. The largest increase was in Reno, Nevada, where overnight low temperatures rose by 17.3 degrees since 1970.
“The reason that setting new temperature records is a big deal is that we are now being challenged to find ways to survive through temperatures hotter than any of us have ever experienced before,” University of Wisconsin-Madison climate scientist Andrea Dutton told the Associated Press in a recent email. “Soaring temperatures place ever increasing strains not just on power grids and infrastructure, but on human bodies that are not equipped to survive some of the extreme we are already experiencing.”
The record high temperatures, both during the day and at night, are yet another warning that should spur much more serious action to reduce greenhouse gas emissions to slow the warming of our planet.
