Weather records are falling like dominoes around the globe this summer.
The Earth’s unofficial average temperature broke records last week. Daily high temperatures broke records in South Florida and Arizona. A Texas heat dome broke records in June and it was the planet’s warmest June on record.
The dizzying headlines are unlikely to slow down over the next few weeks, or in the years to come as climate change reshapes the world’s weather, making natural events more extreme.
“There’s a definite chance we will see record daily highs being broken a few more times over the next four to six weeks,” said Robert Rohde, lead scientist for Berkeley Earth, an independent non-profit focused on climate analysis.
Here’s why:
Here’s a breakdown to understand the records and how they’re calculated and set.
Could this year 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. “We can expect that combination of factors to supercharge weather events this summer in the form of extreme heat waves, drought, wildfire and flooding events.
A month ago, after processing May temperature data, Berkeley Earth put the odds of a record warm 2023 at 54%, slightly better than a coin flip, Rohde said.
Updated odds haven’t been calculated yet, but “now that June has come up as a scorcher, the probability has certainly increased,” Rohde told USA TODAY. It’s now “more likely than not that 2023 will set a new record for the warmest annual average.”
The current record for 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, 58.44 degrees.
How is the global average temperature determined?
For roughly the last 40 years, the average temperature has been derived from a data set that includes observations from satellites, land and the atmosphere, Rohde said.
To look at global average temperatures from the 1970s and earlier, scientists use data from weather stations, oceangoing ships and buoys, he said. Using that method, global temperatures can be reconstructed dating back to around 1850. That’s how scientists know it’s “as warm as it has ever been since humans began using technology to measure the temperature of the Earth,” he said.
How are other US weather records defined?
The National Weather Service collects data from weather monitoring stations across the country and keeps track of records, including daily highs and lows, the daily, monthly and annual average of the highs and lows, total rainfall, total snow and maximum wind gust.
The data can be complex, and the National Weather Service runs information submitted from individual weather stations through quality control routines to catch outlier values that appear to be unreasonable or inconsistent with nearby stations. Comparisons on the number of records broken among stations from year to year is difficult because a station established 35 years ago would break more records than stations taking measurements since the late 1800s.
While maximum and minimum temperatures are obvious, two other categories can be more confusing. A cool maximum occurs when the warmest temperature for the date is lower than it’s ever been before. These records still occur, but happen less frequently than warm records
A warm low occurs when the lowest temperature for a date is higher than it’s been before. This record occurs more often.
Records are reported in the following ways:
- Daily records: If, for example, it was 90 degrees in Daytona Beach on any given date and it had never been that high before on that date, it’s a new daily record for that date.
- Monthly and annual records: These can be used to describe days, months and years, including the average of the highs and lows combined.
- All-time record: When it’s the highest or lowest temperature, rainfall or snow ever in recorded history at any given monitoring station, it checks all three boxes: a daily record, a monthly record and an all-time record.
Are warm records being broken more often?
Yes. Statistically weather records could be compared to a Bell curve, with the most frequently observed temperatures along the high peak of the curve and the unusually warm and cold temperatures at either end where the curve tapers off, said Karin Gleason, chief of the monitoring section at NOAA’s National Centers for Environmental Information.
But, in stations across the globe, the curve has shifted to the right, Gleason said. Average temperatures have increased, and the frequency of new warm records being set has increased. Rainfall records also are set more often.
“We’re seeing more precipitation in high-intensity events than we have historically at a lot of stations,” Gleason said.
They’ve also documented a steep, rising trend in overnight low temperatures in many locations, driven by high humidity and clouds that hold in heat and interfere with overnight cooling. In many cases, she said, warmer overnight lows are pushing average temperatures higher more than the daily highs.
What global temperature record was broken during the week of July 4?
A new daily global record of 63 degrees was set Thursday, according to data from the University of Maine’s Climate Reanalyzer. The reanalyzer takes daily temperature and satellite observations and puts them into a model that constructs a representation of the temperature across the Earth on a daily basis, and dates back to 1979. Thursday’s high surpassed a daily high reached the two days before.
What does NOAA say about the apparent record?
NOAA, the official source of global temperatures and temperature records in the United States, said this week it couldn’t confirm the announcements from the Reanalyzer.
The Reanalyzer uses model output from NOAA’s National Centers for Environmental Prediction rather than actual temperature measurements and that output can’t be used as proxy for actual surface temperatures, the agency stated.
However, NOAA added: “We recognize that we are in a warm period due to climate change, and combined with El Nino and hot summer conditions, we’re seeing record warm surface temperatures being recorded at many locations across the globe.”
