Extreme heat has blasted Europe and the US this week, causing wildfires, power cuts and huge spikes in ocean temperatures, in the latest evidence that 2023 is shaping up to be a record-breaking year for the climate. Here are the most shocking records to tumble in the past seven days.
July set to be world’s hottest month on record
This month has proved to be a truly extraordinary one for the global climate. The first week of July was the hottest recorded on Earth since instrumental measurements began in the 1850s, with 6 July the hottest day on record. There has been little let up in the weeks since, with July 2023 “extremely likely” to become both the hottest July on record and the hottest month ever, according to the World Meteorological Organization.
The record-breaking spell has largely been driven by intense heat in the northern hemisphere, which has entered its peak summer period and has been repeatedly hit by severe heatwaves.
Preliminary data from the US National Oceanic and Atmospheric Administration (NOAA), compiled by the University of Maine’s Climate Reanalyzer, suggests the past week has been the hottest on record for the northern hemisphere, with the average global air temperature recorded 2 metres above Earth’s surface peaking at 22.62°C (72.72°F) on 25 July.
“This has been a crazy summer,” says Pedram Hassanzadeh at Rice University in Texas. He says this kind of “hemispherical scale” extreme event is driven by a wavier-than-normal band of powerful, high-altitude winds known as the jet stream, which could be linked to rising greenhouse gas emissions.
Greek wildfire emissions highest on record
Wildfires have swept through the Greek islands of Rhodes, Corfu and Evia and pummelled the mainland in recent days, forcing thousands of local people and tourists to flee their homes and hotel complexes. On 26 July, the European Union’s satellite monitoring service Copernicus said that wildfire emissions across Greece have increased rapidly since 17 July, climbing to their highest July level since records began in 2003. Between 17 July and 25 July, the fires emitted more than 1 million tonnes of carbon dioxide, Copernicus said, almost double that of the previous most polluting year in 2007.
It isn’t just Greece experiencing problems. Copernicus warned that the situation on the Italian island of Sicily is “worsening”, with nearly 50 fires detected and “significant carbon emissions” expected in the coming days. Algeria and Tunisia are also experiencing severe wildfires, it noted.
‘Hot tub’ water temperatures in Florida
Water temperatures in Florida Keys Bay hit their highest-ever levels on 24 July, with a water buoy south of Miami reading 38.4°C (101.2°F), way above the normal reef temperature of 29.4°C (85°F) for this time of year.
If verified, the reading would be a new world record for the warmest ocean waters ever recorded, outstripping the previous – albeit unofficial – record of 37.6°C (99.7°F) in Kuwait Bay in 2020.
The surging water temperatures may devastate marine life, with NOAA raising its coral bleaching warning system in the Florida Keys to level 2, its most severe level.
Scientists growing corals in offshore nurseries along the Florida Keys are racing to relocate them to cooler waters on land. Cindy Lewis at the University of South Florida is part of the rescue effort. “It’s been a flurry of activity from all of the partners to bring corals in and get them essentially into captivity and into safety,” she says.
She says the heatwave has been emotionally challenging for many researchers, many of whom have spent years trying to revive the health of Florida’s corals. “It’s a huge emotional drain on everybody,” she says. “You can see it in their faces, you can see it in their eyes. It brings many of them to tears, it honestly does.”
Record temperatures in the Mediterranean Sea
This week saw the highest water temperatures ever recorded in the Mediterranean Sea. On 24 July, the daily median sea surface temperature reached 28.71ᵒC (83.68°F), beating the previous record of 28.25ᵒC (82.85ᵒF) set in August 2003. Temperatures have remained high throughout the rest of the week, according to Spain’s Institute of Marine Sciences (IMS), hovering at around 3°C above average for the time of year.
Water temperatures are highest around the coast of Italy and Tunisia, says Justino Martínez at IMS. The marine heatwave, which is likely to cause severe coral bleaching, is probably partly due to the severe heat that has gripped much of southern Europe during July, he says.
Scientists would usually expect temperatures in the Mediterranean Sea to peak later in the summer, says Martínez. “Statistically, the highest value is reached at the end of August,” he says. That means even higher temperatures are possible next month.
Second record hot midnight in Death Valley
On 23 July, midnight temperatures in Death Valley, California, once again reached 48.9°C (120°F), according to data from the Badwater weather station maintained by the US National Weather Service.
It is the second time in a month that temperatures in Death Valley have hit that peak, which is likely to be a new world record for the hottest midnight in recorded history.
Other parts of the US Southwest have seen regional records tumble in the past week, with El Paso, Texas, experiencing a record-long streak of 40 consecutive days with temperatures above 37.8°C (100°F). In Phoenix, Arizona, every single day in July up to at least 26 July has registered temperatures above 43.3°C (110°F).