In a worrying milestone, June marked the 12th consecutive month of global warming of 1.5 degrees Celsius or more – the internationally accepted threshold for avoiding the worst effects of climate change.
A stifling month marked by heat waves and heat deathsJune was also about a quarter of a degree warmer than the warmest June on record in 2023, according to a report by the European Union's Copernicus Climate Change Service. 13th consecutive month to break its own monthly heat record.
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The persistent rise in the planet's temperature is “more than a statistical oddity and highlights a large and ongoing change in our climate,” Copernicus director Carlo Buontempo said in a statement.
“Even if this particular streak of extremes ends at some point, we are likely to see new records as the climate continues to warm,” he said. “This is inevitable unless we stop adding [greenhouse gases] “to the atmosphere and the oceans.”
The 1.5 degree Celsius threshold — about 2.7 degrees Fahrenheit — was set in the 2015 Paris agreement. Under that deal, the United States and nearly 200 other countries agreed to limit the rise in global average temperatures to no more than 2 degrees Celsius above preindustrial levels (and preferably below 1.5 degrees Celsius) to reduce the worst effects of climate change.
The pre-industrial period refers to an era before humans began significantly altering the planet's climate through fossil fuel and other heat-trapping emissions, and is typically measured using temperature data from between 1850 and 1900. According to Copernicus, the June global average temperature of 16.66 degrees Celsius (61.98 degrees Fahrenheit) was exactly 1.5 degrees Celsius above the estimated pre-industrial average.
The unprecedented year-long period is “very noteworthy and concerning,” said Brenda Ekwurzel, a senior climate scientist at the Union of Concerned Scientists, a national nonprofit.
However, exceeding 1.5 degrees Celsius for one year does not necessarily mean that humanity has failed to meet its goal, as the Intergovernmental Panel on Climate Change has not officially defined how many years of warming above 1.5 degrees Celsius are needed to exceed that threshold.
It's a topic of much scientific debate, Ekwurzel said, but many experts have suggested the limit should refer to a period of at least 10 years of warming to that temperature.
“It’s important to note for humanity – for all life on the planet – that we’ve been hovering around what the Paris agreement set as the threshold, and this may be the first year of that 10-year average,” he said. “It means we’ve already logged a year on that record.”
The benchmark is not merely symbolic. A 2018 IPCC special report outlined a worrisome future based on 1.5 degrees Celsius of warming, with various emissions scenarios leading to more deadly heat waves, droughts, floods, famines, ecosystem destruction, and public unrest and political destabilization, among other outcomes.
Rising global temperatures have already contributed to a rise in heat-related illnesses and deaths, including 1,300 deaths during this year’s Hajj pilgrimage in Saudi Arabia. Last year, a record-breaking 31-day heat spell in Phoenix contributed to about 645 deaths, while a heat wave in California in 2022 killed about 395 people.
“We have not yet changed our cultural patterns to adapt to this reality of climate change,” Ekwurzel said. “The timing of our sporting events, the timing of our cultural activities, was based on the ancient temperature.”
It's not just land surfaces that are boiling over. Non-polar sea surface temperatures in June were 69.53 degrees, the highest value on record for the month, according to Copernicus. It was the 15th consecutive month that sea surface temperatures have been the warmest on record.
The high temperatures occurred even though El Niño, the tropical Pacific weather pattern associated with global warming, was on the wane. Scientists say El Niño contributed to the record-breaking global heat of recent months and had hoped its dissipation would produce some cooling.
That could still happen in the coming months, particularly as a La Niña pattern develops later this year, but the persistent warmth signals a “kind of departure from natural cycles,” Ekwurzel said.
“Once the ocean warms, it is harder to cool it because it has a very high thermal capacity,” he explained. He added that warm ocean waters can be dangerous for marine life and people on land, as they can generate stronger winds, storms and waves.
The Atlantic Ocean is expected to experience an active hurricane season this year. Hurricane Beryl in the Caribbean has already become the earliest storm on record to reach Category 5 strength.
Seasonal forecasts indicate high temperatures will persist in the coming months. According to the National Oceanic and Atmospheric Administration, nearly all of the United States is projected to experience warmer-than-average temperatures in July, August and September, with the highest likelihood of above-normal conditions in the Four Corners region and the far Southeast.
A dangerous heat wave that began in California last week brought triple-digit temperatures across the state and contributed to a series of wildfires.
The soaring temperatures have also prompted a federal response. Last week, the U.S. Department of Labor’s Occupational Safety and Health Administration unveiled a proposal to set heating standards for 35 million workers in indoor and outdoor spaces, following California’s lead.
The Federal Emergency Management Agency is also facing growing pressure to expand its definition of “major disasters” to include extreme heat, which advocates say will open new funding avenues for cities and states struggling to deal with the growing threat.
Ekwurzel said it is not too late for humanity to change course and avoid the 1.5 degree Celsius limit. However, urgent action and emissions reductions will be necessary.
“The Earth, the ocean and the atmosphere are telling us that we have to act very quickly if we have any chance, and many, many, many people are losing hope,” he said. “We are better off adapting to this world with a temperature increase of 1.5 degrees Celsius. Many people are saying that this is probably the coldest decade of the 21st century.”
