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June 2023 may be remembered as the start of a big change in the climate system, with many key global indicators flashing red warning lights amid signs that some systems are tipping toward a new state from which they may not recover.

Earth’s critical reflective polar ice caps are at their lowest extent on record in the satellite era, with the sea ice around Antarctica at a record-low extent by far, spurring worried scientists to share dramatic charts of the missing ice repeatedly. In the Arctic, the month ended with the Greenland Ice Sheet experiencing one of the largest June melt events ever recorded, and with scientists reporting that June 2023 was the hottest June ever measured, breaking the 2019 record by a “staggering” 0.16° Celsius.

Globally, the oceans set records for warmth on the surface and down to more than 6,000 feet deep throughout the month, with temperatures so far above the norm that the conditions elicited more graphs showing the anomaly. They’ve been shared thousands of times by scientists, policymakers and the public. And in Canada, forest areas about the size of Kentucky have burned, choking huge swaths of central and eastern North America with acrid wildfire smoke, with some of the haze even reaching Europe.

There was record-breaking heat on nearly every continent during the month, according to independent climate statistician Maximilian Herrera. Along with the deadly late June heat in Mexico and the South-central United States, extreme readings have been widespread in remote Siberia, with hundreds of daily heat records, including readings higher than 95° Celsius close to the Arctic Circle. “The heat will just get worse,” he posted on Twitter.

Herrera also tracks notable regional extremes, like a historic mountain heatwave in Iran, where temperatures in late June spiked to between 100° and 120° Fahrenheit at elevations between 1,500 and 5,000 feet above sea level that are normally far cooler.  During the first week of July, temperatures in Iraq are forecast to breach 120° Fahrenheit.

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“These extraordinary extremes could be an early warning of tipping points towards different weather or sea ice or fire regimes,” said University of Exeter climate researcher Tim Lenton. “We call it ‘flickering’ when a complex system starts to briefly sample a new regime before tipping into it. Let’s hope I’m wrong on that.”

In the meantime, the tropical Pacific Ocean is shifting into the warm El Niño phase of a two- to seven-year Pacific Ocean cycle that can boost the average global temperature by 0.2° Celsius, enough to stoke the planet’s fever to a dangerous new high.

“The onset of El Niño will greatly increase the likelihood of breaking temperature records and triggering more extreme heat in many parts of the world and in the ocean,” said World Meteorological Organization Secretary-General Petteri Taalas. “Early warnings and anticipatory action of extreme weather events associated with this major climate phenomenon are vital to save lives and livelihoods.”

“I expect a step change to higher global mean temperatures starting this year,” said atmospheric scientist Kevin Trenberth, a distinguished scholar at the National Center for Atmospheric Research and honorary faculty at the University of Auckland. “And next year will be the warmest on record, either 1.4 or 1.5C above pre-industrial.”

The higher of those levels is the amount to which the United Nations’ 2015 Paris Agreement aspired to limit climate change, but the continued upward trajectory of global temperatures could make that goal impossible to reach.

“I expect it then to oscillate about that value and not come down again,” he said.

The El Niño temperature nudge comes against a backdrop of record-high carbon dioxide concentrations in the atmosphere, he said, adding that the rate of increase is as high as it has ever been and continues to accelerate.

“In other words, there is no bending down of the CO2 record, as should happen with all the new actions being taken in the U.S. and elsewhere,” he said. “The problem is that China and India are accelerating their coal-fired power stations and overwhelming all other cuts.”

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Antarctic Sea ice decline has a cascade of impacts

The persistence of the startling Antarctic sea ice decline may be one of the most puzzling and worrisome of the recent cluster of climate extremes. Until recently, researchers expected less sudden changes in Antarctica, because it’s such a vast reservoir of coldness, and surrounded by a continual swirl of ocean currents and winds that have buffered the continent to some degree.

But at the end of June, getting into the heart of the Southern Hemisphere winter, an area of ice about the size of Texas and Alaska, nearly 1 million square miles, was missing. As the Southern Hemisphere’s winter set in, the sea ice grew more slowly than ever observed in the satellite era.

The National Centers for Environmental Information (NCEI) has released new data showing that the shift to an ever-warming planet is rapidly accelerating. In the 3rd Annual U.S. Climate Extremes Index released this week, the NCEI found that extreme weather events in June 2019 indicate that certain climate components are rapidly approaching critical thresholds.

The report looks at extreme weather events in many areas, including temperature, precipitation, and drought. The data collected showed that extreme heat is the greatest concern. While still below previous records, 32 states recorded temperatures above their 20-year average between June and August, including 14 states that experienced average temperatures of 95 degrees F or higher. This increase in heat is part of a longer-term trend, as globally we continue to experience higher average temperatures.

The increase in heat also brought a rapid rise in both the number and severity of drought events. Over 30 percent of the contiguous United States experienced an extreme drought event for at least two consecutive weeks, with 11 states seeing the most dramatic effects. Although storms such as Hurricane Barry brought welcome rain to certain parts of the Midwest, the extreme drought will continue to devastate U.S. farmland for some time.

The NCEI findings are a stark warning that climate components are rapidly approaching critical thresholds. The effects of climate change are being felt more and more each year, and unless humanity takes decisive action, these extreme weather events are likely to become more intense. The time to act is now.

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