Summer has barely began within the Northern Hemisphere, however already it’s providing an oppressive preview of life on a hotter planet.
Europe has endured two lethal, record-shattering heat waves in a matter of weeks, with a third on the way in which subsequent week. Now, the United States is experiencing its personal blast of harmful heat, notably within the East, which is dealing with skyrocketing temperatures and excessive humidity.
These episodes have been triggered by intense heat domes — cussed areas of excessive strain that lock sizzling air in place — and are clearly supercharged by global warming, consultants say.
The strengthening of El Niño and record-high worldwide ocean temperatures may very well be amplifying the heat, too.
“There’s no question that record sea surface temperatures like we’re seeing right now — which are due partly to El Niño, and partly to longer-term human-caused warming — fuel more extreme weather, since warmer oceans mean more moisture in the atmosphere which is available to intensify storms systems and produce heavy rainfall,” mentioned Michael Mann, a local weather scientist on the University of Pennsylvania.
“The record global [ocean] temperatures also mean more extreme heat,” he mentioned.
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The hyperlink between local weather change and heat waves like we’ve seen this spring and summer time is very robust, easy and effectively understood. As the planet warms, excessive heat occasions have gotten extra frequent, intense and long-lasting.
A speedy examine on Europe’s most up-to-date heat wave, launched late final week, discovered that not solely was it Europe’s worst heat wave on report, but additionally these extraordinary temperatures would have been “virtually impossible” simply a few a long time in the past, when human-caused international warming was much less extreme.
“Make no mistake, the primary driver for the uptick in deadly heat waves across the world is the burning of fossil fuels, given that a modest baseline warming drives an exponential increase in extreme heat,” mentioned Kim Cobb, a local weather scientist at Brown University.
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El Niño is well-known to amplify international common floor temperatures and is anticipated to lead to a report heat 12 months in 2027, whereas boosting temperatures this 12 months to some extent as effectively.
It also can lead to each marine heat waves and excessive heat over land, however these impacts are usually seen a few months after an El Niño has fashioned and strengthened, reasonably than straight away. The ongoing El Niño was declared on June 11, making it a latest climate function.
Michael Tippett, a local weather scientist at Columbia University who research the ties between El Niño and climate patterns, mentioned that on common, there is no such thing as a robust hyperlink between El Niño and shifts in summer time climate patterns over the US and Europe.
Instead, he mentioned El Niño tends to considerably affect the climate within the fall and winter in these areas.
However, Cobb mentioned whereas there isn’t a clear tie between El Niño and large-scale summertime heat waves, usually, this specific El Niño is uncommon in a number of respects. This makes its impression probably distinct from previous occasions.
“This El Niño is unusually large for this early in the year, and it is occurring in a warmer climate that is fundamentally different than past decades. We learn something new from every event, driving new areas of research to improve our understanding of El Niño impacts in a warming world,” Cobb mentioned.
Even if El Niño is simply taking part in a minor position within the excessive heat of late, it’s seemingly to turn out to be a star participant by subsequent summer time, which may yield much more excessive heat episodes world wide.
Mann pointed to one other issue concerned in latest heat dome-dominated extremes — the jet stream — which can have been half of the European heat wave that’s lastly starting to subside, in addition to the US heat wave that’s simply ramping up. The jet stream is a freeway of air at excessive altitudes which steers climate techniques.
When the jet stream could be very wavy and sluggish to shift into a totally different sample, it will probably lead to excessive outcomes, similar to heat domes that don’t budge for days to even weeks.
“The tendency of the jet stream, during the warm half of the year, to get locked into very stable, wavy configurations … favors persistent weather extremes,” he mentioned. The heat domes have a tendency to type the place the jet stream turns northward, shifting up and over the dome itself and main to robust flows of sizzling air from the south to the north close to the Earth’s floor.
Mann and his colleagues have shown an uptick within the frequency of such caught jet stream patterns, often known as planetary resonance occasions, in latest a long time. That pattern coincides with elevated international warming.
“We do know that it has been associated with many of the most extreme heat waves we’ve seen in recent decades,” Mann mentioned.