Jul 17, 2023 - Energy & Environment

What this summer's weather reveals about climate change

Illustration: Annelise Capossela/Axios

Monitoring the planet's climate this summer can give one the impression that the climate system — which includes the oceans, atmosphere, ice sheets and more — has gone off the rails.

Why it matters: The blitz of extreme weather events is posing dangers to life and infrastructure, and exposing our vulnerabilities even at today's relatively modest level of warming, about 1.2°C (2.16°F) above preindustrial levels.

The big picture: This past weekend alone featured dangerous heat in the Southwest and West; Miami's first "Excessive Heat Warning;" explosive, dark and angry clouds erupting from massive wildfires in British Columbia; and more.

Meanwhile, climate scientists are raising alarms about global trends. The planet is coming off the warmest June on record, with temperatures likely to climb even higher in July. The oceans, especially the North Atlantic, are off-the-charts warm.

  • Far to the south, Antarctic sea ice cover has precipitously dropped in a development that has scientists searching for answers.

The intrigue: Climate studies have warned about an uptick in simultaneous heat waves occurring in the Northern Hemisphere. That's partly due to the contortions of the jet stream, which helps to steer and power storm systems.

  • One such study published last year found concurrent heatwaves are becoming more intense and affecting larger areas, with a nearly sixfold increase in their frequency in the most recent decade compared to the 1980s.
  • Initial signs point to a particularly slow-moving or even stuck jet stream pattern known to favor heat waves as potentially related to the extreme heat in the U.S., Europe and China, University of Pennsylvania climate scientist Michael Mann told Axios via email.
  • Research that Mann and his colleagues have published shows that climate change may be increasing the chances that such weather patterns will develop.

Between the lines: Andrew Dessler, a climate scientist at Texas A&M University, says what is happening now demonstrates that the climate is a non-linear system.

  • "In a linear system, changes occur in a straight line. If climate impacts were linear, each 0.1°C increase in temperature would produce the same increment of damage," he tells Axios in an email.
  • He notes, however, that the built and natural worlds each have thresholds, beyond which severe impacts can occur.
  • This might be the clearance of a bridge above a suddenly raging river during a flash flood, or a temperature threshold above which bark beetles can survive once-frigid Western winters.
  • "Each 0.1°C of additional warming will surpass an increasing number of thresholds in the climate system. We will see more and more "sudden" climate impacts that have never happened before," he adds.

What they're saying: Friederike Otto, a climate scientist at Imperial College London, cautioned against thinking that we've reached a "new normal," since that implies a semblance of stability.

  • "We’re nowhere near a normal, we’re in a phase of accelerated warming, because we are still increasing greenhouse gas emissions. The result is the weather we see," she told Axios via email.
  • "Whenever we stop burning fossil fuels we can begin to figure out what 'normal' means again."

The bottom line: As scientists investigate whether human-caused climate change has caused additional thresholds to be crossed this summer, it's time to prepare for more surprises.

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