Hope you were able to enjoy summer before this school year -- if unusually intense heat and storms didn't made outdoor activities uncomfortable or impossible. It was an extra-wet, extra-steamy season in some U.S. regions. Globally, the planet reached an alarming milestone: September was the fourth straight month Earth set a new record high temperature, assuring that 2023 will be the globe's warmest year on record.

It's part of a pattern of extremes that climate scientists say are becoming more frequent and more intense as the planet continues to warm. All of this could be the start of a "new normal," in other words. "The latest climate change news amounts to a whole bank of sirens flashing and howling," clean energy newsletter editor David Roberts tweeted last week.

Twenty-three U.S. weather disasters with damage of at least $1 billion have happened already in 2023 – a record since the National Oceanic and Atmospheric Administration began cost-tracking in 1980. Eighteen of those events were from severe thunderstorms and tornadoes, while others included California flooding and a deadly August wildfire on the Hawaiian island of Maui. Also in the tally are flash floods in July from intense rain in Vermont, New York, Pennsylvania and Connecticut. In addition, choking smoke from vast Canadian wildfires made Americans uncomfortable in the Northeast and Midwest.

"In the long-term trends, we are moving out of society's comfort zone," NASA climate scientist Gavin Schmidt told PBS last month (see video below). And that means that places that were prepared for a certain spread of temperature and a certain number of extremes are now being hit with larger extremes. They're being hit with higher temperatures, more intense rainfall. . . . The frequency and intensity of these features is increasing." Scientists predict 2024 will likely break records again.

Experts say this past summer's floods, strong hurricanes and heat waves show why it's vital to reduce use of oil and coal and gas ("fossil fuels") that are the main cause of man-made climate change. Renewable energy sources such as wind, solar and battery power are lower-impact alternatives. "What we choose to do as a society makes a difference to how much warmer it's going to get," says Schmidt of NASA. "Unfortunately, it's very hard to go back. . . . But we're not baked into further increases and further acceleration in that [climate change] system."

Professor says: "By now, we should all be used to individual heat waves being connected to global warming." -- Gabriel Vecchi, Princeton University geoscientist

European expert says: "The sense of urgency for ambitious climate action has never been more critical." -- Samantha Burgess, deputy director of the Copernicus Climate Change Service, a European Union agency in Reading, England

Journalist says: "Many Americans are looking to their future summers and wondering if they will ever be the same." – Julie Bosman, writer of a New York Times climate project this month