In Warming World Oceans Risk Mass Extinctions, Model Shows

“‘How screwed are we?’ I get that all the time,” Dr. Deutsch said. “If we don’t do anything, we’re screwed.”

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Extreme heat. A heat wave has been pummeling India and Pakistan for weeks, and it is expected to intensify. The scorching weather is a reminder of what lies ahead in an era of climate change, as heat waves grow more frequent, more dangerous and longer-lasting.

Nations are still far from taking the necessary steps to prevent catastrophic climate change. Last month the secretary general of the United Nations, António Guterres, warned that a critical goal — restricting average global warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) since preindustrial times — was “on life support.”

The International Energy Agency, a group created to ensure a stable worldwide energy market, said last year that countries must immediately stop approving new fossil fuel projects. They have not stopped, and Russian’s invasion of Ukraine has added to calls for more drilling in the name of energy security.

In an interview, Drs. Deutsch and Penn said they feel like the ignored scientists in “Don’t Look Up,” the recent movie in which a comet hurtling toward Earth is a metaphor for climate change. As in the film, the planet is at a pivotal moment, giving people living today outsized power in determining the future.

“Great power brings great responsibility,” Dr. Deutsch said. “And we’re learning about our power, but not about our responsibility — to future generations of people, but also to all the other life that we’ve shared the planet with for millions of years.”

Pippa Moore, a professor of marine science at Newcastle University in England who studies the impacts of climate change on the ocean and was not involved with the study, called it comprehensive.

“This paper adds to the huge body of evidence that unless more is done to curb our greenhouse gas emissions, our marine systems are on course to see a massive shift in where marine species live and, as shown in this paper, significant extinction events that could rival previous mass extinction events,” she said.

Brad Plumer contributed reporting.