Climate change since the 1950s has doubled the amount of time per year that millions of people around the world must endure heat so extreme that everyday physical activities cannot be done safely, a new study concludes. Instead of relying on simple measures of heat danger, the researchers used a modeling approach to estimate how much physical activity people of varying ages could perform in different ranges of heat and humidity without their core body temperature rising uncontrollably. Several areas across the South and Southwestern U.S. show hundreds of hours a year of severe limitations.

First study to use crowdsourced comments to assess effects of heat underground. Researchers collected comments from X and Google Reviews published between 2008 and 2024. Study focused on subway systems in Boston, New York and London. As above-ground temperatures rise, below-ground thermal complaints increase. Knowing when people are uncomfortable could inform targeted interventions.

Hitchhiking bacteria dissolve essential ballast in “marine snow” particles, which could counteract the ocean’s ability to sequester carbon, according to a new study.

As any diver knows, oceans can be cloudy places. Even on sunny days, snow-like particles drift through the water column, obscuring the aquatic world below.

Scientists have long known that this “marine snow” carries inorganic calcium carbonate – the building block of shells – but couldn’t explain how the mineral dissolves in the upper part of the ocean.

New research from Rutgers University-New Brunswick points to the culprit: bacteria.“Think of marine particles as the megacities of the ocean,” said Benedict Borer, an assistant professor of marine and coastal sciences at the Rutgers School of Environmental and Biological Sciences and lead author of the study published in the journal Proceedings of the National Academy of Sciences. “Within these tiny spaces, there are huge amounts of microbial activity. It’s here where calcium carbonate dissolves.”