The Download: greener cement, and the biggest tech stories of 2023

+ The worst technology failures of 2023. The Titan submersible, lab-grown chicken, and GM’s wayward Cruise robotaxis all made our annual run-down of the worst in tech. Read the full list.

+ How 2023 marked the death of anonymity online in China. As Chinese social media platforms move toward requiring users to disclose more information about their real identities, will we lose what made us want to be online in the first place? Read the full story.

+ Why last year marked the first time gene editing finally started living up to its potential.

+ Four trends that changed AI in 2023. Endless product launches, boardroom coups, intense policy debates, and a race to find the next big thing. Read the full story.

+ Take a look back over all the climate records that were broken in 2023, from greenhouse-gas emissions from fossil fuels to highest-ever temperatures.

+ But it wasn’t all bad news. There was some good climate news in 2023. Really! Read about the reasons for optimism.

The race is on to save coral reefs—by freezing them

As sweltering ocean temperatures make graveyards of coral reefs across the Caribbean and beyond, a team of scientists is scrambling to cool corals down. Way down. To -200 °C. 

Coral reefs, as an ecosystem, are expected to go functionally extinct by 2035. Now, scientists hope to freeze enough coral sperm, larvae, and adult polyps not just to support current conservation efforts, but to reboot reefs in the increasingly likely event of a marine mass extinction. Yet major engineering hurdles still stand in the way of this plan. Read the full story.