How can they deduce human population from global CO2 levels? Humans are far from being the dominant form of biomass, even when accounting for oxygen-breathing biomass only.

Edit: The real paper says "Reconciling ice core CO2 and land-use change following New World-Old World contact". Journalists doing the journalism thing again.

Cheers, I wish the OP just linked to the paper instead of the news article which would have included way less cringe worthy summaries and an actual summary worthy of our attention.

I've stopped reading science news for exactly that reason.

Fun fact. My uncle is a professor of geosciences and goes on expeditions to drill these cores in Antarctica, analyzing their gas contents back at the university. When we'd visit my uncle and his family. My Dad and uncle would commonly head to the university and collect cores which were set to be disposed of and make martinis with 40,000+ yr old ice. The gases have been compressed over time and the weight of the ice, so it would crackle as it melted.

I feel like this is a beginning of a movie where a terrible bacteria gets frozen for 40,000 years and then someone puts it into a martini and it causes a worldwide outbreak.

Title is a little misleading. "Gas From Ice Cores Traces Population Fluctuations" would be more accurate.

It's not actually about a moment when 56M people died, which the title suggests.

Linking a block of ice to colonization is so 2023.