Why could tropical plankton lose more than polar plankton after global impact darkness?

Answer: Bigger sunlight loss

Bigger sunlight loss ✓ — Bigger sunlight loss is the counterintuitive answer. In the 2026 model, absolute irradiance reduction was greatest at low latitudes, so tropical plankton lost more of the light economy they relied on. Polar communities were already adapted to darker seasons, making some high-latitude survivors less shocked by the new light regime.

Colder starting water — Colder starting water sounds plausible because polar seas are harsh, but the model found temperature alone had limited power to reproduce the extinction pattern. The surprise is that light history mattered more than cold tolerance. A community already used to low light can be pre-adapted for a disaster that looks globally uniform from space.

Muddier seafloor — More seafloor mud is not the main filter for open-ocean plankton. Sediments preserve the fossil signal, but they do not explain why living cells survived. The geographic pattern points instead to how much sunlight vanished and whether local plankton were already good at low-light living.