Oxygen deficient zones

Enhanced ocean oxygenation during Cenozoic warm periods
In the last 50 years, oxygen-deficient zones in the open ocean have increased…Less oxygen dissolves in warmer water, and the tropical ocean’s layers can become more stratified. But how will this development continue, and what happened in past warm periods?

A team led by Alexandra Auderset and Alfredo Martínez-García at the Max Planck Institute for Chemistry in Mainz has shown in a recent study that, in the open ocean, oxygen-deficient zones shrank during warm periods of the past…

Using nitrogen isotopes from foraminifera, the scientists from Mainz and Princeton University showed that denitrification of the water column in the eastern tropical North Pacific was greatly reduced during two warm phases of the Earth’s modern era, the Cenozoic, about 16 and 50 million years ago.