Southern Ocean biology drove ancient global warming
An international team led by the Max Planck Institute for Chemistry found that Southern Ocean biological changes fueled Earth's warmest climate in 65 million years.
Fossil shells reveal carbon cycle shift
Researchers analyzed nitrogen isotopes in microscopic fossil shells from four Southern Ocean sites. These samples came from sediment cores collected by the Ocean Drilling Program between 53 and 49 million years ago. The data shows phytoplankton utilized approximately 40 percent less available nutrients during peak warmth. This decline indicates a substantially weaker biological carbon pump storing carbon in deep waters.
Modeling links ocean to air CO2
A numerical ocean-atmosphere model simulates physical and chemical interactions between the atmosphere and oceans. The reduction of 40 percent alone raises CO2 levels from 700 to about 900 parts per million. Including warming and seawater chemistry feedbacks increases this value to about 1,100 parts per million. This explains why at least half of the approximately 800 ppm increase occurred over that timeframe.
Fripiat explains ocean buffering limits
François Fripiat, a co-author of the study, notes Eocene seawater had lower capacity to buffer changes in CO2. Under current conditions, the effect of a diminished biological carbon pump on atmospheric CO2 would not be as significant. The findings suggest changes in Southern Ocean biological activity amplified global warming significantly.
Reported by one outlet
Only one outlet has published this. Nothing here has been checked against a second report, so read it as that outlet's account and follow the link below for the original.
Reported by
1 independent outlet. Headline as published. Links open the original report.