It is correlated with ocean acidification and anoxia.
If a palynologist studying a lake sediment core finds predominantly spruce pollen at the bottom of the core, and grass pollen at the top of the core, he or she would suspect that this process had occurred. This process is accompanied by a decrease in the relative degree of unsaturation of phytoplanktonÂ­derived alkenones. Approximately 55 million years ago, a large occurrence of this process caused a mass extinction of benthic foraminifera and an increase in dinoflagellates; that happened at the (*) PaleoceneÂ–Eocene boundary. This change is accompanied by an increase in the isotopic abundance of oxygenÂ­18 in ice cores. This process occurred during the beginning of the Holocene after the Younger Dryas, and it has been gradually happening since the end of the last glacial maximum 25,000 years ago. It is correlated with ocean acidification and anoxia. For 10 points, name this most famous effect of increases in global CO2, which has recently been driven by humans.
If a palynologist studying a lake sediment core finds predominantly spruce pollen at the bottom of the core, and grass pollen at the top of the core, he or she would suspect that this process had occurred.
global  warming  [accept any answer indicating that  temperature  increased like "climate change"]