Increase in warming climate has intensified the carbon dioxide level in atmosphere which is released by oceans, new research has suggested.
Scientists studied a 26,000-year-old sediment core taken from the Gulf of California to find out how the ocean's ability to take up atmospheric CO2 has changed over time.
Researchers found that in those periods when silicon was least abundant in ocean waters corresponded with relatively warm climates, low levels of atmospheric iron, and reduced CO2 uptake by the oceans' plankton.
However, this latest study shows that a lack of iron at the ocean surface can limit the effect of other key elements in helping plankton take up carbon.
Dr Laetitia Pichevin, of the University of Edinburgh's School of GeoSciences said that iron is known to be a key nutrient for plankton, but we were surprised by the many ways in which iron affects the CO2 given off by the oceans.
He further suggested that if warming climates lower iron levels at the sea surface, as occurred in the past, this is bad news for the environment.
The findings are the first to pinpoint the complex link between iron and other key marine elements involved in regulating atmospheric CO2 by the oceans. Their findings were verified with a global calculation for all oceans.
The study, published in Nature Geoscience.