Rising global temperatures can increase carbon dioxide emissions released naturally by world's oceans, according to a University of Edinburgh study. Researchers said that this reaction could fuel further climatic changes.

For the study, researchers examined a 26,000-year-old sediment core from the Gulf of California to determine whether ocean's ability to absorb atmospheric CO2 has been altered over time.

Specifically they observed the concentrations of silicon and iron in tiny marine organisms - plankton - in the sediment core. Plankton is responsible for the absorption of CO2 from the atmosphere.

The researchers found that lower amounts of silicon and iron occurred during relatively warm climates. This chemical change reduced CO2 uptake by ocean's plankton.

Scientists were long suspicious about iron's role in enabling plankton to take up CO2. However, the latest study showed that insufficient amounts of iron hinder plankton's ability to swallow carbon.

This effect is prominently observed in the southern ocean and equatorial Pacific and coastal areas.

This is the first study to highlight the link between iron and other key marine elements associated with regulation of atmospheric CO2 by the oceans.

"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. If warming climates lower iron levels at the sea surface, as occurred in the past, this is bad news for the environment," said Doctor Laetitia Pichevin of the School of GeoSciences, who led the study, in the press release.

The study is published in Nature Geoscience.

Earlier this year, the UN Intergovernmental Panel on Climate Change (IPCC) said that the "irreversible" effects of global warming will be experienced everywhere, triggering food shortages and natural disasters like flooding, rising sea level and melting of ice caps.

"We live in an era of man-made climate change," said Vicente Barros, Co-Chair of Working Group II, in a statement. "In many cases, we are not prepared for the climate-related risks that we already face. Investments in better preparation can pay dividends both for the present and for the future."

On the other hand, United Nations World Meteorological Organisation (WMO) showed that atmospheric increase of carbon dioxide rose sharply in the past twelve months than in the previous decade.