Climate Change Impacts Ocean's Chemical Cycles as Temperatures Rise

First Posted: Sep 09, 2013 09:08 AM EDT

Climate change is affecting ecosystems all across the globe. Now, scientists have discovered that as conditions change, rising ocean temperatures will upset natural cycles of carbon dioxide, nitrogen and phosphorous in the world's oceans. This could have major implications for the Earth's chemical cycles, which are crucial to the regulation of various natural systems.

As ocean temperatures warm, the conditions are impacting plankton. While these creatures are tiny, they play a huge role in nutrient cycling. These creatures remove about half of all CO2 from the atmosphere during photosynthesis and then store it deep under the sea. This isolates the CO2 from the atmosphere for centuries.

"Phytoplankton, including micro-algae, are responsible for half of the carbon dioxide that is naturally removed from the atmosphere," said Thomas Mock, one of the researchers, in a news release. "As well as being vital to climate control, it also creates enough oxygen for every other breath we take, and forms the base of the food chain for fisheries so it is incredibly important for food security."

In order to see how changing conditions might affect phytoplankton, the researchers developed computer generated models. These models encompassed a global ecosystem that took into account the world ocean temperatures, 1.5 million plankton DNA sequences taken from samples and biochemical data.

"We found that temperature plays a critical role in driving the cycling of chemicals in marine micro-algae," said Mock in a news release. "It affects these reactions as much as nutrients and light, which was not known before."

The scientists discovered that under warm temperatures, marine micro-algae did not produce as many ribosomes as under lower temperatures. Since ribosomes are rich in phosphorous, this means that there will be higher ratios of nitrogen and that, consequently, the demand for nitrogen in the oceans will increase.

"This will eventually lead to a greater prevalence of blue-green algae called cyanobacteria which fix atmospheric nitrogen," said Mock.

The findings are important for understanding how the chemical cycles in our oceans will be impacted by climate change. Because these cycles can have an enormous impact on our world, learning how they will be altered in the future is crucial for understanding how the rest of our climate will fare.

The findings are published in the journal Nature Climate Change.

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