Global Warming Linked to Changes in Ocean's Chemical Cycles

Adding to the list of environmental hazards associated with rising global temperatures is a shift in the ocean's natural chemical changes, a paper published in the journal Nature Climate Change showed.

A rise in ocean temperatures -- a byproduct of rising atmospheric temperatures -- will upset the ocean's cycles of carbon dioxide, nitrogen and phosphorus, the study found.

The reason, according to the researchers, has to do with the effect of water temperature on phytoplankton, the microscopic plant-like organisms found throughout the world's oceans.

Despite their small size, these small creatures, which rely on photosynthesis to reproduce and grow, play a major role in the ecosystems where they are found.

"Phytoplankton, including micro-algae, are responsible for half of the carbon dioxide that is naturally removed from the atmosphere," lead researcher Thomas Mock of the University of East Anglia said in a statement. "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."

According to the Mock, while previous studies demonstrated the changes in phytoplankton diversity and productivity due to global warming, none showed a link between warmer temperatures and the chemical cycle in the organisms.

Mock and his colleagues were able to establish this relationship through the development of computer-generated models they then used to create a global ecosystem model accounting for ocean temperatures, 1.5 million plankton DNA sequences taken from samples and biochemical data.

Based on the resulting data, the researchers made the surprising discovery that, through its influence on ribosome production, temperature affects the cycling of marine microalgae as much as nutrients and light.

"Under warmer temperatures, marine micro-algae do not seem to produce as many ribosomes as under lower temperatures," Mock said. "Ribosomes join up the building blocks of proteins in cells. They are rich in phosphorous and if they are being reduced, this will produce higher ratios of nitrogen compared to phosphorous, increasing the demand for nitrogen in the oceans."

As far as the future is concerned, Mock explains that this "will eventually lead to a greater prevalence of blue-green algae called cyanobacteria which fix atmospheric nitrogen."