Climate change is warming the oceans and preventing water layers from mixing, which could upset the carbon storage capacity of microbes and plankton.
As the ocean surface warms, evidence shows that it will become more “stratified”, or confined to layers that mix less than they did in the past.
This should reduce overall ocean productivity, but so little is known about the effect on ocean microbes that the implication for carbon sequestration and global warming is less clear, said Stephen Giovannoni, professor of microbiology, Oregon State University, who led the study.
“A large portion of the carbon emitted from human activities ends up in the oceans, which with both their mass of water and biological processes act as a huge buffer against climate change. These are extremely important issues,” said Giovannoni, the journal Science reports.
The interest is growing, scientists say, because nearly half the world’s photosynthesis is contributed by microbial plankton, and the process of marine carbon production and consumption is much faster than on land.
A turnover of terrestrial plant biomass takes 15 years, they say, while marine turnover takes just six days, according to an Oregon statement.
Accordingly, researchers need to know more about these microbes, and whether their behaviour will amplify or reduce atmospheric carbon and the greenhouse effect. It could be either, Giovannoni said.
To reduce that uncertainty, Giovannoni advocates more aggressive development and implementation of marine microbial monitoring technology around the world, to add to what scientists can already learn from study of satellite images.
“Other forces, what we call the microbial carbon pump, could cause carbon to sink into the deep ocean and be segregated from the atmosphere for thousands of years,” he said.
It was only two decades ago that Oregon scientists discovered SAR11, an ocean microbe and the smallest free-living cell known but one that’s now understood to dominate life in the oceans, thrives where most other cells would die and plays a huge role in carbon cycling on Earth.
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