Threat to Oceans from Climate Change Must Be Key to Paris Talks, Say Scientists

Major study of plankton shows warmer seas could have a huge impact on the marine food chain

The dangers posed by global warming to the world’s oceans must be a key part of any future international climate change agreement, a group of marine research scientists are insisting, as up to now the role of the planet’s biggest ecosystem has been largely ignored at the long-running UN climate talks.

The scientists are attached to the French research vessel Tara, which is completing a three-and-a-half year trip gathering information from across the globe for the world’s largest ever study of plankton.  They plan to make their appeal at the crunch UN climate change conference in Paris this December.

Among their discoveries have been many thousands of new species of plankton, by sampling seas at a depth of up to about 500 meters in oceans from the poles to the tropics, east to west, and using DNA analysis on the 35,000 samples.  The next step will be to study the samples more closely using powerful microscopes.

“Above 90% of what we found were new [to science] and we don’t yet know what they are. What we need to do in the future is to try to understand what they are,” explained Chris Bowler, one of the scientists leading the expedition.  Plankton represents about 95% of the biomass in the oceans, and is vital in the marine food chain, but much of what makes up this soup of microscopic organisms is still a mystery.  One of the surprises for the team was that the greatest diversity they found among the specimens was in the middle-sized creatures.

Another of the key findings has been how great an effect the marine temperature has on the organisms under study.  “Temperature shapes which species are present, which is very relevant in the context of climate change,” said Bowler.

The planet’s oceans act as enormous carbon and heat sinks, playing an important role by absorbing carbon dioxide from the atmosphere – which is slowly turning the saltwater from alkaline to acidic, with severe implications for marine life – and churning heat out of the atmosphere in a long-term cycle that runs over decades.

For the ocean ecosystems, the warming we are inducing could be a huge change, said Eric Karsenti, director of Tara Oceans, a French environmental NGO.  One of the discoveries that struck the researchers was how interconnected the organisms they found were.  “Only 20% of the organisms exclude each other,” Karsenti said.  The rest are tied in a complex web of prey/predator, parasitic and mutually dependent relationships.  That means that disruptions in one part of the ecosystem could have vast repercussions across the food chain.

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