An extra-warm mass of water nicknamed ‘the Blob’ may have hurt the Pacific Ocean’s ability to capture climate-polluting greenhouse gas emissions, says a new study led by the University of British Columbia.
The ocean heat wave stretched more than 3,200 kilometres off the coast of North America between its first detection in 2013 and its dissipation in 2016.
Researchers at UBC now believe it may have temporarily dampened the Pacific’s “biological pump,” which shuttles carbon from the surface ocean into its depths, where it’s stored for thousands of years.
“The ocean is a huge global reservoir for atmospheric carbon dioxide,” Colleen Kellogg, a research scientist at the Hakai Institute and study co-author, explained in a UBC news release.
“If marine heatwaves reduce the capacity for carbon dioxide to be absorbed into the ocean, then this shrinks this reservoir and leaves more of this greenhouse gas in the atmosphere.”
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The research, published last week in Nature Communications Biology, suggests abrupt changes in ocean temperature affect more than just large marine life, but also the phytoplankton whose larger cells impact the ocean’s ability to act as a carbon sink.
The large-scale study was conducted by Canadian researchers, European researchers and the U.S. Department of Energy Joint Genome Institute.
The team examined seven years of DNA sequencing and oceanographic measurements from a buoy to chart how microbes and their communities were structured before the Blob — the most severe marine heat wave in recent history.
Microbes are the base of the marine food web, said UBC’s release, and understanding their response to heat waves can provide a “vital sign” for how the rest of the food chain is or will be impacted.
During the blob, researchers found an increase in microbes that were specialized to survive in environments with fewer nutrients. That’s likely due to changes in the composition of the region’s phytoplankton, which contribute to the formation of particles that impact the ocean’s biological pump.
“Marine heatwaves are one of the big challenges of climate change,” said Sachia Traving, the study’s lead author at the University of Southern Denmark.
“Knowing how they affect microbes – some of the smallest but most abundant organisms on earth – will help us understand how heatwaves will impact life in our future oceans.”
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