Warming Seas Signal Bad News for the Climate: The Feedback Loops are Starting

The world’s oceans are changing. Dead zones, disappearing marine life, acidification, rising water levels and warming temperatures are all contributing to a crisis for marine ecosystems.

This summer saw the warmest ocean surface temperatures on record for July (62.5 F), surpassing the last record high in 1998, and combined average global land and ocean surface temperature that ranked fifth-warmest since global records began in 1880 according to data from the US National Oceanographic and Atmospheric Administration (NOAA).

NOAA data also showed the highest ocean surface temperature on record for June and the sixth warmest June on record for land temperatures.

For both months, ocean surface temperatures were 1.06 degrees F higher than the 20th century average. While this may seem like a small variation, it has a tremendous impact.

“Based on the physics of the oceans being such a vast reservoir for heat, small changes in ocean temperatures are massively significant for the amount of energy in the overall planetary climate system,” says Derek Arndt, Director of the Climate Monitoring Branch of NOAA's National Climatic Data Center.

“As water warms, the concentration of absorbed gases it holds decreases.”

Evidence in Marine Life

Scientists are already seeing the repercussions of climate change in the bleaching of coral reefs, says Mark Eakin of NOAA’s Coral Reef Watch. When I spoke to him, he was on his way to Papua New Guinea for a joint project with Nature Conservancy to put instruments in place to measure water temperatures and coral bleaching with the hope of finding ways to protect reefs from the effects of climate change.

Coral bleaching was first seen on a large scale in the early 1980’s, during the 1982-83 El Niño cycle. During El Niño years, tropical storms that can cool the water are more rare, and the warmer water that characterizes the El Niño phenomenon can be devastating for corals, causing them to expel the symbiotic algae that gives them their color and that they rely on for nutrients.

Eakin does not believe that the current coral bleaching is simply an El Niño phenomenon, though.

“Since the 1980s, the frequency of bleaching events has been increasing and has been related to rising sea temperatures,” Eakin said.

In addition to the temporary warming trend of El Niño is the long-term trend of climate change. "Greenhouse gases are almost certainly the major driver of the warming planetary climate system and as part of that, ocean temperature surfaces will rise too,” Arndt said.

In Australia, official with the Great Barrier Reef Marine Park Authority are worried that continued warming from climate change will kill the massive reef in the coming decades. In a report this week, they suggest that the reef, home to some 1,500 species of fish, will be in serious trouble once atmospheric CO2 concentrations rise over 400 ppm. CO2 concentrations are already close to 390 ppm and rising.

"The overall outlook for the Great Barrier Reef is poor and catastrophic damage to the ecosystem may not be averted. Ultimately, if changes in the world’s climate become too severe, no management actions will be able to climate-proof the Great Barrier Reef ecosystem," the authority writes.

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