Quahog clam offers 1,000-year history of oceanic climate change

CARDIFF, Wales, Dec. 6 (UPI) -- New analysis of the world's longest-living species, the quahog clam, Mercenaria mercenaria, has offered scientists a 1,000-year chemical history of the North Atlantic Ocean.

Scientists from Cardiff University and Bangor University compiled a history of the ocean by studying the growth rings in the shells of quahog clams. By comparing their observations to different climate records -- including historic changes in solar variability, volcanic eruptions and atmospheric air temperatures -- researchers were able to study the relationship between oceanic conditions and climate change.

Their findings -- detailed in the journal Nature Communications -- suggest the planet's oceans dictated climate change for several hundred years prior to industrialization beginning in the 19th century. Prior to the 1800s, changes in the ocean precipitated changes in the atmosphere, driving new weather patterns.

Over the last 200 years, from industrialization to the present, the ocean has operated less like a catalyst and more like an imitator. Changes in the atmosphere have dictated changes in the ocean. The revelation supports the consensus that greenhouse gas emissions are transforming the atmosphere and driving climate change.

"Our results show that solar variability and volcanic eruptions play a significant role in driving variability in the oceans over the past 1000 years," David Reynolds, a professor at Cardiff's School of Earth and Ocean Sciences, said in a news release. "Results also showed that marine variability has played an active role in driving changes to Northern Hemisphere air temperatures in the pre-industrial era."

"This trend is not seen during the industrial period, where Northern Hemisphere temperature changes, driven by manmade forcings, precede variability in the marine environment," Reynolds added.