Clam Study Explains Oceanic Climate Change History

A 10-year study on a 1,000-year marine climate record in North Atlantic has given explanations on how the ocean is affected by climate change.

Phys.org reported that researchers from Bangor University's School of Ocean Sciences in Wales -- Alan Wanamaker (who is now in Iowa State University), Paul Butler, James Scourse and Chris Richardson -- and Cardiff University's School of Earth and Ocean Sciences in Wales -- Ian Hall and David Reynolds -- co-wrote a study using 500-year-old quahog clams from North Icelandic Shelf to determine ocean conditions over 1,000 years.

Just like how the rings in trees could tell people about their growth, the researchers were able to determine the condition of an ocean through patterns, matching growth rings and overlapping on the shells. This helped Wanamaker, who pioneered the clam study, and his co-authors create a master chronology of growth increments in the past 1,000 years.

With grants coming from the U.K.'s Natural Environment Research Council and the European Union, the researchers were able to produce a 1,000-year coverage of a dated annual record of ocean conditions and study how North Atlantic's temperature, density and circulation changes affected the changes in the atmosphere.

According to researchers, changes in ocean conditions initially triggered changes in the atmosphere and weather patterns for hundreds of years before the industrialization began in the 19th century.

This design shifted over the next 200 years when the ocean has already become the one influenced by atmospheric changes due to greenhouse emissions.

"Our results show that solar variability and volcanic eruptions play a significant role in driving variability in the oceans over the past 1000 years. Results also showed that marine variability has played an active role in driving changes to Northern Hemisphere air temperatures in the pre-industrial era," study's lead author David Reynolds explained, according to Cardiff University.

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

This study was published in the journal Nature Communications.