Long-Lived Clam Yields Valuable Historic Data

Researchers from Cardiff University are learning about the history of the ocean from the longest-living animal on Earth: the quahog.

You might remember the headlines from a few years ago when scientists discovered Ming, a 507-year-old quahog who was named for the Chinese dynasty in power when the animal was born. Like other bivalves, quahogs have growth rings that can be used to determine the animal’s age and learn a little about their histories. Given that quahogs can live for 500+ years, researchers can learn a lot about the history of their native habitat in the North Atlantic Ocean by studying the chemistry of the growth rings of these particular animals.

“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,” explained lead author Dr David Reynolds, from the School of Earth and Ocean Sciences.

This pattern switched during the industrial period (1800-2000). Changes in the North Atlantic happened along with or after changes in the atmosphere, which could be due to the influence of greenhouse gasses.

Instrumental records of the oceans only span about 100 years and other methods of study (like sediment cores) that take us further back in time come with their own set of complications and uncertainties.

“Our results highlight the challenge of basing our understanding of the climate system on generally short observational records,” said study co-author Professor Ian Hall. “Whilst they likely capture an element of natural variability, the strong anthropogenic trends observed over recent decades likely masks the true natural rhythms of the climate system. These data therefore provides an invaluable archive of the natural state of the ocean system and the expression of anthropogenic change over the last 1000 years.

“If we are to continue to develop the most robust near-term predictions of future climate change we must continue to develop robust reconstructions of past ocean variability.”

This article appears courtesy of Marine Science Today and may be found in its original edition here.