Ancient Tiny Creatures Reveal the Past Temperatures of Our World's Oceans

Tiny creatures are telling scientists a bit more about the temperatures of the ancient past. Plankton that drifted across the ocean before falling to the seafloor and becoming fossilized hold the potential to improve our understanding of past climates.

For many decades, deriving past temperatures from the shells of creatures that lived tens of thousands of years ago has been key to understanding past climates. However, interpreting the records has never been easy; this is why many studies have very large margins of error when they use ocean sediments as a way of establishing past temperatures. It also explains why there's a greater focus on trend rather than actual temperature.

"This research will help scientists improve the study of past climates because they will be able to look at a species of foraminifera and the core location to very quickly get a sense of how site-specific and particular proxy measure is," said Van Sebille, lead author of the new study, in a news release. "In a way it will give us a good indication of whether the creature we are looking at to get our past-temperature estimates was a bit of a globetrotter or a stay at home type."

In this latest study, the scientists used computer models and analysis on fossil shells to investigate the impact of ocean drift. In extreme cases the variation in temperature between where the fossilized shell was found and where it came from could be up to 3 degrees Celsius. In other cases, though, the variation was negligible.

So what does this mean? The scientists are now working on a tool that can easily estimate how large the impact of drift for the location is likely to be. This, in turn, will help researchers more accurately predict temperatures for past locations.

"Our results highlight the importance of the ocean currents in transporting anything that floats," said Van Sebille. "By picking apart this variation we can add another level of certainty to estimates of past temperatures, opening a door that may help us discover what future climate change may bring to our planet."

The findings are published in the journal Nature Communications.

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