Climate changes from millions of years ago are recorded at daily rate in ancient sea shells, new research shows.
A huge X-ray microscope has revealed growth bands in plankton shells that show how shell chemistry records the sea temperature.
The results could allow scientists to chart short timescale changes in ocean temperatures hundreds of millions of years ago.
Plankton shells show features like tree rings, recording historical climate.
It's important to understand current climate change in the light of how climate has varied in the geological past. One way to do this, for the last few thousand years, is to analyse ice from the poles. The planet's temperature and atmosphere are recorded by bubbles of ancient air trapped in polar ice cores. The oldest Antarctic ice core records date back to around 800,000 years ago.
Results just published in the journal Earth and Planetary Sciences Letters reveal how ancient climate change, pushing back hundreds of millions of years ago into deep time, is recorded by the shells of oceanic plankton.
As microbial plankton grow in ocean waters, their shells, made of the mineral calcite, trap trace amounts of chemical impurities, maybe only a few atoms in a million getting replaced by impurity atoms. Scientists have noticed that plankton growing in warmer waters contain more impurities, but it has not been clear how and why this "proxy" for temperature works.
When the plankton die, they fall to the muddy ocean floor, and can be recovered today from that muddy ocean floor sediments, which preserve the shells as they are buried. The amount of impurity, measured in fossil plankton shells, provides a record of past ocean temperature, dating back more than 100 million years ago.
Now, researchers from the Department of Earth Sciences at the University of Cambridge have measured t
|Contact: Simon Redfern|
University of Cambridge