Washington: A new research has found that climate changes from millions of years ago are recorded at daily rate in ancient sea shells.
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.
Researchers from the Department of Earth Sciences at the University of Cambridge have measured traces of magnesium in the shells of plankton using an X-ray microscope in Berkeley, California, at the "Advanced Light Source" synchrotron - a huge particle accelerator that generates X-rays to study matter in minuscule detail.
The powerful X-ray microscope has revealed narrow nanoscale bands in the plankton shell where the amount of magnesium is very slightly higher, at length scales as small as one hundredth that of a human hair.
They are growth bands, rather like tree rings, but in plankton the bands occur daily or so, rather than yearly.
Professor Simon Redfern, one of the experimenters on the project, said that these growth bands in plankton show the day by day variations in magnesium in the shell at a 30 nanometre length scale.
He said that for slow-growing plankton it opens the way to seeing seasonal variations in ocean temperatures or plankton growth in samples dating back tens to hundreds of millions of years.
The study has been published in the journal Earth and Planetary Sciences Letters.