Researchers could see into the past by looking at plankton shells.
A research team used a "huge X-ray microscope" to look at climate-revealing growth bands in the shells, a University of Cambridge news release reported. The process could allow researchers to track short timescale changes in the ocean's temperature that took place millions of years ago.
The growth rings can be thought of as tree rings that show how old a tree is. When the plankton dies they fall to the ocean bottom and get preserved in the muddy sediment. By harvesting these fossilized shells the team was able to look at what the ocean looked like a million years ago.
"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 [analyze] 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," the news re;ease reported.
The planktons' shells are made of mineral calcite, which traps any impurities that may be in the water. The team noticed plankton that lived in warm water had more chemical impurities trapped in their shells than those that lived in cooler areas.
The X-ray telescope allowed the researchers to look at the narrow nanoscale bands in the plankton shell where magnesium levels are slightly higher
"These growth bands in plankton show the day by day variations in magnesium in the shell at a 30 nanometre length scale. 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," Professor Simon Redfern, one of the experimenters on the project, said.
"Our X-ray data show that the trace magnesium sits inside the crystalline mineral structure of the plankton shell. That's important because it validates previous assumptions about using magnesium contents as a measure of past ocean temperature," Redfern said.
