December 27, 2016, by Tim Radford
Historic evidence of temperature change is revealed by mother-of-pearl layers in the shells of mollusc species that inhabit the ocean shallows.
LONDON, 27 December, 2016 – Scientists in the US believe they have found a new source of hard evidence about bygone climates − very hard and very bygone − in the nacreous layers in the mollusc mineral known as mother-of-pearl.
These layers provide a measure of the temperature at which they were laid down in the tropical seas, and the technique has been tested in a bivalve sample first fossilised 200 million years ago.
The research delivers another independent check on the climate record. Mercury thermometer measurements are only 300 years old – the modern thermometer was first fashioned by Daniel Gabriel Fahrenheit in 1714 – and the earliest systematic temperature records date only from 1659, and were limited to the English Midlands.