Why should we care about the climate of the past?
Our climate is continuously changing and has severe impacts on society and our environment. We hear news of floods, storms and droughts almost daily. Studying our past climate helps us understand climate changes and gives scientists clues that will help us plan for future climate changes.
A great deal of climate research is focused on ensuring that climate models can simulate most aspects of the present-day climate. The study of past climate, paleoclimatology, helps scientists to improve the ability of computer models to simulate future climate.
Modern climate records from satellites and other equipment generally cover less than ~150 years. This is too short to examine the full range of climatic variability. For this reason, scientists use imprints created during past climates to interpret paleoclimate. An example is the use of fossils and other shelled organisms from foraminifera, as well as sediments in aquatic and marine environments. Once the organisms die, their shells, made from calcium carbonates, get buried in sediments on the bottom of lakes and oceans. By drilling cores into the sediment layer, scientists collect these fossils and use them to “read” past climate.
How does this work?
The stable oxygen isotope composition of the fossils can be used to infer past water temperatures. These oxygen isotopes are found naturally in both the atmosphere and dissolved in water. Warmer water tends to evaporate off more of the lighter isotopes leaving the water isotopically heavier. This means that when shells grow in warmer waters they will be enriched in the heavier isotope.
Find out more about the process in this video:
https://www.youtube.com/watch?v=oaOfeSJZ3lY
For the analysis of isotopes in (calcium) carbonates, Thermo Fisher Scientific offers dedicated instrumentation. The Thermo Scientific 253™Plus10™kV IRMS, together with the Thermo Scientific™Kiel IV™Carbonate Device, is the gold standard for carbon and oxygen isotope analysis of carbonates, producing world-class data from small foraminifera samples. With the 253 Plus IRMS and Kiel IV Carbonate Device precisions of better than 0.1 ‰ can be reached for total carbonate amounts of down to 6 µg. With this, paleoclimatologists can resolve 0.5 °C temperature changes.