SNOWPACE project field campaign
In February and March 2018, FARLAB water isotope instrumentation was for the first time deployed in a comprehensive field campaign. The NFR project SNOWPACE (https://www.uib.no/en/rg/meten/109877/snowpace) and the international Iceland-Greenland Seas Project provided the scientific framework for a parallel deployment of vapour isotope measurements on board of R/V Alliance and the research aircraft MASIN from the British Antarctic Survey. The ship and aircraft encountered harsh and adverse weather conditions requiring full concentration by crew and scientists. These were however the weather conditions desired by the scientific team, allowing to probe the local water cycle north of Iceland during cold-air outbreaks on extended periods. In addition to the vapour measurements, a comprehensive set of freshwater and sea water samples have been retrieved during the campaign, including surface water samples, CTD water samples, and snow samples from two transects in northern Iceland which have been analysed at FARLAB. All instruments, sample protocols and data processing worked satisfactorily, demonstrating the field-going freshwater isotope component of FARLAB is now on an operational level.
Clumped isotope paleothermometry
We are measuring clumped isotopes in foraminifera (microfossils) from marine sediments to reconstruct ocean temperatures through the Cenozoic era (the last 65 million years) within the C4T and CLIP projects. Planktic foraminifera record sea surface temperatures whereas benthic foraminifera living at the sea floor record the temperature of deep water masses. The advantage of this temperature proxy is that it is independent of other environmental variables like changes in the composition of seawater. We can therefore also use the results to reconstruct seawater 𝛿18O (in combination with 𝛿18O of calcite, obtained in the same measurement) or elemental composition changes in seawater. This way, we can find out when and how ocean temperature or the size of major ice sheets changed during major climatic events in the past.
We have tested the clumped isotope method for foraminifera with recent sediment samples from various locations and find good agreement with laboratory-based carbonate calibrations. We are in addition investigating potential alteration of the signal during burial of the microfossils in the sediments over long periods of time.
The clumped isotope method is furthermore used in stalagmites from Borneo (T-TRAC project) and South Africa (Center of Excellence SapienCE). In stalagmites, the method can not always be used directly to reconstruct temperatures, but in such cases it is a sensitive tool for detecting kinetic fraction effects during calcite precipitation when used in combination with other methods for temperature reconstruction.