Extreme weather events can exert profound impacts on society, economy and the environment. Short instrumental data limits our understanding of their mechanism and the evaluation of climate models.
The time resolution in traditional paleoclimate studies is usually in months or even longer time.It makes it impossible to reveal extreme weather events that happened at daily to hourly scales.
A research group from the Institute of Earth Environment of the Chinese Academy of Sciences (IEECAS) used land snail shells for extreme weather reconstruction. The study was published in Geochimica et Cosmochimica Acta.
The group has established several daily-hourly resolution proxies from the marine giant clam shells of Tridacna species using Confocal laser scanning microscope (CLSM) and nanoscale secondary ion mass spectroscopy (NanoSMIS).
They further applied these techniques to a terrestrial environment. They established a daily-weekly resolution land snail shell oxygen isotope (δ18Os) sequence. It could well reconstruct weather scale precipitation events in the study region.
The Catholic Fasciola snails are readily available in IEECAS and are selected for ultra-high resolution (~30 microns) δ18Os analysis. The precipitation amount and its oxygen isotope compositions were monitored at the campus of IEECAS since 2019. The researchers found that the variations of the ultra-high resolution δ18Os sequence resemble the monitored changes in precipitation. Both oxygen isotope records showed a negative trend from April 2020 to September 2020.
The six negative excursions in δ18Os matched well with six-time periods of increased precipitation in detail. There was a strong correlation between the oxygen isotope data of precipitation and snail shell for the six events. It suggests the potential for quantitative reconstruction of precipitation amount using the negative δ18Os data.
This evidence demonstrates that land snail shells are valuable and promising ultra-high-resolution archives for characterizing terrestrial pale weather. The widely distributed and well-preserved fossil snails in the loess-paleosol sequences on the Chinese Loess Plateau are of great potential in paleo extreme precipitation event reconstructions.