LPM applications

The climate change of the past have occurred cyclically in response to changes in orbital parameters. Human activities have disrupted these natural changes by changing the concentration of greenhouse gases. Climate impacts the environment in which all organisms live.

To assess the mechanisms and magnitude of climate change, researchers at theCLIMATE team are working on the reconstruction and evolution certain environmental parameters (ocean surface temperatures, salinity, pH, atmospheric temperatures, precipitation, evaporation, etc.) on different time scales (million years to century) and in different parts of the world.

To do this, they collect sedimentary archives (ocean and continental cores, geological sections). These archives contain microscopic fossils, living organisms that developed, died, were deposited with the sediment, and became fossilised. To be fossilised, the organisms must have a skeleton or shell that is preserved in the sediment. These microfossils are evidence of the environmental conditions that prevailed at the time of their development: they are biological indicators or fossil bio-indicators.

To validate their interpretations of the fossil environments, the researchers rely on a modern calibration. That is, they measure the environmental parameters in which the bioindicators live. These organisms, which are generally unicellular, are very sensitive to variations in the physico-chemical parameters of their environment and respond rapidly to any change in the environment. The relationship between the abundance of a current bioindicator and physico-chemical parameters is translated into statistical functions that can then be applied to fossil bioindicators (principle of actualism - morphological stability of species and ecological stability of species assemblages). Finally, many researchers are working on present-day bioindicators to better understand how they respond to climate change. ongoing climate change.

Since the 1980sThe emergence of increasing pollution (6 ^ème The use of plastics/microplastics in the environment (e.g. on the continent) has become a major societal issue. Microplastics (size <5 mm) are dispersed in all environments and even in some living beings. They originate from the fragmentation of macroplastics and are transported by rivers to the world ocean. There, after floating for some time, they end up being deposited and accumulating in the sediment on the bottom. Indestructible, in a few centuries or millennia, future generations will be able to find these "fossils" in the sediment - a fact that is not lost. indicators of human activity.