Descripción del proyecto
El campo magnético de la Tierra y la desaparición de los neandertales
El campo magnético de la Tierra ha disminuido alrededor de un 20 % a lo largo de los últimos 150 años. Dado que la Tierra está constantemente sometida a la radiación cósmica, la intensidad depende de la fuerza del campo magnético. Durante las escalas de tiempo geológicas, ha habido períodos de colapso del momento dipolar magnético y, por consiguiente, del campo magnético, lo cual puede relacionarse con cambios en la polaridad del dipolo o con simples excursiones geomagnéticas. La radiación ultravioleta puede penetrar más profundamente en la atmósfera durante estos períodos. El proyecto REVA, financiado con fondos europeos, estudiará esta ventana ultravioleta durante los fenómenos de excursiones geomagnéticas de Mono Lake y Laschamps. Dicho estudio es importante teniendo en cuenta su globalidad y las posibles implicaciones para la evolución humana (contemporánea de la desaparición de los neandertales).
Objetivo
"The Earth is constantly subjected to cosmic radiation, the intensity of which, at the level of the upper atmosphere and the Earth's surface, depends on the strength of the magnetic field (MF) surrounding our planet. Over geological timescales, there have been periods of collapse of the magnetic dipole moment, and therefore of the MF, which can be associated with changes in the polarity of the dipole or with simple geomagnetic excursions (GE). GE events (typically lasting ~1ka to ~10ka) generate an increase in cosmic bombardment in the upper atmosphere and, ultimately, through chemical effects the destruction/thinning of the ozone layer. During these periods UV radiation can penetrate deeper into the atmosphere, while it is otherwise absorbed by the ozone layer. Yet, the reality of such a UV ""window” has never been attested by natural observations, which if present during GE events in the future would have significant environmental and above all human consequences. This is plausibly foreseen in a short term as the intensity of Earth’s MF has decreased (~20%) over the past 150 years and with an accelerated rate in the last decades (> ~10 times the normal). The aim of this project is, therefore, to test the reality of a UV window during the Mono Lake-Laschamps (~ -40 ka) GE event, which by its magnitude, its globality and the possible implications for human evolution (being contemporaneous with the disappearance of the Neanderthals), is an example of a remarkable case study. Here, by measuring stable isotopic composition of sulfur (S) at high resolution (<200 years) in ice cores taken in Antarctica, we will leverage peculiar aspects of atmospheric chemistry of the S-33 isotope. In the absence of ozone, the interaction between SO2 and UV radiation, through photochemical processes, generates mass-independent (Δ) signatures. We propose to trace a possible UV ""window"" by analyzing the evolution of the observed ΔS-33 anomaly and model the extent of depletion of ozone layer."
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MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)Coordinador
75794 Paris
Francia