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Climate, Water and carbon cycles : terrestrial records across a hierarchy of time scales


IPGP - Campus Jussieu


Séminaires généraux de l’IPGP

Salle Bleue


University of Ottawa, Canada

Résumé: The observed temperature increase of ~ 0.6ºC over the last century has been attributed (IPCC) by ~ 2/3 to greenhouse gases (GHG) and ~ 1/3 to an increase in solar irradiance (TSI). Such relative attribution reflected the general consensus that no credible amplifier to muted changes in TSI was known. Recently, however, a spate of empirical observations demonstrates that sun-climate connections are apparent in a plethora of high-fidelity climate indicators, suggesting that ?solar influence on climate is greater than would be anticipated from radiative forcing estimates? (Hadley Centre technical note 62). The most likely amplification candidates are high-energy particles such as cosmic rays and solar protons, via their potential role in cloud formation. Juxtaposition of empirical records of paleoclimate with proxies for atmosphericCO2levels vs. celestial (solar and cosmic rays) intensities, across a 108 ? 101 hierarchy of time scales, indeed favours a reversal of the relative impact of the above climate ?drivers?, the last few decades being the focal point of the ongoing controversy. In the above scenario, the celestially modulated planetary energy balance drives the hydrological cycle, with the carbon cycle ?piggy-backing? on the water cycle ?thermostat?. -------------------------------------------------------------------------------- Séminaires généraux de l'Institut de Physique du Globe de Paris --------------------------------------------------------------------------------