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Evènements

Mardi 28 novembre 2017 à 11h

LATMOS site UPMC
Salle de réunion 411, tour 45-46, 4ème étage

Evidence for continued ozone layer reduction

William Ball

ETH Zürich and PMOD, Davos

Stratospheric ozone protects life from harmful ultraviolet radiation. The Montreal Protocol, enacted to prevent ozone depletion from human activity, halted declines in column-integrated ozone in the 1990s; the upper stratosphere is recovering, but lower stratospheric trends are unknown. I will present clear evidence that lower stratospheric ozone continues to decline, preventing total ozone recovery. This result contradicts expectations and, with no clear understanding of why this trend has emerged, implies that the problem of ozone depletion is not yet fully solved. The decline may impact future estimates of ozone layer recovery, the stratospheric response to climate change, radiative climate forcing, ozone exchange between the stratosphere and troposphere, and surface levels of ultraviolet radiation.