  It has been two decades since the cosmic-ray-driven electron-induced reaction
(CRE) mechanism for the formation of the ozone hole was proposed. The derived
CRE equation with stratospheric equivalent chlorine level and CR intensity as
only two variables has well reproduced all observed data of stratospheric O3
and temperatures over the past 40 years. The CRE predictions of 11-year cyclic
variations of the Antarctic O3 hole and associated stratospheric cooling are
also well confirmed. Measured altitude profiles of O3 and temperatures in the
Antarctic O3 hole provide convincing fingerprints of the CRE mechanism. A
quantitative estimate indicates that the CRE-produced Cl atoms could completely
deplete or even over-kill O3 in the CR-peak polar stratospheric region,
consistent with observed data. These results have provided strong evidence of
the CRE mechanism.
