Title: On science informing international policy:  Are emissions of a banned ozone-depleting substance really increasing?

Abstract: Ongoing global-scale measurements of long-lived gases provide unique information for addressing important science and policy-relevant questions.  As a recent example, results suggest that some entities may no longer be adhering to global controls on an ozone-depleting gas agreed to in the Montreal Protocol.  The observational evidence is straightforward: the concentration of CFC-11, the second most abundant ozone-depleting gas, is no longer decreasing as fast as it was 5 years ago, and the slowdown started first in the northern hemisphere.  These changes typically indicate increasing emissions, but this unsettling conclusion seemed highly unlikely, given that production of CFC-11 has reportedly been banned for nearly a decade.  Equally implausible, however, was the alternative conclusion:  that global atmospheric chemistry or dynamics had changed and altered the atmospheric decline of CFC-11.  In this talk I’ll present and update the scientific evidence supporting the assertion that CFC-11 emissions and production have increased in recent years.  I’ll also briefly describe the international response to this news, which is encompassed by a decision adopted earlier this month by the international community tasked with ensuring recovery of the ozone layer, the Parties to the Montreal Protocol.

Speaker Information


Steve Montzka


Research Chemist


NOAA Earth System Research Laboratory


Global Monitoring Division


Eric Saltzman

Date and Time: 

Friday, November 30, 2018 - 3:00pm


The Jenkins Room | Croul Hall 3101