Here is some good news I found today:
The Montreal protocol (to ban ozone-layer-destroying gas emissions) works quite well so far and also has implications for climate change:
> As reported in the 2014 Assessment, chemistry–climate models suggest that continued accumulation of ODSs in the atmosphere in the absence of the Montreal Protocol would have led to a collapse of the global ozone layer by the mid-21st century, with devastating environ-mental implications (Newman et al., 2009; Garcia et al., 2012).
> The last Assessment also reported on the additional (mostly unanticipated) benefits of ODS regulations for mitigation of global climate change.
> Specifically, it was reported that by later this century, unregulated ODS increases could have led to global surface temperature increases comparable to tem-perature increases caused by other greenhouse gases (Velders et al., 2007) and could have almost doubled changes in the hydrological cycle (precipitation minus evaporation) over the next few decades.
The newest addition, the Kigali Amendment, phases out some more gases. This also has implications:
> As discussed in Chapter 2, these new studies indicate that the an-ticipated phasedown of HFCs is expected to avoid up to 0.4 K of global mean surface warming by 2100.
(see some plots on page 34)
http://ozone.unep.org/sites/default/files/Assessment_Panel/S...