<P> Reductions of up to 70 percent in the ozone column observed in the austral ( southern hemispheric ) spring over Antarctica and first reported in 1985 ( Farman et al . ) are continuing . Antarctic total column ozone in September and October have continued to be 40 -- 50 percent lower than pre-ozone - hole values since the 1990s . A gradual trend toward `` healing '' was reported in 2016 . In 2017 , NASA announced that the ozone hole was the weakest since 1988 because of warm stratospheric conditions . It is expected to recover around 2070 . </P>
<P> Reductions of up to 70 percent in the ozone column observed in the austral ( southern hemispheric ) spring over Antarctica and first reported in 1985 ( Farman et al . ) are continuing . Antarctic total column ozone in September and October have continued to be 40 -- 50 percent lower than pre-ozone - hole values since the 1990s . A gradual trend toward `` healing '' was reported in 2016 . In 2017 , NASA announced that the ozone hole was the weakest since 1988 because of warm stratospheric conditions . It is expected to recover around 2070 . </P>
where was it first discovered that the earth 's ozone layer was being depleted
where was it first discovered that the earth 's ozone layer was being depleted
in the austral ( southern hemispheric ) spring over Antarctica
in the austral ( southern hemispheric ) spring over Antarctica