Narrator: There’s a new class of chemical compounds
impacting the Earth's ozone layer and raising concerns among some scientists,
but a new NASA analysis indicates
stratospheric ozone could actually be impacted more by
climate change and the continued release of already-banned chemicals.
The Earth’s ozone hole is showing signs of recovery,
decades after the landmark agreement called the Montreal Protocol
that banned many chemical compounds harmful to the ozone layer.
Liang: So we know the Montreal Protocol was a huge success.
This was signed in the late 1980s when scientists and policy makers
from around the world gathered together to try to save the ozone layer.
Strahan: The chemicals they regulated persist in the atmosphere
for many decades, they thinned the ozone layer and created a seasonal hole over Antarctica.
They basically take away part of our planet’s natural sunscreen,
and that increases the risk of skin cancer and damage to plants.
Narrator:Scientists have projected the ozone hole could disappear almost completely
by about 2075, but several factors could delay that recovery.
Liang: There are some industrial compounds that were not banned
by the Montreal Protocol, but as they enter the atmosphere, they will also
hurt the ozone layer.
Strahan: But the unregulated compounds have a short lifespan in the atmosphere
than the chlorofluorocarbons that were originally banned, so they have a short-lived impact on ozone,
and we don’t think they’ll delay recovery by more than a few years.
Liang: We projected by 2050 more than
half of ozone-destroying compounds in the atmosphere will come from
long-lived substances banned by the Protocol.
Narrator:Because these compounds stay in the air for such a long time compared to the
unregulated short-lived compounds, they will have a disproportionate and lingering
impact on ozone, so any non-compliance with the Protocol
can have significant consequences.
Strahan: And the really big uncertainty in ozone-layer recovery is climate change.
There are many naturally produced ozone-depleting substances that are emitted by the oceans,
and as the oceans continue to warm due to climate change,
those emissions will increase, and that will further delay ozone recovery.
Narrator:Scientists want to better understand how climate change will affect ozone recovery.
Liang: This is a hard problem.
As a scientific community we need to work on this major issue.
We now have a powerful new tool to simulate atmosphere and its interaction
with land and ocean, to study this issue. And that’s what we’re going to do.
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