[ad_1]
Time to stock up on the sunscreen. This year’s ozone hole has opened sooner and could last longer, scientists warn.
The annual drop in ozone in the Southern Hemisphere, caused by long-lived chemicals, partly explains why New Zealand has the highest rate of skin cancer in the world, according to Niwa.
The weather agency’s scientists, including Olaf Morgenstern, found the ozone hole is developing sooner than expected this spring. There are two likely culprits, he said: the eruption of Tongan volcano Hunga-Tonga-Hunga Ha’apai plus climate change.
The January 2022 eruption blasted “an astonishing amount of water” into the air, Morgenstern said. The extra water vapour, along with the effect of climate change in the upper atmosphere, is creating the ideal conditions for ozone depletion.
It took 18 months for the vapour to spread to Antarctica, but it is now having a noticeable effect, he added.
New Zealanders should follow the usual sun protection advice, Morgenstern said.
“People should look after themselves, wear sunblock and cover up bare skin or simply not go out when the UV is high.”
Ozone over New Zealand rapidly changes through the spring and summer. In October, ozone reaches a peak, because the protective molecule migrates south from the tropics. But the ozone hole over Antarctica takes effect shortly after that, with ozone levels reaching a minimum in December, Morgenstern said.
“Compared to the Northern Hemisphere, we always have less ozone.”
Chlorofluorocarbons (also known as CFCs) have a devastating effect on the ozone surrounding the planet, with one CFC molecule able to break down up to 100,000 ozone molecules.
In winter above Antarctica, a polar wind creates clouds that act as a platform for ozone depletion. On the icy clouds, the chlorine molecules from CFCs become “activated”, Morgenstern said.
With around 10% more water vapour in the atmosphere due to the eruption, there is a larger platform for this activation to take place.
Nasa/AP
The size and duration of the ozone hole during the summer could be increased compared to last year’s.
At this time of year, the sun starts to arrive in the northern edges of Antarctica. The light splits the activated, unstable chlorine molecules, which begin destroying ozone.
“We’re at the phase where the ozone hole is forming. We haven’t reached the full depth yet,” he said.
CFCs – which were commonly used in aerosol cans and fridges – have mostly been phased out, but the ones already released still have an effect on the atmosphere each year. Atmospheric chlorine has fallen in recent years, but the eruption put “a spanner in the works of ozone recovery”, Morgenstern said.
Robert Taylor/AP
In spring, the sun returns to Antarctica. But this kicks off the chemical reactions that deplete ozone.
Climate change is adding to this effect. Because greenhouse gases from fossil fuels and other sources create a blanket around the Earth, the atmosphere above this layer is cooling down. Water vapour is a greenhouse gas, so the eruption is supplementing this.
The effect is creating cooler and more stable conditions in the region where the polar clouds form, providing more activated chlorine.
The Antarctic ozone hole typically reaches its largest size in September or October and disappears in November or December. While scientists aren’t yet confident that the hole will be larger or last longer compared to the previous years, Morgenstern has a hunch this could be the case.
Summer UV levels for the rest of the decade could also be affected by the eruption, he added. “The elevated water vapour will be with us for the next several years.”
Our weekly email newsletter, by the Forever Project’s Olivia Wannan, rounds up the latest climate events. Sign up here.
[ad_2]