Arctic Ozone Hits Document Excessive – Watts Up With That?

From NASA Earth Observatory:

Ozone concentrations over the Arctic reached a record-high month-to-month common in March 2024. On account of large-scale climate methods that disturbed the higher environment all through the 2023-2024 winter, extra ozone moved into and endured within the stratosphere over the Arctic than at some other time within the satellite tv for pc document.

A group of NASA and College of Leeds scientists reported their findings in a September 2024 paper in Geophysical Analysis Letters. “Given the absence of excessive Arctic ozone because the Seventies,” the authors wrote, “the March 2024 document excessive ought to be thought of a constructive harbinger of the long run Arctic ozone layer.”

Between December 2023 and March 2024, a sequence of planetary-scale waves propagated upward by way of the environment and slowed the stratospheric jet stream that circulates across the Arctic. When that occurs, air from the mid-latitudes converges on the pole, sending ozone into the Arctic stratosphere. Along with the inflow of ozone, there was little or no of the standard ozone depletion by substances akin to chlorine, mentioned Paul Newman, chief scientist for Earth sciences at NASA’s Goddard House Flight Heart and lead writer of the research. “It was a really dynamical, energetic winter within the northern hemisphere,” he mentioned.

Extra stratospheric ozone is constructive for all times on Earth. The stratospheric ozone layer is a pure sunscreen, absorbing dangerous ultraviolet (UV) radiation. The authors calculated that from April–July 2024, the UV index was 6 to 7 p.c decrease within the Arctic and a couple of to six p.c decrease within the northern hemisphere mid-latitudes. Much less UV radiation means much less injury to plant DNA and a decrease danger of cataracts, pores and skin most cancers, and suppressed immune methods in people and animals.

The exercise in March 2024 is in sharp distinction to March 2020, when stratospheric ozone concentrations hit extraordinarily low ranges. With out disruption from higher atmospheric wave occasions, regular circumpolar winds prevented ozone from different latitudes from replenishing the Arctic stratosphere. The secure polar vortex additionally created colder-than-average situations, favorable for ozone-depleting reactions to happen.

The maps above present ozone concentrations over the Arctic for March 2020 (left) and March 2024 (proper), illustrating the massive quantity of variation potential there. The month-to-month averages have been calculated by the NASA Ozone Watch group and are based mostly on knowledge acquired by the OMPS (Ozone Mapping Profiler Suite) on the NASA-NOAA Suomi-NPP satellite tv for pc.

Not like over Antarctica, the place ozone holes type every year, the focus of ozone over the Arctic is extremely variable and topic to the “year-to-year vagaries” of tropospheric and stratospheric climate, Newman mentioned.

1979 – 2024

The sturdy wave occasions from late December 2023 by way of early March 2024 resulted within the will increase in ozone focus seen within the chart above. Ozone ranges peaked in March, as they usually do, after which remained effectively above common. Could, June, July, and August additionally set new information for month-to-month common ozone concentrations. “This actually is a rare northern summer season interval,” Newman mentioned.

As for what may have precipitated the bizarre stratospheric climate, the authors checked out quite a lot of components with out discovering a transparent reply. The impact of local weather change, for instance, is troublesome to quantify. “There is perhaps a local weather issue right here, however it’s not apparent,” mentioned Newman. With respect to bigger atmospheric patterns akin to El Niño and the Quasi-Biennial Oscillation: “Probably, however the contribution is comparatively small.”

Along with stratospheric climate, which is the first determinant of Arctic ozone ranges, the authors assume longer-term traits doubtless bumped ozone concentrations to document highs. Because the Montreal Protocol phased out manufacturing of ozone-depleting chlorofluorocarbons (CFCs) and halons in 1987, ozone ranges have been slowly recovering. As such, the excessive March 2024 ranges have been throughout the authors’ expectations: the Goddard chemistry–local weather mannequin, GEOSCCM, confirmed a 1-in-8 likelihood of a document excessive by 2025, and extra information are anticipated sooner or later. Nevertheless, as a result of CFCs persist within the environment for many years, common Arctic ozone isn’t anticipated to return to 1980 ranges till about 2045, they word.

Increased greenhouse fuel concentrations within the stratosphere additionally speed up ozone restoration. “This document was doubtless a results of decreased ozone-depleting substances and elevated greenhouse gases. In any other case, it could have been simply a excessive 12 months and never a document,” mentioned Newman. “I name this 12 months a harbinger of the long run.”

NASA Earth Observatory pictures by Michala Garrison, utilizing knowledge courtesy of NASA Ozone Watch. Story by Lindsey Doermann.

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