Many of us have heard about the hole in the ozone layer over Antarctica; however, what is less notable is that periodically, the defensive ozone in the stratosphere over the Arctic is also destroyed, thinning the ozone layer there. This happened in the year 2020, during the spring season, and before that, in the spring of 2011.
Each time the ozone layer depleted, environment specialists consequently noticed climate oddities across the northern hemisphere. Those spring seasons were outstandingly warm and dry in central and northern Europe, Russia, and particularly in Siberia. In different regions, like polar areas, however, wet conditions prevailed. These weather unusualities were particularly pronounced in 2020. Switzerland was also hot and dry that spring.
Whether there is a causal connection between stratospheric ozone destruction and the observed weather anomalies is a matter of debate in climate research. The polar vortex in the stratosphere, which creates in winter and decays in spring, also plays a role. Scientists have studied the phenomenon so far and have arrived at contradictory results and conclusions.
New discoveries reveal insight into the situation, thanks to doctoral student Marina Friedel and Swiss National Science Foundation Ambizione Fellow Gabriel Chiodo. Both are members of the research group headed by Thomas Peter, Professor of Atmospheric Chemistry at ETH Zurich, and are collaborating with Princeton University and other institutions.
The specialists ran reenactments incorporating ozone exhaustion into two unique environment models to uncover a potential causal relationship. Most environment models consider essential elements rather than varieties in stratospheric ozone levels, to some extent, since this would require substantially more computing power.
However, the new calculations make it very clear: the reason for the climate abnormalities seen in the northern half of the globe in 2011 and 2020 is generally ozone depletion over the Arctic. Moreover, the simulations the researchers ran with the two models generally coincided with observational information from those two years and eight other such occasions that were used for comparison purposes. When the researchers "turned off" ozone destruction in the models, they could not reproduce those results.
"What surprised us most according to a logical perspective is that, even though the models we were utilizing for the recreation are unique, they created comparable outcomes," says co-creator Gabriel Chiodo, SNSF Ambizione Fellow at the Institute for Atmospheric and Climate Science.
Ordinarily, ozone absorbs UV radiation discharged by the sun, in this manner warming the stratosphere and assisting with separating the polar vortex in spring. However, in case there is less ozone, the stratosphere cools, and the vortex becomes stronger. "A solid polar vortex then delivers the effects seen at the Earth's surface," Chiodo says. Ozone consequently assumes a significant part in temperature and circulation changes around the North Pole.
The new discoveries could assist climate researchers in making more accurate future seasonal weather and climate forecasts. This considers better-predicting heat and temperature changes, "which is important for agriculture," Chiodo says.
Friedel adds, "It will be intriguing to notice and show the future development of the ozone layer." This is because ozone consumption proceeds, even though ozone-depleting substances like chlorofluorocarbons (CFCs) have been prohibited since 1989. CFCs are long-lived and linger in the atmosphere for 50 to 100 years; their capability to cause ozone destruction goes on for quite a long time after being removed from the flow. "However, CFC concentrations are consistently declining, and this brings up the issue of how rapidly the ozone layer is recovering and what this will mean for the environment system," she says.