A NASA chief scientist thinks ‘rising levels of carbon dioxide helped further elevate Arctic ozone to a record level’. Tell that to the carbon capture promoters and other climate worriers.
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Policies to address ozone depletion, such as the 1987 international agreement of the Montreal Protocol, aim to stop the production and consumption of ozone-depleting substances in order to heal these ozone holes by 2045 and 2066 over the Arctic and Antarctic respectively, says Phys.org.
As such, since early 2000, levels of stratospheric ozone-depleting inorganic chlorine and bromine in the Arctic have declined, albeit rather slowly.
Amidst this bleak forecast, research published in Geophysical Research Letters has hinted at a brighter future to come. Dr. Paul Newman, Chief Scientist for Earth Scientists at NASA’s Goddard Space Flight Center, and colleagues identified March 2024 as a record high month for Arctic ozone since the 1970s, following a period of overall increase through winter 2023 to 2024.
Above-average ozone levels continued to persist through September 2024.
This is significant as, previously, spring has been associated with ozone depletion when high CFC levels were coincident with large, cold, rotating low-pressure meteorological systems, known as polar vortices.
The research team highlight the significance of this research as preliminary evidence that CFC levels are now declining, in order to allow the ozone layer to begin its lengthy recovery. Dr. Newman said, “Ozone is the Earth’s natural sunscreen. Increased ozone is a positive story, since it’s good for the environment and encouraging news that the global Montreal Protocol agreement is producing positive results.”
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The causal mechanism for these anomalous temperature and ozone levels in March 2024 is attributed to enhanced winter eddy heat fluxes from atmospheric Rossby waves. These waves move into the stratosphere and cause a downward motion in the polar regions, leading to warmer polar temperatures.
The waves also slow the stratospheric polar night jet stream (polar vortex) around the Arctic, leading to air from the mid-latitudes converging on the pole, transporting more ozone into the region than normal.
“Arctic ozone is controlled by direct depletion of ozone by chlorine and bromine compounds and ozone transport,” Dr. Newman explains.
“For the former scenario, the temperatures were too warm for much depletion. For the latter case, waves that propagate into the stratosphere from the troposphere move ozone into the Arctic, warm the polar region, and decelerate the polar vortex. El Niño events and Siberian snow cover have been examined as controlling processes for ozone transport, but do not appear to have a major impact.
“The stronger than normal transport seems to be caused by a random weather year with significant propagation of Rossby waves into the stratosphere. It is likely that the declining levels of oxygen depleting substances and rising levels of carbon dioxide helped further elevate Arctic ozone to a record level.”
Given that carbon dioxide levels are still projected to increase in the years to come, Dr. Newman states that is “highly likely” that more of these record ozone events will continue to occur.
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While the Arctic and Antarctic overall respond similarly to the effect of Rossby waves, those in the Arctic are much stronger and therefore, ozone levels are higher than in the southern hemisphere, which experiences more pronounced ozone holes.
“The Arctic has a much stronger source of Rossby waves propagating upward into the stratosphere (quantified by the stronger eddy heat flux). Hence, the Arctic is warmer, has a weaker vortex, and much more ozone. Because the Antarctic has a very cold vortex that can contain the reactive chlorine, we have deep ozone holes each year,” Dr. Newman states.
Full article here.
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Image credit: earthhow.com
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October 8, 2024 at 03:35AM
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