• Jacob Bourne

A Dwindling Ozone Layer Could Severely Hinder Carbon Sequestration

New research revealed that the ozone layer’s protective effect on the biosphere is more robust than previously expected, and its loss could spell even more trouble for limiting planetary overheating.



Credit: Shutterstock

A Nature study led by researchers at Lancaster University and NASA showed that the ozone layer also protects plants’ ability to draw carbon out of the atmosphere. Previous studies failed to connect the dots between the importance of ozone and atmospheric carbon dioxide levels.

“We know the ozone layer is connected to climate. We know greenhouse gases affect the ozone layer. But what we’ve never done before this is connect the ozone layer to the terrestrial carbon cycle,” said lead author Paul Young, an atmospheric and climate scientist at Lancaster University in the UK.

The Montreal Protocol was adopted in 1987 by all 198 United Nations Member States to halt ozone layer depletion by regulating nearly 100 ozone-damaging substances, particularly CFSs from refrigerants and aerosols. To this day, it’s celebrated as one of the foremost environmental successes in history.

Although previous studies had attempted to measure the impact if the Montreal Protocol had not been enacted, the Nature study looked specifically at the fate of plants.

“Past world-avoided experiments have never considered the impacts of increased UV radiation on plants, and what that would mean for the plants’ ability to sequester carbon,” said Young.

Without the international treaty, modeling showed that CFSs would have continued to increase at a rate of 3% each year, resulting in significant ozone thinning by 2050. With more harmful UV radiation reaching the Earth’s surface, it’s estimated that atmospheric CO2 would be 30% higher because plants couldn’t store as much carbon in their tissue and soil. The added CO2 would subsequently warm the planet by an additional 0.85 degrees Celsius.

While the Montreal Protocol should be showcased as an example of what’s possible with swift international cooperation, there’s evidence to suggest that we shouldn’t become complacent about ozone depletion, especially in the era of visibly worsening climate change impacts.

CFCs may be under control, but other substances pose a threat to the ozone layer. Nitrous oxide, in particular, is a greenhouse gas that has about 300 times the warming potential of CO2 over a hundred-year time span. Once the nitrous oxide is done warming the planet in the troposphere, it then migrates to the stratosphere, where it causes ozone depletion. Scientists have detected nitrous oxide being released from thawing Arctic permafrost. A new PNAS study has found that the amount of nitrous oxide emitted from poorly drained agricultural soils contributes to global warming in a way that exceeds the same soil's carbon sequestration capacity.


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Climate change itself may also be fueling ozone layer depletion, and it’s something that NASA scientists are currently trying to determine. There’s evidence that warming temperatures fuel convective storm activity over the central U.S. pushing water vapor and pollutants into the stratosphere, which is where the ozone layer is located. The concern is that complex chemical reactions from the breach could cause ozone damage. Furthermore, the phenomenon may be contributing to pushing the boundary between the troposphere and stratosphere upwards by 50 to 60 meters per decade.

The Montreal Protocol may have been a success in terms of averting one aspect of human-caused environmental disaster. Still, a potentially even greater catastrophe — climate change — is itself a threat to the shielding ozone layer.


 

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