by Kunaal Venugopal
In the 1980s, the Antarctic “ozone hole” was discovered. The hole allowed detrimental ultraviolet radiation to reach the Earth, which was a concern for the health of the population. Furthermore, the hole caused significant changes to the atmosphere in the Southern Hemisphere. The ozone hole resulted in the stratosphere cooling, which resulted in weather patterns changing in regions of the Southern Hemisphere.
Antara Banerjee of NOAA’s Earth System Research Laboratory led a scientific study exploring the causes of the pause in the shifting of the jet stream and the other changes caused by the declining ozone. The result: the changes in the ozone layer were the primary cause of this pause. Banerjee told E&E News that “What [the researchers] showed [was] that after the year 2000, the effects of ozone recovery have actually been balancing the effects of increasing CO2, such that the position [of the jet stream] has remained approximately constant.” This balancing effect has been called a “‘tug of war.’”
In the Southern Hemisphere, the ozone recovery is of stronger prominence than greenhouse gas emissions, resulting in mitigation of the effects of climate change, contrary to the trends of the 20th and earlier 21st centuries. However, this temporary pause does not imply permanent mitigation of climate change in the region. Banerjee states that“[She expects] that by about midcentury … when the ozone hole is near to fully recovered, the jet stream will start to move poleward again, just because CO2 is continuing to increase.” This means that in the coming decades, greenhouse gas emissions will overpower the ozone recovery.
Ultimately, Banerjee agrees that climate change can be combated with enough global cooperation, but the time to do so is now.