University of Toronto researchers have identified the role of climate change on ozone distribution and atmospheric circulation over the earth’s surface.
According to Michaela Hegglin, a postdoctoral fellow and lead researcher on the project, and professor Theodore Shepherd from the department of physics at U of T, UV radiation will decrease in the northern high latitudes by about nine per cent by the year 2100 and increase over the tropics and southern high latitudes by roughly four per cent. The southern high latitudes—mainly Antarctica—will experience the greatest jump, however, at an estimated 20 per cent, which will be most apparent in the spring and summer.
The Toronto team made their predictions using the computer-generated Canadian Middle Atmospheric Model. They published their findings in the journal Nature Geoscience last month.
Ozone distribution from the tropics to the high latitudes results from the breaking of massive atmospheric “waves” that stir the air as they move from the troposphere (the lowest atmospheric layer) into the stratosphere (the second major atmospheric layer). The exact mechanism by which these waves break remains unknown, although Hegglin’s colleagues are currently investigating it.
The change in ozone distribution tracked by Hegglin and her team began in the 1960s and will continue until the year 2095.
UV radiation acts on the skin to promote vitamin D synthesis. People living in northern high latitudes, like northern Canada, already experience above average rates of vitamin D deficiency diseases, such as rickets, osteoporosis, multiple sclerosis, and seasonal affective disorder.
A change in UV radiation will also harm phytoplankton, the foundation of the world’s marine food chains, which depend on the sun’s UV rays for survival. A decrease in UV radiation could reduce phytoplankton populations in northern lakes and oceans, consequently affecting organisms that depend on them for food. Reduced phytoplankton numbers might further exacerbate the effects of climate change, as the microscopic plants take up the greenhouse gas carbon dioxide during photosynthesis.
At the other end of Hegglin’s ozone predictions, an increase in radiation over the tropics and southern high latitudes could have drastic effects on human health and ecosystems. Too much UV radiation exposure can increase the rate of eye cataracts and skin cancer in humans. There is some evidence suggesting that these ailments also affect animals.
Hegglin noted that the increase in UV radiation most likely will not affect melting ice sheets, as it holds less energy than other forms of radiation in the sunlight spectrum.
Hegglin initially didn’t set out to study the effect of climate change and UV on the earth’s surface, although she was intrigued by other similar studies and decided to quantify these reported changes. She then used mathematical equations relating total stratospheric ozone with UV radiation on the earth’s surface. “I was astonished how large the impact was,” she said.
The changes that Hegglin and her team have predicted are imminent and irreversible. “Even if we stopped all [carbon dioxide] emissions tomorrow, [the predicted changes] would still happen. This is because of the very long lifetime of the greenhouse gases that are already in the atmosphere,” said Shepherd. According to Shepherd, the study highlights how climate change can have unexpected consequences, which should be investigated further.
This research was conducted under a program funded by the Canadian Space Agency and the Canadian Foundation for Climate and Atmospheric Sciences.
Shepherd explains that the CFCAS’s mandate is due to expire in approximately one year. Unfortunately, the government does not see a reason to renew it. Shepherd claims that as a result of the program’s closure, “Climate change research currently going on at U of T and elsewhere across the country will come to a crashing halt.”
