Ozone hole could slightly warm Earth
A new computer-modelling study has suggested that the ozone hole could actually have a slight warming influence, but it is only due to its effect on winds and not temperatures.
Washington: A new computer-modelling study has suggested that the ozone hole could actually have a slight warming influence, but it is only due to its effect on winds and not temperatures.
The new research suggests that shifting wind patterns caused by the ozone hole push clouds farther toward the South Pole, reducing the amount of radiation the clouds reflect and possibly causing a bit of warming rather than cooling.
Lead author Kevin Grise, a climate scientist at Lamont-Doherty Earth Observatory of Columbia University in New York City, said that they were surprised this effect happened just by shifting the jet stream and the clouds.
Grise notes this small warming effect may be important for climatologists trying to predict the future of Southern Hemisphere climate.
Each ozone molecule consists of three oxygen atoms bound together. These ozone molecules gather in the lower portion of the stratosphere about 20 to 30 kilometers (12 to 19 miles) above the ground-about twice as high as commercial airliners fly.
An actual consequence of the ozone hole is its odd effect on the Southern Hemisphere polar jet stream, the fast flowing air currents encircling the South Pole.
Despite the ozone hole only appearing during the spring months, throughout each subsequent summer the high-speed jet stream swings south toward the pole.
Grise said that for some reason when you put an ozone hole in the Southern Hemisphere during springtime, you get this robust poleward shift in the jet stream during the following summer season.
He said that people have been looking at this for 10 years and there`s still no real answer of why this happens.
The team of scientists led by Grise wondered if the ozone hole`s impacts on the jet stream would have any indirect effects on the cloud cover. Using computer models, they worked out how the clouds would react to changing winds.
Grise said that because the jet stream shifts, the storm systems move along with it toward the pole and if the storm systems move, the cloud system is going to move with it.
High- and mid-level clouds, the team discovered, traveled with the shifting jet stream toward the South Pole and the Antarctic continent. Low-level cloud coverage dropped in their models throughout the Southern Ocean.
While modelling clouds is a difficult task due to the variety of factors that guide their formation and movement, Grise noted that observational evidence from the International Satellite Cloud Climatology Project, a decades-long NASA effort to map global cloud distributions, supports their theory of migrating cloud coverage.
The findings have been published in Geophysical Research Letters, a journal of the American Geophysical Union.