Sun's Activity Impacts Ozone, Regional Climate

Our warming world can be blamed on the buildup of greenhouse gases in the atmosphere, which eat away at the Earth's protective ozone, but there is another culprit for rising temperatures that is out of this world. The Sun, new research shows, impacts the polar ozone as well and potentially leads to changes in regional, not global, climate.

With the burning of fossil fuels, it's easy to pin the increase in greenhouse gases on humans, and thereby to a large extent, the rise in the average temperature of Earth. However, according to the new findings, fluctuations in the Sun's activity impact middle atmosphere ozone, providing a potential link to regional scale climate variability. Researchers are quick to point out that this climate variability is not the same as climate change. Whereas climate change is a global trend, climate variability represents year-to-year fluctuations following solar activity.

"The detected ozone variation may in part help understand the alternation of local mild and cold winter seasons, as hints have been obtained in previous research that the ozone changes in the middle atmosphere may link as far as the surface of Earth and affect, among other things, polar wind streams," Finnish Meteorological Institute researcher Dr. Pekka Verronen explained in a press release.

By looking specifically at electron activity on the Sun, the researchers found that the polar ozone is strongly affected by this activity. The electrons, similar to those behind the colorful phenomenon known as the aurora borealis, or Northern Lights, cause significant solar cycle variation in the polar mesosphere ozone.

What happens is that the Sun's energetic electrons enter our atmosphere, and become trapped in the polar regions by Earth's magnetic field. These electrons then ionize gas molecules, leading to the production of ozone-depleting catalyst gases.

According to the study, the amount of ozone at 70-80 kilometers (43-50 miles) altitude was found to vary more than 30 percent during a solar cycle, a period of approximately 11 years. The ozone variation between the extremes of the Sun's activity is so great that it is likely to impact the temperature balance of the atmosphere.

"These results are only the first step but an important one," added led author Dr. Monika Andersson, "allowing us to better understand the long-term impacts of this type of solar activity, and its role in regional climate variability."

The findings were published in the journal Nature Communications.