Australian ‘Black Summer’ Widen the Ozone Hole
Scientists at MIT have discovered that the Australian wildfires widened the ozone hole by 10 percent in 2020.
Wildfires create smoke particles that rise up into the sky, and stay there for over a year. These particles then react with other substances and cause damage to Earth’s protective ozone layer which stops intense UV radiation from getting through – thereby making it weaker.
Recently, scientists published a study in the journal Nature about the smoke created by the big Australian bushfires that happened between December 2019 and January 2020. These fires were worse than any other in Australia’s history, burning huge amounts of land and releasing more than 1 million tons of smoke into our atmosphere.
Researchers at MIT have discovered that smoke from the Australian wildfires caused a decrease in ozone, which is a gas found high up in the atmosphere. This reduction was estimated to be around 3-5 percent in the areas above Australia, New Zealand, Africa, and South America.
Researchers created a model which shows how the Australian wildfires had an effect on the ozone hole over Antarctica. The smoke particles from those fires stretched out the size of the Antarctic ozone hole by 2.5 million square kilometers – that’s 10% more than before it happened in 2020.
The UN recently said that the ozone layer is gradually fixing itself, because of people stopping to use ozone-destroying chemicals. But an MIT study showed that massive fires can cause a short-term drop in the ozone layer if these dangerous chemicals are still around in the air. So it’s not clear how bad wildfires will be for ozone level recovery yet.
Susan Solomon, a professor at MIT and famous climate scientist, is saying that the Australian wildfires of 2020 could be a wake-up call. She continued that these fires were not factored into the predictions about how ozone recovery would work. We have to consider if the planet gets warmer with time, will these fires become stronger and more frequent too?
This study is led by Solomon and Kane Stone, who work at MIT. People from four different scientific organizations are also helping with the research – The Institute for Environmental and Climate Research in China, the U.S. National Oceanic and Atmospheric Administration, the U.S. National Center for Atmospheric Research, and Colorado State University.
How Australian Bushfires Weakened Earth’s Protective Ozone Layer
Everyone has something special about them, whether it’s a talent, skill or physical feature. These differences should be celebrated and appreciated for their uniqueness. It is important to respect others and recognize that everyone has different abilities and interests. Acceptance and kindness can go a long way in creating an environment of harmony and understanding.
In 2022, scientists discovered that certain chemicals released by factories (CFCs) tend to interact with the smoke from wildfires. When this happens, it starts a chemical reaction resulting in chlorine monoxide—a molecule known for breaking down ozone in the atmosphere. Based on their tests, the experts concluded that Australian bushfires might have weakened the Earth’s protective ozone layer via this same process.
But Dr. Solomon noticed even more changes happening in the stratosphere—there was a lot of strange chemistry stuff with chlorine that didn’t make sense.
A team of researchers recently did a study to try and understand what molecules had changed in the sky after Australian wildfires. They looked at three different sets of data from satellites and realized that the amount of hydrochloric acid in the atmosphere had gone down while the levels of chlorine monoxide increased.
HCl (Hydrochloric acid) is found in the stratosphere. As long as it stays combined, HCl stops chlorine from destroying ozone. But if the HCl separates, chlorine can mix with oxygen to make an ozone-harming substance called chlorine monoxide.
In the coldest parts of the world, the air is so cold (155 degrees below zero!) that it can cause a chemical reaction in HCl. This was not expected to happen at places with much warmer temperatures.
This surprise reaction caused alarm as HCl levels dropped unusually low. According to Solomon, this situation “kind of felt like a warning sign”.
She wondered what would happen if hydrochloric acid (HCl) mixed with smoke particles at higher temperatures. If such a reaction was possible, it could release chlorine and break down ozone molecules. This might explain why there were so many fewer ozone molecules in the air after the Australian wildfires.
Uncovering the Link Between Wildfires and the Ozone Layer
Solomon and her team conducted research to figure out which organic molecules could react with HCl when heated, causing it to break apart.
After this, Solomon found out that HCl is able to blend in with lots of different compounds easily.
We wanted to know if the Australian wildfires had released any of the hazardous compounds that can break apart hydrogen chloride and lessen the ozone layer. When we looked at what was inside the smoke after the fires, the results were confusing.
I saw all the stuff and was so confused. I thought there was way too much to figure out. But then, I realized it had taken a few weeks before we saw the drop of HCl (hydrochloric acid), so we needed to look at the data on older wildfire particles.
The team searched even further and found that smoke particles stayed in the sky for a long time, moving around the middle part of the planet during the same times when levels of HCl went down.
According to Solomon, it is these really old smoke particles that take up most of the HCl. Amazingly, this is also happening in not-so-cold places – which is similar to what we see in the ozone hole!
The team made a chemical reaction model of Earth’s atmosphere, like how it was during those devastating Australian wildfires. What they found was that the ozone levels dropped by 5% throughout the middle latitudes and the ozone hole near Antarctica widened or got bigger by 10%.
Wildfires probably cause a decrease in ozone by reacting with hydrochloric acid. However, there may be other substances with chlorine high up in the atmosphere that wild fires could activate.
Solomon says that we have to be careful and use our time wisely. We need to make sure these chlorine-containing compounds are gone before climate change makes more fire happen. This means we should take global warming seriously and do something to get rid of these scary compounds.
This research was created by Susan Solomon, Kane Stone, Pengfei Yu, D. M. Murphy, Doug Kinnison, A. R. Ravishankara and Peidong Wang in March 2023 and published in Nature magazine. It was supported by money from NASA and the U.S National Science Foundation to study how fires affect the ozone layer.
