Climate change is a huge topic and often debated across the world. We continue to burn fossil fuels and ignore our charge toward human driven climate change but while our behaviour never seems to improve, something else does! For the last few decades we have been pumping chlorofluorocarbons into the atmosphere causing a hole in the ozone layer to form. Thanks largely to worldwide regulation changes and a reduction in the use of these chemicals, the hole it seems is finally starting to get smaller.
The ozone layer is the protective shield in Earth’s stratosphere. It’s about 15 to 35 kilometres above the Earth and its presence helps to protect us by absorbing harmful ultraviolet radiation. The region is mostly ozone composed of three oxygen molecules and it filters out the UV-B and UV-C radiation which can lead to skin cancer, cataracts and can even damage parents crops. The rest of the atmosphere is composed mostly of nitrogen gas (78%), oxygen (21%) and a few other gasses making up the remaining 1%.
In the late 20th century scientists found that certain chemicals like the well known chlorofluorocarbons (CFC’s) were slowly destroying the layer. This resulted in seasonal holes appearing in the ozone especially over Antarctica. In 1987, the Montreal Protocol international treaty was signed to curb the global release of CFC’s and other ozone harmful gas.
Just recently, a team of scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA) have confirmed that the hole in the ozone layer over the south pole was relatively small compared to previous years. During the month of September to October, when the ozone depletion process is at its peak, it was the 7th smallest hole since 1992. An average season sees an incredible 20 million square kilometres of ozone depletion. The teams data even suggests the layer could fully recover by 2066.
To collect the data the team uses a number of systems. A number of satellites (Aura, NOAA-20, NOAA-21 and Suomi NPP) are used to collect data from orbit. In addition they use weather balloons which are launched from the South Pole Baseline Atmospheric Observatory to directly measure ozone concentrations.
The measurements are captured as Dobson Units. One Dobson Unit is equivalent to the number of ozone molecules that would be needed to create a layer of pure ozone 0.01 millimetres thick. Of course temperature and pressure would effect this so the measurement is based on a layer at 0 degrees Celsius and 1 atmosphere (the average pressure of atmosphere at surface of Earth.) In 2024, the measurement in October 2024 was 109 Dobson Units in comparison to the lowest ever value of 92 Dobson Units in 2006.
The Montreal Protocol certainly seems to be making a difference seeing a significant and continuous decline in CFCs. This, along with an infusion of ozone from north of Antarctica have combined to reverse the depletion.
Source : Ozone Hole Continues Healing in 2024