In 1985, a group of scientists sounded the alarm that the ozone layer was rapidly thinning. They warned that if nothing was done, it could result in massive environmental damage. Thankfully, their warning was heard, and a concerted effort was made to repair the damage. 

How it began

The hole in the ozone layer was first discovered in 1985 by a group of British scientists. They found that the amount of ozone in the atmosphere was decreasing at an alarming rate and that if nothing was done to stop it, the hole would continue to grow, rendering disruptive consequences to humankind and our environment at large. 

Understanding the problem

Ozone is a gas that sits in the Earth’s stratosphere, a layer of the atmosphere 10-50 km above the Earth’s surface and protects us from the sun’s harmful ultraviolet (UV) rays. Without it, there are many potential dangers to our health and our environment; from skin cancer and certain eye diseases to permanent damage to plant life, which can disrupt entire ecosystems. 

When exposed to intense UV Light, some compounds release chlorine or bromine into the stratosphere. These compounds contribute to ozone depletion and are therefore called ozone-depleting substances (ODS). To put it into perspective, 1 chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere. Ozone can therefore be destroyed at a faster rate than it is naturally created. 

ODS that release chlorine include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), carbon tetrachloride, and methyl chloroform. ODS that release bromine include halons and methyl bromide. Although ODS are emitted at the Earth’s surface, they are eventually carried into the stratosphere in a process that can take as long as two to five years. 

However, not all chlorine and bromine sources contribute to ozone layer depletion. Researchers have found that chlorine from swimming pools, industrial plants, sea salt, and volcanoes does not reach the stratosphere. 

The Montreal Protocol

 In 1987, the Montreal Protocol was initially signed by 46 countries but now has almost 200 signatories. This treaty banned the use of chlorofluorocarbons (CFCs), a human-made compound which was found to be responsible for the depletion of the ozone layer. This resulted in a significant reduction in the consumption of ODS. 

The extent of the ozone hole is strongly driven by stratospheric temperature, with warmer temperatures leading to a smaller ozone hole, such as in 2019 when the hole was recorded the smallest in size since the 80’s. The hole however continues to fluctuate in size annually, usually reaching its largest area during the coldest months in the southern hemisphere, from late September to early October. 

Altogether, the ozone hole has shown signs of healing since 2000, which is predominantly a result of phasing out ODS. From 30.31 million sq km in 2000, to 24,8 million sq km in 2021, we are set on a good trajectory for the 21st century. 


Montreal Protocol signatories


Decrease in size since 2000

2019 has presented the best year yet, with the size of the hole equating to 10 mil sq km.

A positive perspective for the better

As the ozone layer began to heal, the Montreal Protocol proved to be a success story and often cited as one of the most successful environmental treaties ever signed. It is a perfect example of what can be achieved when the international community comes together to solve a problem. The Montreal Protocol shows us that it is possible to repair the damage we have done to the environment – but only if we act quickly, decisively, and collectively. 

Overall, the mitigation of ozone depletion is still a very delicate subject and scientific evidence suggests that more action is still required to remove pressure on the ozone layer caused by ODS. 

We find the story of the depletion of the ozone layer in its entirety, a hopeful one. It shows us that by collectively choosing to do better we can achieve the desired outcome if we are relentlessly committed to a cause. 

We hope that this story will inspire you to take action in your own community to make a difference for our people, our planet, and its resources. 

We can always #dobetter.