THE HEALING BLANKET

 

In our schooldays, we have read, heard and learnt about various goose bumps giving facts/stories/reports related to our evolution, cosmos, technologies, history and the list goes on. Among that lot, one was about Ozone layer depletion. I clearly remember that lesson where my teacher taught us about the Ozone layer depletion, the benefits of Ozone layer and how we are degrading it and what effect is it bringing on the earth and its inhabitants.

What is Ozone layer?

The earth’s atmosphere is stratified into troposphere, stratosphere, mesosphere and exosphere. Ozone layer is present in Stratosphere. Ozone layer is a protective layer that traps Ultraviolet radiation or UV light that damages DNA molecules in plants and animals, causes sunburns, cataracts, skin cancer, and crop damages. The thickness of the ozone varies all over with thinner near the equator and thicker over the poles. Variation in the thickness is observed from season to season which is mainly because of atmospheric circulation patterns and solar intensity. The thickness of the ozone layer is measured in Dobson unit.  Ozone is very rare, according to NOAA; there are only about three molecules of ozone for every ten million molecules of air.

Depletion of the Ozone

Ozone layer gets depleted by natural causes like sun-spot activity, stratospheric winds, and volcanic eruptions. The ozone layer depletion got amplified by the anthropogenic activities. The Industrial Revolution that the world saw had an invisible hand in the depletion of the layer which left visible marks on the planet. The depletion of the ozone layer is nothing but the thinning of the Ozone layer which is brought about when Chlorine and bromine atoms in the atmosphere come in contact with the Ozone and thus destroys it.

Ozone Depleting Substances (ODS) are the compounds that release chlorine and bromine in exposure to high ultraviolet light which then contributes to its depletion. ODS includes Chlorofluorocarbon, Carbon tetrachloride, hydrochlorofluorocarbons and methyl chloroform, halons, methyl bromide and hydrobromofluorocarbons. These subsbtances are used in refrigerators, air conditioners, solvents, dry-cleaning agents, fire extinguishers, adhesives, aerosols etc.

The Montreal Protocol, 1987

The Montreal Protocol is one of the few protocols till date to get universal ratification. The protocol was adopted on 16^th September, 1987 that aims to regulate the production and consumption of almost 100 man-made chemicals or ODS. With the new developments –scientific, technical and economical, the protocol continues to be adjusted and incorporate new amendments. The funding is implemented by UN Environment Programme (UNEP), UN Development Programme (UNDP), UN Industrial Development Organisation (UNIDO) and the World Bank. Hydrochlorofluorocarbons (HCFCs), a potential ODS and Greenhouse gas, is widely used in refrigerators, air conditioning and foam applications is nearly 2000 times more potent than CO₂ in terms of global warming potential (GWP). Developed countries have agreed to reduce their consumption of HCFCs and completely phase down then by 2020. Developing countries agreed to phase out in 2013 and step-wise reduction till their complete phase out by 2030.

On 15^th October, 2016, the Parties to the Montreal Protocol met in Kigali, Rwanda and reached an agreement to phase down HFCs. Hydrofluorocarbons (HFCs) was introduced as an alternative to CFCs and HCFCs till their phase-out is complete. HFCs was widely used in AC, refrigerators, aerosols, foams etc, its uncontrolled growth started to pose a great challenge to keep the rising temperature  at or below 2⁰ C this century. HFCs do not deplete ozone layer but has high GWP in the range of 12 to 14000. Countries agreed to add HFCs to the list of controlled substances and approved a timeline for their gradual reduction by 80-85 per cent by the late 2040s. The first reductions by developed countries are expected in 2019. Developing countries will follow with a freeze of HFC consumption levels in 2024 and in 2028 for some nations.

Success Achieved

As per the UN reports, the blanket is healing, though slowly but noticeably. A scientific assessment found a progress after about 35 years of every nation’s pledge to stop producing chemicals that damages the Earth’s protective layer. To quote the reports presented at Denver, “In the upper stratosphere and in the ozone hole we see things getting better,” said Paul Newman, co-chair of the scientific assessment. The progress is slow, according to the report presented at the American Meteorological Society convention. The global average amount of ozone 18 miles (30 kilometers) high in the atmosphere won’t be back to 1980 pre-thinning levels until about 2040, the report said. And it won’t be back to normal in the Arctic until 2045. Antarctica, where it’s so thin there’s an annual giant gaping hole in the layer, won’t be fully fixed until 2066, the report said.

The two chief chemicals that munch away at ozone are in lower levels in the atmosphere, said Newman, chief Earth scientist at NASA’s Goddard Space Flight Center. Chlorine levels are down 11.5 percent since they peaked in 1993 and bromine, which is more efficient at eating ozone but is at lower levels in the air, dropped 14.5 percent since its 1999 peak, the report said. Bromine and chlorine levels “stopped growing and is coming down is a real testament to the effectiveness of the Montreal Protocol,” Newman said. A few years ago emissions of one of the banned chemicals, chlorofluorocarbon-11 (CFC-11) stopped shrinking and was rising. Rogue emissions were spotted in part of China but now have gone back down to where they are expected, Newman said.

The report also warned that efforts to artificially cool the planet by putting aerosols into the atmosphere to reflect the sunlight would thin the ozone layer by as much as 20 percent in Antarctica.

The healing of the Ozone hole is an excellent example of the continued efforts of all the stakeholders of the environment, their policy making and the behavioral change that we can bring about in our daily life. All thanks to the Montreal Protocol where our leaders took the pledge in favour of the Earth’s betterment. Such kind of collaboration, accommodative stance and innovative approach is the need of the hour.

“It is our collective and individual responsibility to preserve and tend to the world in which we all live” – Dalai Lama