Tracking India’s consumption of ozone-depleting substances Key words: Montreal Protocol, climate change, India, halocarbons, ozone-depletion, CFC, HCFC, HFC

The Montreal Protocol was introduced to regulate and reduce emissions of chlorofluorocarbons (CFCs) which, along with other man-made (anthropogenic) chemicals, are known to destroy stratospheric ozone (O3). The stratosphere is a layer of the atmosphere ~12- 50 km above the Earth’s surface. Under the Montreal Protocol, all 195 countries agreed to freeze, reduce and ultimately cease the production and consumption of CFCs through a series of step changes. Crucially, it was recognised that developed countries such as the UK had been using these chemicals for longer and had the financial means to reduce their emissions at a greater rate, than developing countries such as India. Hence, developing countries were given longer to reduce their CFC emissions.

Since CFCs were used across a wide range of applications, from coolants in refrigerators, to propellants in aerosol and foam blowing agents, they required immediate replacement. Hydrochlorofluorocarbons (HCFCs) were introduced as interim replacements for CFCs. Since HCFCs contain a hydrogen atom, they are more susceptible to reaction with the hydroxyl free radical (OH) in the troposphere. Hence, their ability to destroy ozone in the stratosphere is reduced relative to CFCs. In 1990, hydrofluorocarbons (HFCs) were introduced to replace both CFCs and HCFCs. Since they do not contain chlorine, HFCs have ozone-depletion potentials of zero. However, they are potent greenhouse gases, able to warm the atmosphere many thousands of times more effectively than carbon dioxide.

Figure 1: Common examples of CFCs, HCFCs and HFCs

Estimates of CFC, HCFC and HFC emissions from developing countries are important for improving our understanding of global trends. Owing to its rapidly expanding economy and large population, India’s emissions of these gases are of importance. While a ban on CFCs came into effect in 2010, India’s emissions of these gases are likely to persist for several decades in the form of ‘banks’, such as old refrigerators and rigid foams, that continue to emit CFC for many years after installation. In contrast, India is not required to eliminate the use of HCFCs until 2030, with its timeline for a phase-down of HFCs longer still. In the absence of detailed emissions information from the Indian government, we can use atmospheric measurements to help India track its progress under the Montreal Protocol.

Aircraft measurements

Given India’s size, aircraft offer potentially the best means by which to make atmospheric measurements of anthropogenic halocarbons. The FAAM (Facility for Airborne Atmospheric Measurements) research aircraft provides a platform for the collection of ‘whole air samples’ – 3 litre stainless steel flasks that are filled with air whilst flying over India. These flasks are then returned to the University of Bristol for analysis via the Medusa GCMS analytical system. This instrument is capable of measuring gases present at very low concentrations – down to parts-per-

trillion (ppt) levels. By analysing variability in the concentration of these halocarbons with respect to the background level (i.e. the concentration of each gas already present in the atmosphere), we can say something about India’s emissions.

In the figure below, we compare variability in the mole fraction (ppt) of CFC-11, HCFC-22 and HFC-134a, all of which were/are used extensively as coolants for refrigeration and air-conditioning applications. Based on the lack of mole fraction variability, our measurements suggest that India’s CFC-11 emissions are small, which is consistent with its commitment to cease CFC production and consumption by 2010. Conversely, we see very large enhancements (relative to the baseline) for both HCFC-22 and HFC-134a, gases used predominantly as coolants in stationary air-conditioning units. Since we see considerable variability in the mole fraction of both gases, we can reasonably conclude that in 2016 (when the flasks were collected) India was at a mid-point in terms of replacing HCFC consuming units with non-ozone depleting (HFC) alternatives.

Figure 2 Sample profiles of air over India and their HCFC, CFC and HFC concentrations

India’s demand for (and emissions of) refrigerants such as HCFCs and HFCs is expected to grow exponentially over the next decade. Long-term atmospheric measurements are therefore required, to

independently track the expected increase in emissions and provide a basis for future emissions reduction legislation.

Dr Daniel Say is a postdoctoral research assistant working within the Atmospheric Chemistry Research Group (ACRG) at the University of Bristol. Dan’s work focusses predominantly on the measurement of hydrofluorocarbons, and explores the use of inverse modelling techniques for the estimation of regional emissions. He is currently using these techniques to provide the first atmospheric-based estimates of India’s CFC, HCFC and HFC emissions.

Tracking India’s consumption of ozone-depleting substances

Questions

1. What is a halocarbon? [1 mark]2. What is a GCMS? [1 mark]3. Why are HFCs damaging to the atmosphere even though they don’t destroy stratospheric

ozone? [1 mark]4. Why can CFC-11, HCFC-22 and HFC-134a, be used extensively as coolants for refrigeration?

What property(ies) are they making using? [2 marks]5. What reason is given for the expected increase in refrigerants going in to the atmosphere for

the next few decades? [1 mark]6. In figure 2 what is the background level of HFC-134a? [1 mark]7. In figure 2 what is the value of the HCFC-22 concentration above background for sample 98?

[2 marks]8. Using IUPAC nomenclature name all 3 molecules in figure 1. [3 marks]

Extension question

Explain in your own words why it is necessary to monitor the CFC, HCFC and HFC emissions of counties such as India. [5 marks]

Tracking India’s consumption of ozone-depleting substances Questions

1. What is a halocarbon? [1 mark]

2. What is a GCMS? [1 mark]

3. Why are HFCs damaging to the atmosphere even though they don’t destroy stratospheric ozone? [1 mark]

4. Why can CFC-11, HCFC-22 and HFC-134a, be used extensively as coolants for refrigeration? What property(ies) are they making using? [2 marks]

5. What reason is given for the expected increase in refrigerants going in to the atmosphere for the next few decades? [1 mark]

6. In figure 2 what is the background level of HFC-134a? [1 mark]

7. In figure 2 what is the value of the HCFC-22 concentration above background for sample 98?[2 marks]

8. Using IUPAC nomenclature name all 3 molecules in figure 1. [3 marks]

Extension question

Explain in your own words why it is necessary to monitor the CFC, HCFC and HFC emissions of counties such as India. [5 marks]