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Global Warming, Fluorocarbons, Montreal Protocol 2016 – all in Kigali, Rwanda!

Posted on November 1st, 2016 by in New Materials & Applications

Global warming header image

Those who are over forty years old may remember the horrifying events of 1994 in Rwanda. In a genocidal attack the majority Huto government killed nearly one million Tutsis. It took the heavily armed Rwandan Patriotic Front (Tutsi) lead by the future president Paul Kagame to stop the carnage.  In the aftermath, an estimated two million Rwandans, mostly Hutu’s, were displaced and became refugees.

What is most devastating is that little separates the two people who have the same language, religion and culture. The tribal differences were emphasized when in 1933 Belgian colonialists introduced a national identification card that contained ethnic classification information.  That was an example of the classic divide and rule tactic often used by colonialists to instill strife among colonized nations.  That eased governing of the people and plundering their natural resources.

Over two decades later, the wounds of the genocide have begun to heal and life has improved in Rwanda. So much so that in October 2016, the 28th meeting of the Montreal Protocol was held in Kigali, capital of Rwanda.  This time climate change was the main topic for the 1,000 participants, from 197 countries, not ozone depletion.  You can read about the latter topic in an earlier post: Ozone (O3) Hole and Healing…are we there yet?

Fluorocarbon gases have evolved over the decades to the point that the ozone hole is on a path for, albeit it slow, recovery. Most fluorocarbon gases destroy the atmospheric ozone. A factor called Ozone Destruction Potential (ODP) measures the impact of different gases on ozone layer [Ref Wuebbles, D.J., Chlorocarbon emission scenarios: potential impact on stratospheric ozone, J. Geophys. Res., 88, pp1433-1443, 1983]. ODP is calculated relative to CFC-11 gas as reference substance, which has been assumed to have an ODP value of 1. A gas with an ODP>1 destroys more ozone over its atmospheric lifetime than one with a lower ODP value (Table 1).  The most recent gases are hydrofluorocarbons (HFC’s) with ODP values of zero (0).

Majority of fluorocarbon applications have been converted to HFC’s. There is, however, a second issue with fluorocarbons; they are also potent greenhouse gases. Experts have warned of increased risks of skin cancer and global warming, if consumption and atmospheric releases of fluorocarbons are not curtailed.

Global Warming Potential (GWP) is a factor that allows comparison of the global warming impacts of different gases. Specifically, it is a measure of the quantity of energy that emission of one ton of a gas will absorb over a given period of time relative to the emissions of one ton of carbon dioxide. Higher values of GWP indicate how much more a given gas warms the Earth compared to carbon dioxide. The time period usually used for GWP’s is 100 years.

Carbon dioxide is used as the reference gas thus defined to have a GWP of 1 regardless of the time period used. Carbon dioxide emissions cause increases in atmospheric concentrations of carbon dioxide that will last thousands of years. Note the large values of GWP of HFC’s in Table 1.

Table 1 Atmospheric lifetimes, global emissions, ODP, and Global Warming Potentials of some halogen source gases and HFC substitutes [Ref D. W. Fahey, M. I. Hegglin, Twenty Questions and Answers About the Ozone Layer: 2010 Update, Scientific Assessment of Ozone Depletion, World Meteorological Organ Global Ozone Res and Monitoring Project – Rep No. 52, www.esrl.noaa.gov, 2010]

global warming

a Includes both human activities (production and banks) and natural sources. Emissions are in units of kilo tons per year (1 kilo ton = 1000 metric tons = 1 giga gram = 109 grams). b Estimates are very uncertain for most species. c 100-year GWPs.

A breakthrough took place among the signatories of the Montreal Protocol in Kigali. A global agreement was reached to phase down the consumption and production of hydrofluorocarbons. This commitment requires the international community to take practical actions to achieve the goals of the 2015 Paris Agreement.  That Agreement would limit global warming to 2°C, and aim for the more ambitious target of 1.5°C.  Importantly, China, the biggest consumer of HFC’s, agreed to an early phase down; India (another big consumer and producer) decided to come down from its earlier position of 2031 to 2024-2026.

After seven years of negotiations, Parties to the Montreal Protocol arrived at an agreement, under which developed countries (US, Japan, Europe) will begin phasing down HFC’s by 2019, while the developing countries, including India, Pakistan, Iran and Iraq, will phase out at a baseline of 2024-2026 and a freeze date of 2028.  HFC’s are widely used in refrigerators, air-conditioners and aerosol sprays.  There will be an opportunity for natural refrigerants (ammonia, carbon dioxide, water and hydrocarbons) and new gases (to be developed) to replace the HFC’s.

In the 1920’s fluorinated hydrocarbon refrigerants were developed to replace the old gases. They were considered safer than the incumbent gases, ammonia, carbon dioxide etc by being nonflammable, nontoxic, colorless, and odorless.  Little did we know that the safer fluorocarbon gases would end up having a big hand towards destroying our Planet?  Nearly a century later, ironically we are going to return to the old refrigerant gases.  Famously, Jean-Baptiste Alphonse Karr, a French writer and reporter is quoted to have said “plus ça change, plus c’est la même chose“, translated as “the more things change, the more they stay the same”.


 

All opinions shared in this post are the author’s own.

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