Abstract
Hydrofluorocarbons (HFCs) have been increasingly produced and used in applications such as refrigeration, air-conditioning, and foam blowing following the phasedown of ozone-depleting substances (ODSs). In addition to emissions resulting
from these uses, some HFCs, particularly HFC-23, are released
as by-products during the manufacture of other compounds.
While being benign for the stratospheric ozone layer and generally having lower radiative efficiencies than the most abundant
ODSs, long-lived HFCs are potent greenhouse gases. Therefore,
HFCs were included in the basket of substances controlled by
the 1997 Kyoto Protocol under the United Nations Framework
Convention on Climate Change (UNFCCC). Subsequently, certain HFCs were brought into the Montreal Protocol framework
by the Kigali Amendment in 2016. The Kigali Amendment, which
came into force in January 2019 for parties who ratified the
Amendment, seeks to limit the production and consumption of
a selection of HFCs. For HFC-23, the Kigali Amendment seeks to
limit emissions formed as a by-product of HCFC (hydrochlorofluorocarbon) and HFC production to the extent practicable using
approved technologies.
For the most abundant HFCs (HFC-134a, HFC-23, HFC-32,
HFC-125, and HFC-143a) and some of the less abundant HFCs,
atmospheric observations have been available for several years
or decades. Observations in the remote atmosphere can be used
to derive “top-down” global emissions. These emissions can be
compared to the sum of “bottom-up” estimates derived from accounting methods for Annex I parties to the UNFCCC, who are
required to report their emissions annually. For some parts of the
world, atmospheric observations exist in sufficient density to derive top-down emissions estimates at regional scales. These can
be compared to bottom-up estimates reported by the countries
in these regions.
Based on the historical emissions trends derived from atmospheric data and estimates of future consumption, projections of
future emissions can be derived under different policy scenarios.
These emissions scenarios can be used to estimate the climate
impact of various HFC policies in terms of future radiative forcing
and temperature change.
from these uses, some HFCs, particularly HFC-23, are released
as by-products during the manufacture of other compounds.
While being benign for the stratospheric ozone layer and generally having lower radiative efficiencies than the most abundant
ODSs, long-lived HFCs are potent greenhouse gases. Therefore,
HFCs were included in the basket of substances controlled by
the 1997 Kyoto Protocol under the United Nations Framework
Convention on Climate Change (UNFCCC). Subsequently, certain HFCs were brought into the Montreal Protocol framework
by the Kigali Amendment in 2016. The Kigali Amendment, which
came into force in January 2019 for parties who ratified the
Amendment, seeks to limit the production and consumption of
a selection of HFCs. For HFC-23, the Kigali Amendment seeks to
limit emissions formed as a by-product of HCFC (hydrochlorofluorocarbon) and HFC production to the extent practicable using
approved technologies.
For the most abundant HFCs (HFC-134a, HFC-23, HFC-32,
HFC-125, and HFC-143a) and some of the less abundant HFCs,
atmospheric observations have been available for several years
or decades. Observations in the remote atmosphere can be used
to derive “top-down” global emissions. These emissions can be
compared to the sum of “bottom-up” estimates derived from accounting methods for Annex I parties to the UNFCCC, who are
required to report their emissions annually. For some parts of the
world, atmospheric observations exist in sufficient density to derive top-down emissions estimates at regional scales. These can
be compared to bottom-up estimates reported by the countries
in these regions.
Based on the historical emissions trends derived from atmospheric data and estimates of future consumption, projections of
future emissions can be derived under different policy scenarios.
These emissions scenarios can be used to estimate the climate
impact of various HFC policies in terms of future radiative forcing
and temperature change.
| Original language | English |
|---|---|
| Title of host publication | SCIENTIFIC ASSESSMENT OF OZONE DEPLETION 2022 |
| Place of Publication | Geneva |
| Publisher | World Meteorological Organization |
| Chapter | 2 |
| Pages | 119-151 |
| Volume | 278 |
| ISBN (Print) | 978-9914-733-97-6 |
| Publication status | Published - 30 Dec 2022 |
