|Global ozone-depleting substances (ODSs) and HFC emissions (A), global CO2 and HFC emissions (B), and ODS, HFC, and CO2 global RF (C) for the period 2000–2050. Velders et al. (2009) Click to enlarge.|
The contribution of hydrofluorocarbons (HFCs) to global warming by 2050 will be more than that of current global CO2 emissions from houses and office buildings, according to a study by team of scientists from a the Netherlands Environmental Assessment Agency (PBL), the National Oceanic and Atmospheric Administration (NOAA), DuPont Fluoroproducts, and the US Environmental Protection Agency (EPA).
These HFCs, gases used in refrigerators and air conditioners, are substitutes for ozone-depleting gases, but they are also strong greenhouse gases. Their contribution to global warming is currently small, but can increase to the equivalent of 9-19% (CO2-eq. basis) of projected global CO2 emissions in business-as-usual scenarios by 2050. This percentage increases to 28–45% compared with projected CO2 emissions in a 450-ppm CO2 stabilization scenario.
Their assessment was based on an analysis of current hydrochlorofluorocarbon (HCFC) consumption in leading applications, patterns of replacements of HCFCs by HFCs in developed countries, and gross domestic product (GDP) growth.
In a hypothetical scenario based on a global cap followed by 4% annual reductions in consumption, the researchers found that HFC radiative forcing peaks and begins to decline before 2050.
An open access paper on the research was published online 22 June in the Proceedings of the National Academy of Sciences. Lead author is Guus Velders of the Netherlands Environmental Assessment Agency.
The consumption and emissions of hydrofluorocarbons (HFCs) are projected to increase substantially in the coming decades because of increased demand for refrigeration, air conditioning and insulating foam products in developing countries in the context of the regulation of ozone depleting gases under the Montreal Protocol. The demand for HFCs in developing countries is estimated to be 800% greater than in developed countries by 2050.
We report new baseline scenarios for the consumption and emissions of HFCs to 2050 based only on existing policies. As in the SRES scenarios, the growth in demand for these compounds is based on GDP and population. However, the new scenarios incorporate more recent information such as (i) rapid observed growth in demand, substantiated by atmospheric observations, for products and equipment using HCFCs and HFCs in developing countries; (ii) reported increases in consumption of HCFCs in developing countries; (iii) replacement patterns of HCFCs by HFCs as reported in developed countries; (iv) accelerated phaseout schedules of HCFCs in developed and developing countries, and; (v) increases in reported use of HFC-134a in mobile AC in developed and developing countries. The analysis results in significantly larger emissions in 2050 than could be expected based on previous projections.—Velders et al.
The 1987 Montreal Protocol—restricting the use of ozone-depleting substances—helps both to protect the ozone layer and to reduce global warming. Without the protocol, the contribution of ozone-depleting gases to global warming would have been double that of today (currently 20% of the sum of all greenhouse gases).
The ozone layer is doing better since ozone-depleting gases (CFCs) have been replaced by alternative gases (HCFCs) in spray cans, refrigerators, and foams, on a global scale. Two years ago, the Montreal Protocol was adjusted when participating countries decided to accelerate bringing the reduction of HCFC production down to zero: before 2020 in developed countries, and before 2030 in developing countries. Alternative gases are available: the hydrofluorocarbons (HFCs). Although these gases do not contain chlorine and, therefore, do not deplete the ozone layer, they are greenhouse gases, as are their predecessors. The increasing use of HFCs could significantly undo the climate benefits attained under the Montreal Protocol.
Partly based on this research, the eight nation-states and territories of Micronesia and the Republic of Mauritius have proposed to regulate these HFCs under the Montreal Protocol, although the treaty does not cover these gases. HFCs, in fact, do not deplete the ozone layer. They are covered by the Kyoto Protocol, but are regarded as outsiders, considering their applications. The Montreal Protocol would have more expertise to control these gases.
Guus J. M. Velders, David W. Fahey, John S. Daniel, Mack McFarland, and Stephen O. Andersen (2009) The large contribution of projected HFC emissions to future climate forcing. PNAS doi: 10.1073/pnas.0902817106