However, now a «rebound effect» threatens to accelerate the rate of global warming. Hydrofluorocarbons (HFCs), which have been used in recent years in increasing quantities as substitutes for CFCs, are also climatically very active and many are also extremely long-lived. In the renowned journal «Science» an international team of researchers recommends that the most potent of these gases also be regulated. This could save the positive «side effect» of the Montreal Protocol for the global climate.
It is regarded as the most successful international environmental agreement and has, to date, been ratified by 196 countries – the Montreal Protocol on Substances That Deplete the Ozone Layer. As a result, CFCs and ozone «killers» will gradually disappear from the atmosphere over the coming decades. And because many of these substances are also very active greenhouse gases, the Earth's climate will profit from the sinking concentrations too.
So far, so good. In many processes where previously CFCs were used, these are now being increasingly substituted by fluorinated compounds such as HFCs (which, simply put, are similar substances to CFCs but do not contain chlorine and do not deplete stratospheric ozone). They are used as cooling agents in air conditioning plants and refrigerators, as propellants in aerosol cans, as solvents and as foaming agents in the manufacture of foam products. However, there is a downside to the use of HFCs – they are also very potent greenhouse gases. HFC-134a, also known as R-134a, for example, which is used in automobile air conditioning units, is 1430 more active than the «classic» greenhouse gas carbon dioxide (CO2).