USA: The new HFO alternative refrigerants have been found to have GWPs below that of carbon dioxide, according to a new study.
An independent peer-reviewed paper published in the latest issue of Reviews of Geophysics found both R1234yf and R1234ze to have GWPs less than the baseline of 1 for CO2 and substantially lower than previously thought. Until now, R1234yf had a published GWP of 4 and 1234ze 6.

The paper, Global warming potentials and radiative efficiencies of halocarbons and related compounds: A comprehensive review, found the radiative efficiencies (RE) of 49 compounds to be significantly different from those in the published in the most recent Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4). The report also presents new RE values for more than 100 gases which were not included in AR4.

The paper was produced by several leading chemists and environmental scientists from Europe and the US, is the first known study where the GWPs of all fluorocarbon-based refrigerants have been calculated consistently using all available atmospheric data, taking into account local atmospheric patterns.