IPCC confirms HFO GWPs are less than 1

The Intergovernmental Panel on Climate Change (IPCC) has confirmed that both R1234yf and R1234ze(E) have global warming potentials below that of carbon dioxide.
The Intergovernmental Panel on Climate Change (IPCC), has confirmed that both R1234yf and R1234ze(E) have global warming potentials (GWP) below that of carbon dioxide.

In its latest hefty tome, Climate Change 2013: the Physical Science Basis, the IPCC lists the new HFO R1234yf as having a 20-year GWP of 1 and a 100-year GWP of less than 1.
R1234ze(E) is listed as having a 20-year GWP of 4 but, a 100-year GWP of less than 1.

That study was the first to calculate the GWPs of all fluorocarbon-based refrigerants using all available atmospheric data, taking into account local atmospheric patterns. CO2 is considered the baseline with a GWP equal to 1. Earlier studies had calculated the GWP for R1234yf at 4.