  The Multigap Resistive Plate Chambers (MRPC) are used as a timing detector in
several particle physics and cosmic ray experiments. The gas mixture of MRPC at
current experiments is a mixture containing $\rm C_2F_4H_2$ and in some cases
$\rm SF_6$. $\rm C_2F_4H_2$ and $\rm SF_6$ have a Global Warming Potential
(GWP) of 1430 and 23900 respectively, therefore they are classified as
greenhouse gases. The studies to reduce the amount of emission of the
greenhouse gas in high energy experiments are underway; the present
contribution has been performed as part of this effort. The results have been
obtained from the beam test of a small MRPC which has 6 gaps of 220 $\mu$m and
an sensitive area of 20 $\times$ 20 cm$^2$. It has been operated with the
ecological HFO-1234ze gas ($\rm C_3F_4H_2$), and with the $\rm C_2F_4H_2/SF_6$
mixture. We have found that the ecological gas can substitute for the $\rm
C_2F_4H_2$-based gas mixture without significantly compromising the current
level of performance.
