Measured ice crystal number concentrations are often orders of magnitude higher than the number concentrations of ice nucleating particles, indicating the existence of secondary ice production (SIP) in clouds. Here, we present the first study to examine the global impacts of SIP through droplet shattering during freezing of rain, ice-ice collision fragmentation, and rime splintering, using a global climate model. Our results show that SIP happens pretty uniformly in the two hemispheres and dominates the ice formation in the moderately cold clouds with temperatures warmer than -15℃. SIP decreases the global averaged liquid water path by –14.6 g m^–2 (–22%), increases the global averaged ice water path by 8.7 g m^–2 (23%), improving the model agreement with observations. SIP changes the shortwave, longwave, and net cloud forcing by 2.1, –1.0, and 1.1 W m^–2, respectively, highlighting the importance of SIP on cloud properties on the global scale.