Climate change has a significant effect on the spatial distribution,structure and function of ecosystems. To understand the effects and feedback mechanisms of climate change on a large spatial and temporal scale,the distribution,shift ranges and net primary production(NPP)of grassland ecosystems across the globe from 1911 to 2010 have been simulated using the Comprehensive Sequential Classification System(CSCS)and a segmentation model.Correlation analysis was also conducted to reveal the responses of grassland types to different climate variables.The results showed that the total global area of grassland ecosystems declined from 5175.73*10~4 km~2 in the 1920s to 5102.16*10~4 km~2 in the 1990s.The largest decrease,192.35*10~4 km~2,occurred in tundra &alpine steppe ecosystems.The areas of desert grassland,typical grassland and temperate humid grassland decreased by 14.31,34.15 and 70.81*10~4 km~2 respectively,while tropical savanna expanded by 238.06*10~4 km~2.Climate warming forced most grasslands to shift northwards,particularly in the northern hemisphere.Global grassland NPP increased from 25.93 Pg DW/yr in the 1920s to 26.67 Pg DW/yr in the 1990s.In terms of each grassland type,the NPP of the tundra and alpine steppe,desert grassland,typical grassland and temperate humid grassland decreased by 709.57,24.98,115.74 and 291.56 Tg DW/yr respectively. The NPP of tropical savanna increased by 1887.37Tg DW/yr.At the global scale,precipitation was the dominant factor affecting grassland NPP.In general,grassland ecosystems have been substantially affected by climate change over the past 100 years.Although the global grassland NPP showed an overall increasing trend, the structure and distribution of particular grassland ecosystems had been adversely affected by the warmer and wetter climate.