###### Abstract  
Global warming has greatly stimulated vegetation growth through both extending the growing season and promoting photosynthesis in the Northern Hemisphere (NH). Analyzing the combined dynamics of such trends can potentially improve our current understanding on changes in vegetation functioning and the complex relationship between anthropogenic and climatic drivers. This study aims to analyze the relationships (long-term trends and correlations) of length of vegetation growing season (LOS) and vegetation productivity assessed by the growing season NDVI integral (GSI) in the NH (>30\({}^{\circ}\)N) to study any dependency of major biomes that are characterized by different imprint from anthropogenic influence. Spatial patterns of converging/diverging trends in LOS and GSI and temporal changes in the coupling between LOS and GSI are analyzed for major biomes at hemispheric and continental scales from the third generation Global Inventory Monitoring and Modeling Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) dataset for a 32-year period (1982-2013). A quarter area of the NH is covered by converging trends (consistent significant trends in LOS and GSI), whereas diverging trends (opposing significant trends in LOS and GSI) cover about 6% of the region. Diverging trends are observed mainly in high latitudes and arid/semi-arid areas of non-forest biomes (shrublands, savannas, and grasslands), whereas forest biomes and croplands are primarily characterized by converging trends. The study shows spatially-distinct and biome-specific patterns between the continental land masses of Eurasia (EA) and North America (NA). Finally, areas of high positive correlation between LOS and GSI showed to increase during the period of analysis, with areas of significant positive trends in correlation being more widespread in NA as compared to EA. The temporal changes in the coupled vegetation phenology and productivity suggest complex relationships and interactions that are induced by both ongoing climate change and increasingly intensive human disturbances. p 10.339.07.0000-0000-0000-0000-0000-0000-0000-0000-00000-00000-0000-00000-00000-000000-000000-000000-0000000-00000000000000000000000000000000000000000000000000  
in vegetation photosynthesis could have large effects on the role of terrestrial ecosystems as a carbon sink [11; 12; 13; 14]. Thus, in the context of ongoing global warming, monitoring long-term vegetation activity changes at regional and global scales can help to quantify and understand the effects of climate change on various terrestrial ecosystems and their feedbacks [3; 15]. Long-term time-series satellite data have been widely used to study vegetation activity at various spatial and temporal scales [6; 16; 17; 18; 19], such as the NDVI (Normalized Difference Vegetation Index) dataset that is produced by the Global Inventory Monitoring and Modeling Studies (GIMMS) group from the Advanced Very High Resolution Radiometer (AVHRR) of National Oceanic and Atmospheric Administration (NOAA). The GIMMS3g NDVI (starting in July 1981) has been widely used as a proxy for vegetation productivity by the global change research community. GIMMS NDVI-based studies have shown that the length of vegetation growing season (LOS) has increased in most areas of the Northern Hemisphere (NH) from 1982 to the late 1990s through an advancing start of growing season (SOS) and/or delaying end of growing season (EOS) due to climate change [6; 16; 17; 18; 20; 21]. However, since the end of the 1990s, this advancing trend of SOS has been shown to be weakened, and even reversed, in some regions [6; 7; 14; 22; 23; 24; 25; 26], although there is no consensus about when the reversal happened.