We examined both long-term natural climate change and anthropogenic contributions to current climate change for the Xinjiang province of northwest China. Xinjiang encompasses a northern semiarid region and a more arid southern region, both of which showed a substantial warming trend over the past 50 years. We also compared human contributions to climate change between the northern and southern part of Xinjiang, including land use/land cover, population, and greenhouse gas production in the two regions. Urban areas acted as heat islands; large areas of grassland and forest were degraded or turned into barren land, especially in north Xinjiang. Additionally, north Xinjiang also showed larger increase in population and greenhouse gas emissions mainly associated with animal production than south Xinjiang. We found Xinjiang, although a geographically coupled mountain basin system, consists of two regions with distinct climate patterns and anthropogenic activities related to greenhouse gas production. This will require different management strategies to alleviate climate change impacts and reduce anthropogenic contributions to greenhouse gas production.