Spatiotemporal change of NDVI in the Arctic Caused by Global Warming and Its Impact on Carbon Stock——A Case Study of Alaska

Abstract

Northern forests in Alaska store a large percentage of carbon. Besides, vegetation is quite sensitive to climate change. With the intensification of global warming, satellite images have observed a significant greening trend in the region (i.e., the growth of NDVI). In this paper, NDVI was applied to explore the spatiotemporal evolution of vegetation in Alaska and its links with climate variables. The trend of NDVI was estimated with linear regression and Theil Sen Median method. Besides, Pearson correlation coefficient between climate variables and NDVI was computed to explore the characteristics of vegetation in response to global warming. The carbon stock was estimated through Biomass Carbon Density Estimation Model. The results indicated that there was an uptrend in NDVI during 2000~2020. Precipitation was the dominant climate factor, more positively correlated with NDVI. On top of that, carbon estimation based on NDVI suggested that Alaska's average forest carbon stock is roughly 30.978t C/ha. According to the results, NDVI change is more susceptible to precipitation than temperature. The results can serve as a reference for monitoring local carbon dynamics.