Elevation-Dependent Changes to Plant Phenology in Canada's Arctic Detected Using Long-Term Satellite Observations

Arctic temperatures have increased at almost twice the global average rate since the industrial revolution. Some studies also reported a further amplified rate of climate warming at high elevations; namely, the elevation dependency of climate change. This elevation-dependent climate change could have important implications for the fate of glaciers and ecosystems at high elevations under climate change. However, the lack of long-term climate data at high elevations, especially in the Arctic, has hindered the investigation of this question. Because of the linkage between climate warming and plant phenology changes and remote sensing's ability to detect the latter, remote sensing provides an alternative way for investigating the elevation dependency of climate change over Arctic mountains. This study investigated the elevation-dependent changes to plant phenology using AVHRR (Advanced Very High Resolution Radiometer) time series from 1985 to 2013 over five study areas in Canada's Arctic. We found that the start of the growing season (SOS) became earlier faster with an increasing elevation over mountainous study areas (i.e., Sirmilik, the Torngat Mountains, and Ivvavik National Parks). Similarly, the changes rates in the end of growing season (EOS) and the growing season length (GSL) were also higher at high elevations. One exception was SOS in the Ivvavik National Park: no warming trend with the May-June temperature at a nearby climate station decreased slightly during 1985-2013, and so no elevation-dependent amplification.

Automated summary

Arctic temperatures have increased at almost twice the global average rate since the industrial revolution, with higher rates of climate warming at high elevations. This study utilized AVHRR time series data to investigate elevation-dependent changes to plant phenology in five study areas in Canada's Arctic, finding faster changes in the start of the growing season with increasing elevation in mountainous areas.