Phytoplankton Chlorophyll trends in the Arctic (1998-2022) at the local, regional, and pan-Arctic scales
Abstract
We analyzed the temporal trends (1998-2022) of surface phytoplankton Chlorophyll (Chl) concentration in the Arctic at the local, regional, and pan-Arctic scales. We used four empirically-derived Chl satellite ocean color products: three calibrated at the global scale, and one algorithm calibrated to Arctic waters. Depending on the months considered, between 10-40\% of the area with valid pixels showed statistically significant Chl trends, with $\sim2/3$ of those pixels showing Chl increases, and the other third indicating a decrease. At the pan-Arctic level, three of the Chl products suggest median Chl has increased by 12-16\% since 1998. However, the product calibrated to the Arctic did not show a statistically significant trend. Our findings suggest that Chl trends in the Arctic are heterogeneous, and that magnitude and significance of trends can vary depending on the satellite product used.