Meeting Documents

SIF Opens New Frontiers for Quantifying the Phytoplankton Response to Climate-Driven Arctic Ocean Transformations

Abstract

The observed and projected decline in Arctic sea-ice extent has significant ecological consequences. Climate change is not only reducing sea-ice area and thickness but is also altering the community structure and phenology of high-latitude marine ecosystems. Phytoplankton are particularly vulnerable to the loss of critical sea-ice habitats, increased ocean acidification, and rising sea-surface temperatures. While satellite observations have provided an unprecedented overview of chlorophyll a concentration as a proxy for phytoplankton biomass, uncertainties remain regarding the accurate estimation of the total photosynthetic activity of phytoplankton.

Solar-induced chlorophyll fluorescence (SIF) has emerged as a valuable tool for gaining physiological insights into direct photosynthetic processes. However, the short data record of SIF makes it challenging to assess the impact of climate change, which is undergoing rapid physical transformations. Here, we present an overview of a modeling framework we developed to extend TROPOMI SIF data over the 2004–2020 period. This enables us to provide a more comprehensive assessment of long-term phytoplankton dynamics.

We assess SIF-based biological responses of phytoplankton over the Arctic Ocean by comparing them with traditional observational estimates of chlorophyll-a and Normalized Fluorescence Line Height (NFLH). Our novel dataset provides a new pathway for monitoring the physiological responses of phytoplankton to ongoing climate change. The application of this new dataset is expected to provide new insights into how phytoplankton respond across time and space to environmental shifts, contributing to a more nuanced understanding of their role in shaping high-latitude marine ecosystems.