Core Insights - Climate change is weakening the carbon sink capacity of Arctic fjords, which is crucial for regulating atmospheric CO2 and global climate [1][2] - The study focuses on the dynamic fjord system of Kongsfjorden in the Svalbard archipelago, revealing significant changes in phytoplankton community structure due to sea ice melt and changes in water properties [1][2] Group 1: Impact of Climate Change - The Arctic fjord has historically been an important carbon storage system, but rising temperatures are threatening its stability and efficiency [1] - Initial increases in sunlight due to reduced sea ice stimulate phytoplankton growth, but this leads to water stratification, limiting nutrient supply from deeper waters [2] Group 2: Ecological Consequences - The increase in phytoplankton biomass is countered by nutrient scarcity, challenging the assumption that higher primary productivity directly translates to increased carbon storage capacity [2] - Accelerated glacier retreat alters the timing and quantity of glacial meltwater entering the sea, causing fluctuations in nutrient supply and destabilizing the entire ecological nutrient system [2] Group 3: Research Significance - The findings serve as an early warning signal for the limits of natural carbon storage under rapid environmental changes in the Arctic [2]