Mapping pan-Arctic riverine particulate organic carbon from space (1985 to 2022)

Area of Science:

• Earth and Environmental Sciences
• Climate Science
• Arctic System Science

Background:

• High-latitude regions are experiencing intensified carbon release, significantly impacting the Arctic carbon cycle.
• Understanding changes in fluvial particulate organic carbon (POC) is crucial for assessing Arctic carbon budgets.

Purpose of the Study:

• To comprehensively analyze changes in fluvial POC concentrations (C_POC) and fluxes (F_POC) in pan-Arctic rivers from 1985 to 2022.
• To identify potential drivers of observed changes in Arctic riverine POC export.

Main Methods:

• Utilized satellite observations to analyze C_POC and F_POC across 578,000 km of river length.
• Compared data from 1985-2005 and 2006-2022 to quantify changes in POC fluxes.
• Correlated C_POC changes with climate variables (precipitation, temperature) and permafrost active layer depth.

Main Results:

• A net increase in C_POC was observed, with 18% of river length showing significant increases versus 11% showing declines.
• Total F_POC to the Arctic Ocean increased by 12.6% (0.49 Tg/year) between the two study periods (1985-2005 and 2006-2022).
• Significant correlations found between C_POC increases and increased precipitation (North America) and atmospheric warming (Eurasia), as well as deepening permafrost active layers.

Conclusions:

• Climate-driven fluvial POC export is a major component of the Arctic carbon budget.
• The study provides a high-resolution, satellite-based dataset essential for refining carbon cycle models.
• Findings underscore the sensitivity of the Arctic carbon cycle to ongoing climate change.