Global carbon dioxide emissions from inland waters

Area of Science:

• Environmental Science
• Geochemistry
• Climate Science

Background:

• Carbon dioxide (CO2) evasion from inland waters is a critical but poorly quantified component of the global carbon cycle.
• Previous global estimates were limited by a lack of standardized frameworks for surface area, gas transfer velocity, and comprehensive CO2 databases.

Purpose of the Study:

• To establish a global framework for estimating CO2 evasion from inland waters.
• To analyze regional variations in inland water surface area, dissolved CO2, and gas transfer velocity.
• To provide updated global CO2 evasion rates.

Main Methods:

• Development of a framework to estimate inland water surface area and gas transfer velocity.
• Compilation of a global CO2 database for inland waters.
• Regional analysis of CO2 evasion rates from streams, rivers, lakes, and reservoirs.

Main Results:

• Global CO2 evasion rates estimated at 1.8 Pg C/yr from streams/rivers and 0.32 Pg C/yr from lakes/reservoirs.
• Total global CO2 evasion rate of 2.1 Pg C/yr, higher than prior estimates, driven by increased riverine flux.
• Identification of global hotspots in stream and river CO2 evasion, with 70% of flux from 20% of land surface.

Conclusions:

• Global CO2 evasion from inland waters is a substantial and underestimated carbon flux.
• Significant regional disparities exist in CO2 evasion, with concentrated 'hotspots' in riverine systems.
• Further research is necessary to elucidate the sources and mechanisms driving inland water CO2 evasion globally.