Influence of two management practices in the Canadian Prairies on radiative forcing

Area of Science:

• Agricultural Science
• Climate Science
• Remote Sensing

Background:

• Agricultural management practices influence surface albedo and soil carbon sequestration, key factors affecting Earth's radiation budget and climate change.
• Understanding these impacts is crucial for developing effective climate change mitigation strategies in agricultural regions.

Purpose of the Study:

• To investigate the impact of reduced summer fallowing and reduced tillage in the Canadian Prairies on climate change.
• To estimate the change in radiative forcing attributed to alterations in surface albedo and soil carbon sequestration.

Main Methods:

• Utilized 10-day composite 250-m Moderate Resolution Imaging Spectroradiometer (MODIS) data to derive seasonal albedo variations based on agricultural practices and soil color.
• Integrated data from the Census of Agriculture to account for both albedo and soil carbon changes.
• Calculated radiative forcing and equivalent atmospheric CO2 drawdown associated with specific agricultural management changes.

Main Results:

• Conversion from summer fallowing to continuous cropping and from conventional tillage (CT) to no-tillage (NT) or reduced tillage (RT) resulted in an overall increase in surface albedo.
• The increase in albedo was influenced by soil brightness, vegetation type, and snow cover.
• Estimated total radiative forcing from 1981–2016 was -405 μW m⁻² for CT to NT/RT conversion and -410 μW m⁻² for reduced summer fallow, with albedo changes contributing significantly (70% and 62%, respectively).
• Equivalent atmospheric CO2 drawdown from albedo changes was approximately 7.8 and 8.7 Tg CO2 yr⁻¹ for the respective management changes.

Conclusions:

• Reduced summer fallowing and reduced tillage practices in the Canadian Prairies lead to a net radiative cooling effect.
• Both surface albedo and soil carbon sequestration must be considered when evaluating the climate change impacts of agricultural management.
• These findings highlight the potential of sustainable agricultural practices for climate change mitigation.