Cooling Trends from Agricultural Management Practices that Conserve Soil Carbon Resources in the North American Northern Great Plains: Important First Steps in the Transition toward a BECCS Economy
Abstract
The transition toward the Bio-energy with Carbon Capture and Storage (BECCS) economy may have unintended climate drawbacks, but also benefits. Parts of the North American northern Great Plains have experienced a remarkable 6 W m-2 decrease in summertime radiative forcing since the 1970s. Extreme temperature events now occur less frequently, maximum temperatures have decreased by some 2 °C, and precipitation has increased by 10 mm per decade in some areas. This regional trend toward a cooler and wetter summer climate has coincided with changes in agricultural management. Namely, the practice of keeping fields fallow during summer (hereafter `summerfallow') has declined from 15 Mha in the 1970s to 2 Mha at the present in the Canadian Prairie Provinces, and from 16 Mha to 6 Mha in the US, with the largest declines in the Northern Plains. In addition to potential climate impacts, replacing summerfallow with no-till cropping systems results in lesser soil carbon losses - or even gains - and usually confers economic benefits. In other words, replacing summerfallow with no-till cropping may have resulted in a `win-win-win' scenario for climate, soil carbon, and farm-scale economics. The interaction between carbon, climate, and the economy in this region - and the precise domain that has experienced cooling - are still unknown, which limits our ability to forecast the dynamics of the coupled human-climate system during the transition toward a BECCS economy. Here, we use eddy covariance measurements to demonstrate that summerfallow results in carbon losses during the growing season of the same magnitude (ca. 100 g C m-2 per growing season) as carbon uptake by dryland crops. We use surface-atmosphere energy flux measurements to model atmospheric boundary layer and lifted condensation level heights to demonstrate that observed regional changes in near-surface humidity (of up to 7%) are necessary to simulate observed increases in convective precipitation. We analyze climate data to demonstrate that areas with extensive summerfallow decline are not necessarily those that have experienced summer cooling, and we provide a framework for quantifying connections between climate, carbon, and economic drivers in the Upper Missouri River Basin as the transition to the BECCS economy continues.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMGC23B1238S
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCESDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 1630 Impacts of global change;
- GLOBAL CHANGE