CAREER: The role of ecosystem management on boundary layer development and precipitation in the Northern Plains

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Global temperatures are rising, largely due to the effects of greenhouse gases from human activities on the amount of radiation from the Sun that is absorbed at the surface of the Earth instead of being reflected back to space. Within this global context are some regional cooling trends that also result from human activity, including those that are beneficial to economic and conservation objectives. One of these cooling trends has been found in the summer in the northern North American Great Plains. Maximum air temperatures have decreased by over three degrees and rainfall has increased by an inch during summer across parts of the Canadian Prairie Provinces since the 1970s. These changes are thought to be due to a decrease in the practice of keeping farm fields fallow during summer; Canada alone has lost around 35 million acres of fallow from the 1970s to the present. The United States has seen a similar decline in fallow area, largely in the Northern Great Plains, but the effects of these changes on regional climate in the U.S. have not been studied to date. Fallow was, and still is, widely practiced to save water for subsequent crops in dry regions, but also increases soil erosion and degradation and is not considered sustainable. Producers have also realized that the water-savings benefit of fallow is often outweighed by the economic losses of not planting a crop. The goal of this project is to understand how agricultural management practices that improve soil conservation and may increase on-farm income can also be beneficial to climate, both now and over the coming decades. As part of the project, a field course will be designed to link Tribal Colleges in the Montana University System with the goal of enhancing STEM education among underrepresented students. Project activities will also enhance existing efforts to improve after-school educational programs at the grade-school level. An inter-university consortium will be designed to coordinate research activities in the atmospheric sciences across Montana, including Tribal Colleges. To understand the role of land management on regional climate, it is necessary to understand the mechanisms by which it influences the climate system, and to integrate this understanding into models that can predict future climate dynamics. In a region with substantial fallow, warm and dry air from near the land surface rises and creates a high and dry atmospheric boundary layer that is unlikely to experience convective precipitation. If plants are present, more moisture and less heat enters the atmosphere, resulting in a moister atmospheric boundary layer that is not nearly as high, which makes cloud formation convective precipitation processes more likely. In this project, the exchange of heat and water between the surface and atmosphere in fallow, grasslands, and crops will be measured, and atmospheric boundary layer development, convective precipitation, and regional climate modeled. Models will be run over the past three decades to understand how management trends have influenced climate and over the forthcoming three decades to understand how future land management changes may, or may not, continue to counter global warming trends.