Environmental and societal factors such as air quality, water quality and availability, land use changes and expanding urbanization are already affecting human health and welfare, agriculture, and natural ecosystems in the Midwestern United States. Over this century, these existing stresses will likely be exacerbated by climate changes resulting from human activities. It is essential that policy decisions aimed at preserving the well-being of a region be informed by a good understanding of the region’s climate, how climate might change, and the uncertainties inherent in future projections. Recent updates in climate modeling expertise and an expanded view of possible non-intervention emission scenarios have narrowed the range of change that can be expected over the Midwest throughout the next century in some ways, while broadening it in others. In contrast to previous studies, which generally consider a mid-range scenario for future emissions, this study presents the range of change that would result from low to high scenarios for climate change. In this way we account for uncertainties in anthropogenic forcing on climate change in the region and quantify the potential effects of human actions on future climate. This analysis also combines the latest climate model projections with historical records of observed climate over the past century, effectively placing potential changes in extreme event frequencies such as heavy rainfall events and temperature threshold exceedances within the context of observed variability over the past century. The purpose of this study is to provide an updated picture of the potential impacts of climate change on the Midwest to inform the impact assessment and policy development community. From the magnitude of the changes projected by this study, it is clear that these must be included in future policy decisions in order to ensure the successful adaptation and survival of existing human and natural systems in the Midwest.
From the Introduction:
Climate provides fundamental limits on and opportunities for human activities and ecosystem functioning within the Great Lakes region. A changing climate could lead to alterations in the frequency and severity of droughts and floods; water supply; air, soil, and water quality; ecosystem health; human health; and resource use and the economy. Climate change may act through multiple pathways; interactions in and impacts on the Great Lakes ecosystem can be dynamic and non-linear. Within the Great Lakes watershed, there are already numerous stressors that cause ecosystem change including land use change, pollution, eutrophication, invasion of exotic species, and acid precipitation. A changing climate should be considered as another agent of change acting in concert with other ecosystem stresses.
Recognizing that this emerging issue required a survey of the potential impacts and the ability to adapt, the Great Lakes Water Quality Board commissioned a white paper to explore the implications of a changing climate on the Great Lakes watershed (Figure 1-1). The white paperaddresses four broad questions:
- What are the Great Lakes water quality issues associated with climate change?
- What are the potential impacts of climate change on the “beneficial uses” in the Great Lakes Water Quality Agreement?
- How might these impacts vary across the Great Lakes?
- What are the implications for decision-making?