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Climate Change Impacts:
Wetlands and Shorebirds
Illinois wetlands and the species that depend on them are likely to face growing challenges from increased run-off, more intense flooding, and lower summer water levels. These factors, combined with already existing human pressures, will impact the services wetland ecosystems provide—such as water purification and flood control. Among the potential impacts of climate change with implications for wetlands in Illinois are:

• A Reduction in Flood-Absorbing Capacity
  The combined pressures of development and climate change will degrade the flood-absorbing capacity of wetlands and floodplains. This could lead to increased erosion, additional water pollution, and delayed recovery from acid rain.
  
  
• A Release of Nutrients and Heavy Metals
  Fluctuations in water levels and soil moisture influence the release of nutrients and heavy metals. Lower water levels expose more organic wetland soils to oxygen and may reduce mercury exports, but also may reduce the removal of nitrate from the soil. Increased oxygen concentrations in exposed soils—especially when accompanied by acid precipitation—may release metals such as cadmium, copper, lead, and zinc. Thus, wetlands downstream of industrial effluents could face increased risk of heavy metal contamination during periods of low water.
  
  
• A Loss of Breeding Sites
  Wetland losses and changes in the timing and severity of flood patterns will likely reduce safe breeding sites for amphibians and waterfowl. These changes may also cause many migratory species, such as Canada geese, to winter further north.
  
  
• Changes in Wetland Habitat
  Projected declines in summer rainfall will cause drying of prairie potholes and similar depressional wetlands. Dropping water levels will cause wetlands to shrink and new vegetation may colonize formerly open-water habitats on some exposed shorelines, thus creating new types of habitat. These changes will likely impact the total amount of wetlands in Illinois, which has already seen an 85% decrease due to draining.