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Integrating federal research on climate and global change

Ecosystems PDF Print E-mail
KEY MESSAGES:
  • Ecosystem processes, such as those that control growth and decomposition, have been affected by climate change.
  • Large-scale shifts have occurred in the ranges of species and the timing of the seasons and animal migration, and are very likely to continue.
  • Fires, insect pests, disease pathogens, and invasive weed species have increased, and these trends are likely to continue.
  • Deserts and drylands are likely to become hotter and drier, feeding a self-reinforcing cycle of invasive plants, fire, and erosion.
  • Coastal and near-shore ecosystems are already under multiple stresses. Climate change and ocean acidification will exacerbate these stresses.
  • Arctic sea ice ecosystems are already being adversely affected by the loss of summer sea ice and further changes are expected.
  • The habitats of some mountain species and coldwater fish, such as salmon and trout, are very likely to contract in response to warming.
  • Some of the benefits ecosystems provide to society will be threatened by climate change, while others will be enhanced.

Butterfly Range Shifts Northward

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The natural functioning of the environment pro- vides both goods – such as food and other products that are bought and sold – and services, which our society depends upon. For example, ecosystems store large amounts of carbon in plants and soils; they regulate water flow and water quality; and they stabilize local climates. These services are not assigned a financial value, but society nonetheless depends on them. Ecosystem processes are the underpinning of these services: photosynthesis, the process by which plants capture carbon dioxide from the atmosphere and create new growth; the plant and soil processes that recycle nutrients from decomposing matter and maintain soil fertility; and the processes by which plants draw water from soils and return water to the atmosphere. These ecosystem processes are affected by climate and by the concentration of carbon dioxide in the atmosphere.

The diversity of living things (biodiversity) in ecosystems is itself an important resource that maintains the ability of these systems to provide the services upon which society depends. Many factors affect biodiversity including: climatic conditions; the influences of competitors, predators, parasites, and diseases; disturbances such as fire; and other physical factors. Human-induced climate change, in conjunction with other stresses, is exerting major influences on natural environments and biodiversity, and these influences are generally expected to grow with increased warming.