Projected Global Impacts on Ecosystems

Wildlife populations are directly and indirectly affected by climate. Climate

  • determines the vegetation in a region and therefore the base of the food chain.
  • affects behaviour of wildlife, such as breeding times.

Species, both plant and animal, are adapted to a temperature range in which they can survive. Change the climate and species have to relocate to a new habitat (if available) or adapt (given enough time). Entire ecosystems cannot move as one unit to a new location. Instead, at a given location, the species makeup and relative numbers will change.

Climate change will push the boundaries of freshwater fish distributions toward the poles. Cold- and cool-water fishes will lose habitat while warm-water fishes will gain. Impacts on coastal ecosystems, such as coral reefs, salt marshes, and mangrove forests will depend on the rate of sea level rise, changes in sea surface temperature, and human activity.

Many species and populations are already at high risk. They face greater risk from the combination of two kinds of change:
1. Climate change making some of their current habitat unsuitable
2. Land-use change breaking their habitat into isolated areas and creating obstacles to species migration.

Ecosystem disturbances such as fire, drought, pest infestation, invasion of species, storms, and coral bleaching events are expected to increase (see Table 1). There are other stresses on ecosystems such as land degradation, pollution, and harvesting. Add climate change to these stresses and the result is extensive damage to, or complete loss of some unique ecosystems, along with extinction of some endangered species. In some cases the threatened ecosystems are those that could diminish some climate change impacts, such as coastal systems that buffer the impacts of storms. (Coastal Zones and Marine Ecosystems), (Future Changes in Sea Level)

Table 1. Ecosystem effects of climate change if no climate policy interventions are made. Judgments of confidence use the following scale:

  • very high (95% or greater),
  • high (67-95%),
  • medium (33-67%),
  • low (5-33%),
  • very low (5% or less).



Source: IPCC Climate Change 2001 Synthesis Report p. 70


1. Measures can be taken to reduce the loss of biodiversity such as the establishment of refuges, parks and reserves with corridors to allow migration of species. Discuss other possibilities with your partner or your group. Identify two more methods to help preserve biodiversity.

2. Coral reefs and atolls, mangroves, boreal and tropical forests, polar and alpine ecosystems, prairie wetlands, and remnant native grasslands are all ecosystems threatened by climate change.
a. Choose one to research. (see Early Warning Signs)
b. Locate one example of your ecosystem on a world map.
c. Create a poster to display in a hallway of your school or in a shopping mall.. Clearly describe the ecosystem today and in 2100 if there is no climate policy intervention (refer to the table); Include species diversity, habitat, threats to the ecosystem. Use both text and visuals, with a world map showing the ecosystem name and location.

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