Direct Impacts of Climate Change on Freshwater Ecosystems

Changing climate is already having an impact on the physical, chemical and biological characteristics of freshwater ecosystems, both directly through changes in air temperature and precipitation and indirectly through interaction with other stressors. In future, non-climatic impacts should be reduced if pollutant loadings decrease and surface-water ecosystems are progressively restored. But global warming is very likely to continue, even if greenhouse gases and aerosols are kept constant at year 2000 levels, giving rise to a minimum projected average further increase in air temperature by 0.6°C by the end of this century (IPCC 2007). Changes in the characteristics of freshwater ecosystems as illustrated here are likely to continue and will become much more pronounced as greenhouse gas emissions rise and ecosystems cross critical thresholds that cause abrupt nonlinear system shifts to occur.