The predicted effects of global warming on the environment and for human life are numerous and varied. It is generally difficult to attribute specific natural phenomena to long-term causes, but some effects of recent climate change may already be occurring. Raising sea levels, glacier retreat, Arctic shrinkage, and altered patterns of agriculture are cited as direct consequences, but predictions for secondary and regional effects include extreme weather events, an expansion of tropical diseases, changes in the timing of seasonal patterns in ecosystems, and drastic economic impact. Concerns have led to political activism advocating proposals to mitigate, eliminate, or adapt to it.
The 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC) includes a summary of the expected effects
The 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC) includes a summary of the expected effects
Projected climate changes due to global warming have the potential to lead to future large-scale and possibly irreversible effects at continental and global scales. The likelihood, magnitude, and timing is uncertain and controversial, but some examples of projected climate changes include significant slowing of the ocean circulation that transports warm water to the North Atlantic, large reductions in the Greenland and West Antarctic Ice Sheets, accelerated global warming due to carbon cycle feedbacks in the terrestrial biosphere, and releases of terrestrial carbon from permafrost regions and methane from hydrates in coastal sediments.
The probability of one or more of these changes occurring is likely to increase with the rate, magnitude, and duration of climate change. Additionally, the United States National Academy of Sciences has warned, "greenhouse warming and other human alterations of the earth system may increase the possibility of large, abrupt, and unwelcome regional or global climatic events. . . Future abrupt changes cannot be predicted with confidence, and climate surprises are to be expected."
The IPCC finds that the effects of global warming will be mixed across regions. For smaller values of warming (1 to 3 °C), changes are expected to produce net benefits in some regions and for some activities, and net costs for others. Greater warming may produce net costs (or to reduce the benefits from smaller warming) in all regions. Developing countries are vulnerable to reduced economic growth as a result of warming.
Most of the consequences of global warming would result from one of three physical changes: sea level rise, higher local temperatures, and changes in rainfall patterns. Sea level is generally expected to rise 18 to 59 cm (7.1 to 23.2 inches) by the end of the century
The probability of one or more of these changes occurring is likely to increase with the rate, magnitude, and duration of climate change. Additionally, the United States National Academy of Sciences has warned, "greenhouse warming and other human alterations of the earth system may increase the possibility of large, abrupt, and unwelcome regional or global climatic events. . . Future abrupt changes cannot be predicted with confidence, and climate surprises are to be expected."
The IPCC finds that the effects of global warming will be mixed across regions. For smaller values of warming (1 to 3 °C), changes are expected to produce net benefits in some regions and for some activities, and net costs for others. Greater warming may produce net costs (or to reduce the benefits from smaller warming) in all regions. Developing countries are vulnerable to reduced economic growth as a result of warming.
Most of the consequences of global warming would result from one of three physical changes: sea level rise, higher local temperatures, and changes in rainfall patterns. Sea level is generally expected to rise 18 to 59 cm (7.1 to 23.2 inches) by the end of the century
