It is widely acknowledged that the amount of carbon dioxide and other so-called greenhouse gases in the atmosphere are increasing. If current trends continue, the amount of carbon dioxide in the atmosphere will double during the 21st century, with further increases thereafter. The amounts of other greenhouse gases will also increase during the 21st century due primarily to human activities. The accumulation of carbon dioxide and other greenhouse gases in the atmosphere will change the climate by enhancing the greenhouse effect, leading to an increase in the Earth's average surface temperature. Because most greenhouse gases remain in the atmosphere for a long period of time, even if emissions from human activities were to stop immediately, the effect of accumulated past emissions would persist for centuries.
Climate change is one of the major threats to biodiversity at both the species and ecosystem levels.
This is because the rate of global climate change is projected to be more rapid than any change in climate that has occurred in the last 10,000 years. Species will be more vulnerable because of climate change, and even where they are able to tolerate changes, they will have to deal with a variety of new competitors, predators, diseases, and alien species for which they have no natural defense. Desertification may accelerate in some regions. Climatic change could dramatically alter the distribution of wetlands and freshwater resources. Sea level rise, increasing ocean temperatures, and changes in storm patterns will threaten coral reefs, mangroves and other coastal and marine resources.