Global Warming Causes and Effect

Causes

Components of the current radiative forcing as estimated by the IPCC Fourth Assessment Report.

Main articles: Attribution of recent climate change and Scientific opinion on climate change

The Earth's climate changes in response to external forcing, including variations in its orbit around the Sun (orbital forcing),^[13][14][15] volcanic eruptions,^[16] and atmospheric greenhouse gas concentrations. The detailed causes of the recent warming remain an active field of research, but the scientific consensus^[17][18] is that the increase in atmospheric greenhouse gases due to human activity caused most of the global warming observed since the start of the industrial era. This attribution is clearest for the most recent 50 years, for which the most detailed data are available. Some other hypotheses departing from the consensus view have been suggested to explain the temperature increase. One such hypothesis proposes that global warming may be the result of variations in solar activity.^[19][20][21]

None of the cause and effects of forcing are instantaneous. The thermal inertia of the Earth's oceans and slow responses of other indirect effects mean that the Earth's current climate is not in equilibrium with the forcing imposed. Climate commitment studies indicate that even if greenhouse gases were stabilized at 2000 levels, a further warming of about 0.5 °C (0.9 °F) would still occur.