Attribution of recent climate change
Attribution of recent climate change is the effort to scientifically ascertain mechanisms responsible for recent changes observed in the Earth's climate, commonly known as 'global warming'. The effort has focused on changes observed during the period of instrumental temperature record, when records are most reliable; particularly in the last 50 years, when human activity has grown fastest and observations of the troposphere have become available. The dominant mechanisms (to which recent climate change has been attributed) are anthropogenic, i.e., the result of human activity. They are: increasing atmospheric concentrations of greenhouse gases global changes to land surface, such as deforestation increasing atmospheric concentrations of aerosols.There are also natural mechanisms for variation including climate oscillations, changes in solar activity, and volcanic activity.According to the Intergovernmental Panel on Climate Change (IPCC), it is ""extremely likely"" that human influence was the dominant cause of global warming between 1951 and 2010. The IPCC defines ""extremely likely"" as indicating a probability of 95 to 100%, based on an expert assessment of all the available evidence.Multiple lines of evidence support attribution of recent climate change to human activities: A basic physical understanding of the climate system: greenhouse gas concentrations have increased and their warming properties are well-established. Historical estimates of past climate changes suggest that the recent changes in global surface temperature are unusual. Computer-based climate models are unable to replicate the observed warming unless human greenhouse gas emissions are included. Natural forces alone (such as solar and volcanic activity) cannot explain the observed warming.The IPCC's attribution of recent global warming to human activities is a view shared by most scientists, and is also supported by 196 other scientific organizations worldwide (see also: scientific opinion on climate change).