[Image:3 examples of internal climate variability (1950-2012), the El Niño – Southern Oscillation, the Arctic Oscillation, and the North Atlantic Oscillation (NOAA).png|thumb |right |alt=Refer to caption |This image shows three examples of internal climate variability measured between 1950 and 2012: the
El Niño–Southern oscillation, the
Arctic oscillation, and the
North Atlantic oscillation.]]
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: