Course for graduate students 1.1 Definition Climate Change Climate change refers to any change in climate over time. whether due to natural variability or as a result of human activity. This usage differs from that in the United nations Framework Convention on Climate Change(UNFCCC), which defines climate change as: a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods. See also climate variability. 2021/2/22 Assessment of climate/change impacts 15of42Course for graduate students 2021/2/22 Assessment of climate/change impacts 15 of 42 1.1 Definition Climate Change Climate change refers to any change in climate over time, whether due to natural variability or as a result of human activity. This usage differs from that in the United Nations Framework Convention on Climate Change (UNFCCC), which defines "climate change" as: "a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods." See also climate variability