Variability may be due to natural internal processes within the climate system (internal variability), or to variations in natural or human - induced external forcing (external variability). (climatehotmap.org)
Climate change may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions, and persistent anthropogenic changes in the composition of the atmosphere or in land use. (metlink.org)
Climate change may be due to natural internal processes or external forcings, or to persistent human - induced changes in the composition of the atmosphere or in land use. (climatehotmap.org)