Slide 2: Climate variation
Weather and climate affect all manner of human and natural interactions. Weather is the day-to-day effects of natural conditions, but climate refers to an averaging of the mean of these effects over a time period (usually annual or multi-year, although climatic regions may be defined by seasonality of effects (eg: winter rainfall region)). Both systems are naturally variable. Climate is known to vary year on year (or even decadal variation). It is influenced on varying time scales by factors such as changes in the sun's output, the Earth's orbit, changes in the gaseous composition of the Earth's atmosphere and changes in the makeup of the Earth's surface, for instance vegetation cover (IPCC, 2001a). These short term changes are termed climate variability, or climate variation.
IPCC (2001): Climate Change 2001: The Scientific Basis. (Houghton, J.T., Ding, Y., Griggs, D.J., Noguer, M., van der Linden, P., Dai, X., Maskell, K. and Johnson, C.A., Eds.). Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press.