Climate variability is a transient change in the climate, above or below the long term average. This can occur on different timescales.
Natural variability is the main reason for year to year differences in our climate.
There are many different processes that interact to influence the climate we experience. Natural variability refers to changes in the climate that occur due to factors other than human influence. These include processes such as large scale climate modes like the El Niño Southern Oscillation (ENSO) or Volcanic eruptions which can have a cooling effect or small changes in the energy received from the sun.
Briefing: Climate modelling – an overview
Briefing: A closer look at climate modelling