Climate is classified based on temperature and precipitation patterns using the Koppen climate classification system. Climate change refers to significant shifts in the mean state or variability of the atmosphere over time. Evidence from paleoclimatology using proxies like tree rings and ice cores indicates the climate has changed in the past in response to factors like orbital variations, solar activity, atmospheric composition, and continental drift. Current climate change is increasing global temperatures, particularly in the Arctic, raising concerns about impacts like sea level rise.