Climate change is a change in the statistical distribution of weather patterns when that change lasts for an extended period of time. It may refer to a change in average weather conditions, or in the time variation of weather around longer-term average conditions.
Climate change is caused by factors such as biotic processes, variations in solar radiation received by Earth, plate tectonics, and volcanic eruptions.
Therefore, the climate system can respond abruptly, but the full response to forcing mechanisms might not be fully developed for centuries or even longer. Forcing mechanisms can be either “internal” or “external”. Internal forcing mechanisms are natural processes within the climate system itself (e.g., the thermohaline circulation). External forcing mechanisms can be either natural.
Whether the initial forcing mechanism is internal or external, the response of the climate system might be fast (e.g., a sudden cooling due to airborne volcanic ash reflecting sunlight), slow (e.g. thermal expansion of warming ocean water), or a combination (e.g., sudden loss of albedo in the arctic ocean as sea ice melts, followed by more gradual thermal expansion of the water).
Consisting of glacial periods
All climate models balance, or very nearly balance, incoming energy as short wave (including visible) electromagnetic radiation to the earth with outgoing energy as long wave (infrared) electromagnetic radiation from the earth. Any imbalance results in a change in the average temperature of the earth.
Some of the variability does not appear to be caused systematically and occurs at random times. Such variability is called random variability or noise. Earth has undergone periodic climate shifts in the past.
Paleoclimatology is the study of past climate over a great period of the Earth’s history. It uses evidence from ice sheets, tree rings, sediments, coral, and rocks to determine the past state of the climate.
Therefore, the climate system can respond abruptly, but the full response to forcing mechanisms might not be fully developed for centuries or even longer. Forcing mechanisms can be either “internal” or “external”. Internal forcing mechanisms are natural processes within the climate system itself (e.g., the thermohaline circulation). External forcing mechanisms can be either natural.
Source: Wikipedia