Basics of Climate Science

	Weather and Climate
	Climatic Variables
	Components of Climate System
	Interaction among the Components of Climate System
	Layers of the Atmosphere

Climate Variation

Types of Climate Variation

Natural Climate Variation

	Natural Forcings of the Climate System
	Natural Variability of the Climate

Human-induced Climate Variation

Topic Summary

Natural Forcings of the Climate System

Natural forcings are of two types.
External Forcings: These are essentially linked to changes in the orbital parameters of the earth that control the intensity and location of incident solar radiation, and fluctuations in solar energy.
Internal Forcings: These comprise all those changes that occur within the earth system itself, in particular volcanic activity, fluctuations in ocean circulations and large-scale changes in the marine and terrestrial biosphere or in the cryosphere.

How does climate respond to natural forcings?

The response time of the various components of the climate system is very different. The system may respond to variations in external forcing across a wide range of space and over a varied timescale. When variation in the external forcings occurs, the response time of the various components of the climate system is very different.

Within the atmosphere, the response time of the troposphere is relatively short, from days to weeks, whereas the stratosphere comes into equilibrium within a time period of typically a few months.
Due to their large heat capacity, oceans have a much longer response time.
The biosphere may respond fast, for example to droughts, but may respond slowly to imposed changes.

But even without changes in external forcings, the climate may vary naturally, because, in a system of components with very different response times and non-linear interactions, the components are constantly varying and are never in equilibrium.

Article from "The Weather and Climate Impact Assessment Science Program"