Introduction to the Global Climate System

No matter where we live on Earth the weather and climate play an important part in our daily lives.   The weather is the changing conditions in the atmosphere that occur all around in the present such as rain, snow, wind or sunshine.

Climate is regional or global and is defined by the long term averages of the extremes and variations in conditions and temperatures over extended periods of time. The climate system is how the atmosphere conditions are influenced by land and ice masses and oceans and how these affect the surface of the Earth. It is comprised of the following five elements that interact with one another and are influenced by other factors such as the Sun, volcanic eruptions and human activity.

Elements of the climate system

The atmosphere, the hyrdosphere, the biosphere, the cryosphere and the geosphere.   These elements react and interact in complicated and multifarious ways with differing strengths producing a great many variations in weather from region to region.  Matters are further complicated by the actions of humans on land, on water and in the atmosphere, volcanic eruptions and sunspots.

The atmosphere

Surrounding the Earth is a thin coat comprising of a mixture of gases and moisture called the atmosphere.  This covering insulates the Earth helping to prevent conditions becoming too hot, or too cold.  Weather and climate are influenced by the way it circulates, heat from terrestrial radiation and light from solar radiation and the various ways these interact with each other and other agents.

The hydrosphere

The oceans and seas are termed the hydrosphere.  The atmosphere and the ocean are in a continuous cycle of exchanging heat and water and the movement of the seas affects the climate.  Heat can be soaked up or dispersed by the ocean with warm and cold currents and evaporation cools the atmosphere.   Interactions between the ocean waters and the atmosphere bring the the El Niño and La Niña cycles.

The land mass

On land large areas of vegetation such as rain forests, hills and mountains have an effect on air movement, temperatures, the water cycle and the absorption of energy from the sun. 

The cryosphere

The polar regions of Antarctica and the Arctic as well as the Greenland have great swathes of snow and ice termed as the cryosphere.  Ocean ice sheets insulate by trapping heat in the water.  Between 80-90% of energy from the Sun is reflected from snow covered land but land that is snow free only reflects around 10-20% of the energy.

The biosphere:

The land, air, water and surface rocks are where life is found and is termed the biosphere.  This is a major influence in the concentration of carbon dioxide in the atmosphere and the carbon cycle.

The climate system

These five elements interact with each other in many complex ways that are still not fully understood, though new scientific techniques and pictures from satellites orbiting the planet are helping to improve our understanding of the climate system.  

Influences on the climate system

The most important and most powerful influence on the climate system is the Sun.  Energy radiated from the Sun is returned to space from the surface of the Earth and it is important that a balance is maintained.  Cyclical fluctuations ion the Earth’s orbit around the Sun are also known to cause Ice Ages in the past.  Sunspots can also influence conditions on earth.

Volcanic eruptions can spew great cloud of ash and smoke into the atmosphere affecting the amount of energy the Earth receives from the Sun affecting weather and climate over vast regions.

Human activity has been a growing influence since the Industrial Revolution beginning around the middle of the 18th century.  For example, the increased burning of fossil fuels for industry and in people’s homes has resulted in an increase in greenhouse gases that have changed the composite make-up of the atmosphere.    Also the release of chlorofluorocarbons (CFCs) has caused a hole to form in the ozone layer.  Land use such as growing urbanization and deforestation can also affect local and regional climate and possibly global as well.