The Greenhouse effect

What is the greenhouse effect?

The greenhouse effect is a natural process that helps keep a layer of warm air around the Earth to maintain temperatures that support life.

Carbon dioxide, methane , nitrous oxide and other greenhouse gases collecting in the upper atmosphere contribute to this process. The gases act like a blanket to trap and hold in heat from the sun.

This figure is a simplified, schematic representation of the flows of energy between space, the atmosphere, and the Earth's surface, and shows how these flows combine to trap heat near the surface and create the greenhouse effect. Energy exchanges are expressed in watts per square metre (W/m2). Learn more at Wikipedia

Human activities over the past few hundred years have contributed to an increase in the amount of greenhouse gases in the atmosphere. This has made the blanket of gases thicker, trapping more heat.

A diagram of the natural greenhouse effect on earth, where the Earth's temperature is kept constant to support life.	A diagram showing how additional greenhouse gases trap more heat in the Earth’s atmosphere and raises the temperature.
Source: Reproduced with permission from the Australian Greenhouse Office , Department of the Environment and Heritage

Not only does the increase in heat cause warmer temperatures, called global warming, many scientists also believe it makes the weather more unpredictable.

Melting ice at the north and south poles raise the sea level, causing major floods in low-lying areas or even sinking small islands. Sea currents that circulate heat around the planet can slow down, change direction or stop. Cyclones and tsunamis may increase in frequency or intensity. Less snow falls on ski fields, and less water is available to melt and run into rivers.