Like other resources, heat can be recycled. This natural reuse and retention of atmospheric heat is called the greenhouse effect. Certain heat-retaining gases—called greenhouse gases—such as water vapor, carbon dioxide, methane and ozone are the primary molecules that retain this heat in the air.

Here’s how the basic process works. Solar energy that strikes our planet’s surface warms the ground. As the ground cools, heat is released to the atmosphere through conduction and convection. This is called sensible heat. Greenhouse gases readily absorb this energy, preventing its immediate release back into space. Also, when liquid water on Earth absorbs energy and changes state to water vapor, energy called latent heat energy is carried into the atmosphere. As you would expect, all of this retained heat warms the atmosphere.

 

In a balanced state, the amount of solar energy striking our planet will equal the amount released back into space. Thus with a stable greenhouse effect, our global temperature should remain elevated, but steady. In fact, some scientists report that the greenhouse effect has produced an environment about 35°C (63°F) warmer than it would be if there were no heat recycling.

 

These days, however, there seems to be less heat leaving the global system. This has produced a slow-but-steady rise in the average temperature of the oceans and atmosphere. This trend is called global warming. Global warming events have occurred many times in the geological history of our planet.

 

Many scientists have concluded that human activities, including the burning of fossil fuels, have contributed to this current increase in the levels of greenhouse gases. This has produced an atmosphere that retains increasing amounts of heat energy. The extra load of thermal energy not only warms the atmosphere, but increases Earth’s surface temperatures. More heat retention also results in a gradual rise in sea temperature.

 

The increased heat content of warmer seas and atmosphere may alter critical balances. Increased temperatures can melt ice, resulting in a rise in sea level. The higher temperatures may negatively impact Earth’s ecosystems. In addition, as sea temperatures rise, more energy is available to fuel monster storm systems.

 

Scientists are closely monitoring retreating glaciers, increasing sea-surface temperatures, and the frequency of monster storms. These things may indicate that the climate of Earth is changing.