What Is the Average Temperature of Earth?

What is the temperature of Earth?

Despite the enormous variation in climates and regional temperatures around the world, scientists use an average temperature for the entire surface of the Earth to measure for atmospheric changes as a whole. Although local temperatures may grow either warmer or cooler from year to year, the overall average temperature of the Earth has been rising over the past century.

Significance

When scientists measure the average temperature of the Earth, they take many readings from the coldest and hottest places before calculating a mean temperature, generally agreed to be 15 degrees C, or 59 degrees F. The importance of global temperature is not this average, though, but rather in the changes to that average. Fluctuations occur naturally; however, a sustained rise in temperature over the course of time means the way of life for all living things changes as well.

Time Frame

In the past, temperatures changed for a various reasons, such as shifts in the Earth's orbit and tilt, differences in the sun's intensity or emissions from volcanic eruptions. Despite stable temperatures over the last 2,000 years, three historical periods deviated from this stability. From 900 to 1300 A.D., temperatures grew warmer than usual during an era called the Medieval Climate Anomaly; the Little Ice Age produced distinctly cooler than normal temperatures from 1500 to 1850 A.D.; the current Industrial Era has seen temperatures rise over the last 100 years.

Geography

Extreme northern and southern regions usually consist of permafrost, or perpetually frozen subsoil, and permanent ice caps cover the areas near the poles. Climate change has thawed these historical cold regions, causing ecological stress on the animals and plants adapted to live in these conditions. In addition, water freed from large-scale melting of previously permanent ice formations has raised sea levels and threatened some low-lying coastal areas with erosion and destruction of natural habitats.

Considerations

Many people use the term "global warming" to refer to a rise in the average temperature of the Earth. In some cases, however, this is a misnomer because some areas are experiencing colder temperatures, not warmer. Although the overall temperature is increasing in many geographical regions, other places are experiencing more severe winters and increased incidences of snowfall. Another term, "global climate change," provides a more appropriate way to discuss the changes occurring.

Theories/Speculation

The controversy surrounding global climate change revolves around its causes. Scientists working in the field of atmospheric science believe that humans have caused the rise in temperatures due in large part to the use of fossil fuels. Burning oil, gasoline, coal and other fuels produces gases, such as carbon dioxide (CO2), that form an insulating layer in the Earth's atmosphere. This invisible layer of gases functions like a greenhouse in preventing heat from escaping into space and thus raises the temperature of the Earth's surface.

Resources

• Read this Article in Spanish
• National Oceanic and Atmospheric Administration