Shop Windows to the Universe

Dig into Montana Before History: 11K Years of Hunter-Gatherers in the Rockies and Plains by D. H. MacDonald, Ph.D. See our online store book collection.
Heat from the Sun supplies our planet with much-needed warmth. But over the past 150 years more heat has been retained by Earth as the amount of heat-trapping greenhouse gases in the atmosphere has grown.
Click on image for full size
Courtesy of USGS Astrogeology Research Program

What Controls the Climate?

A factor that has an affect on climate is called a “forcing.” Some forcings, like volcanic eruptions and changes in the amount of solar energy, are natural. Others, like the addition of greenhouse gases to the atmosphere, are caused by humans.

The Sun Affects Climate
The heat on Earth comes from the Sun, so climate can change if there is a change in the amount of solar energy that gets to Earth. Changes to the cycle of solar activity, called the 11-year solar cycle, can produce small but noticeable impact on climate. Recent climate change is too large to be caused by solar activity. On timescales of tens of thousands to hundreds of thousands of years, changes in the way Earth orbits the Sun can cause changes to climate.

Volcanic Eruptions Affect Climate
When volcanoes erupt they spew more than hot red lava and ash. Tiny particles called aerosols wind up in the atmosphere too. These tiny particles, made of sulfur dioxide, get into the stratosphere and reflect solar radiation back out to space. This causes cooling. The effect is temporary, lasting usually only a year or two.

Greenhouse Gases Affect Climate
Only a small portion of the molecules that are in Earth’s atmosphere are greenhouse gases, yet they have a strong affect. These gases trap heat through a process called the greenhouse effect. While greenhouse gases are a natural part of the atmosphere, their quantities have increased over the past 150 years due to burning of fossil fuels and decrease in the amount of forests which naturally take up the greenhouse gas carbon dioxide during photosynthesis.

Snow and Ice Affect Climate
The cryosphere, the frozen part of the Earth including snow and ice, has an impact on Earth’s climate. Because snow and ice are light in color, they have a high albedo – the ability to reflect most solar radiation back out to space. When snow and ice melt as Earth’s climate warms, less energy is reflected; this causes even more warming.

There are also other aspects of our planet that have an impact on climate too. Scientists are actively studying the impact of clouds on climate and the effect of aerosols on climate. Melting Arctic sea ice could change ocean circulation, producing a regional impact on climate. This is also an area of active research.

Last modified June 11, 2008 by Lisa Gardiner.

Shop Windows to the Universe Science Store!

The Summer 2010 issue of The Earth Scientist, available in our online store, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.

Windows to the Universe Community



You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

What is Climate?

Climate in your place on the globe is called regional climate. It is the average weather pattern in a place over more than thirty years, including the variations in seasons. To describe the regional climate...more

Solar Cycle Variations and Effect on Earth's Climate

Is it possible that the "solar constant" isn't so constant after all? For more than 100 years, scientists have wondered if cycles on the Sun and changes of the solar irradiance or energy received at Earth...more

Aerosols: Tiny Particulates in the Air

Aerosols, also called particulates, are tiny bits of solid or liquid suspended in the air. Some aerosols are so small that they are made only of a few molecules – so small that they are invisible because...more

Earth's Greenhouse Gases

Less than 1% of the gases in Earth's atmosphere are called greenhouse gases. Even though they are not very abundant, these greenhouse gases have a major effect. Carbon dioxide (CO2), water vapor (H2O),...more

Earth's Greenhouse Effect

Energy from the Sun can enter the atmosphere, but not all of it can easily find its way out again. This is a natural process called the greenhouse effect. Without any greenhouse effect, Earth’s temperature...more

Carbon Dioxide - CO2

Carbon dioxide is a colorless and non-flammable gas at normal temperature and pressure. Although much less abundant than nitrogen and oxygen in Earth's atmosphere, carbon dioxide is an important constituent...more


Photosynthesis is the name of the process by which autotrophs (self-feeders) convert water, carbon dioxide, and solar energy into sugars and oxygen. It is a complex chemical process by which plants and...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA