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Greenhouse Gases and Aerosols

NOAA's research laboratories and programs are leaders in monitoring and investigating the properties and influences of trace gases and small particles in the atmosphere. Through careful and consistent measurements around the globe, and through laboratory and field experiments, researchers have pioneered ways to learn more about these gases and how they can affect regional and global climate.

This work is crucial in meeting NOAA's mission to understand and predict changes in Earth's environment. An objective of this research is to help reduce uncertainty in climate projections by providing information on the forcing mechanisms and feedbacks that contribute to changes in the Earth's climate.

Greenhouse Gases

The Earth's atmosphere is made up mostly of nitrogen (78%) and oxygen (21%), with a small amount of "trace gases" (1%) mixed in. But, that tiny percentage of trace gases - such as carbon dioxide, ozone, methane, and carbon monoxide - contribute in a big way to changes in the Earth's climate.

Such trace gases, also called greenhouse gases, allow energy from the sun (known as shortwave radiation) to reach the earth's surface, but absorb energy emitted from the earth (known as longwave radiation); this affects the surface energy balance of the planet by warming the atmosphere directly above it resulting in long-term changes to global climate. Although a greenhouse also works by trapping energy from the sun, the physics is different. The roof of a greenhouse is a slab of glass that traps radiation emitted from the ground which prevents convection (i.e. rising hot air) from allowing heat to escape. The atmospheric greenhouse is based on certain molecules (e.g. carbon dioxide) absorbing radiation at particular wavelengths (such as that emitted from the ground) and reemitting a portion back to the ground. Although an excess of greenhouse gas results in global warming, naturally occurring greenhouse gases are beneficial in keeping our planet at a comfortable temperature.

NOAA conducts lab and field investigations to discover the properties of greenhouse gas molecules that contribute to heating of the Earth. Some of these, like carbon dioxide, have always been present in the atmosphere, but are increasing due to human activity.

Others might be new compounds, introduced into the air by new manufacturing processes. For example, a molecule that was designed to be used to replace ozone-eating chlorofluorocarbons (CFCs) was closely examined by a NOAA laboratory, revealing it could have significant implications for global warming.

NOAA has developed a worldwide air sampling network that measures trace gases in the atmosphere. By collecting air samples in remote areas, including four baseline observatories at Antarctica, Mauna Loa on Hawaii, American Samoa, and Barrow, Alaska, NOAA researchers are trying to understand where greenhouse gases come from and where they go.

Aerosols

Small particles in the atmosphere - from smoke, dust, manufacturing, and other sources - can affect how the Earth system behaves. For example, aerosols can absorb and scatter radiation, which can cause either warming or cooling of the atmosphere. They also are important to the formation and behavior of clouds, and can influence the water cycle and the Earth's radiative balance.

NOAA researchers have set up a global aerosol monitoring network to help them study the properties and answer questions about aerosols and their effect on climate.

In addition, by using both ship-based and land-based observations, NOAA is trying to understand the distribution of human-made and natural aerosols in the atmosphere above the oceans and how they mix with land-based aerosols, as well as looking at the processes that lead to their formation, evolution and properties.

NOAA Research programs that study Greenhouse Gases and Aerosols

Earth System Research Laboratory (ESRL)
Air Resources Laboratory (ARL)
Climate Program Office (CPO)
Pacific Marine Environmental Laboratory (PMEL)

NEXT -- Modeling Climate

Updated June 12, 2007