Carbon Dioxide. Carbon dioxide naturally composes about. Plants and eubacteria use carbon dioxide during photosynthesis. Humans, other animals, and plants add it to the air through respiration. Carbon dioxide is a heat-trapping greenhouse gas. Carbon monoxide in the air comes from burning fuel in vehicles, volcanoes, and forest fires. It is a poisonous gas. Methane gas is released into the air from landfills, livestock and their manure, and from oil and gas wells. It is also created when organic material decomposes.
It is a heat-trapping greenhouse gas. Sulfur oxides are produced when coal and oil are burned. The sulfur oxides mix with water droplets in the atmosphere to create sulfuric acid, which is a component of acid rain.
Skip to main content. More About Air Quality. More About the Atmosphere. Nitrogen Oxides. JavaScript appears to be disabled on this computer. Please click here to see any active alerts. A million metric tons is equal to about 2.
For comparison, a small car is likely to weigh a little more than 1 metric ton. Thus, a million metric tons is roughly the same mass as 1 million small cars! The U. Inventory uses metric units for consistency and comparability with other countries. GHG emissions are often measured in carbon dioxide CO 2 equivalent. Concentration, or abundance , is the amount of a particular gas in the air. Larger emissions of greenhouse gases lead to higher concentrations in the atmosphere.
Greenhouse gas concentrations are measured in parts per million, parts per billion, and even parts per trillion. One part per million is equivalent to one drop of water diluted into about 13 gallons of liquid roughly the fuel tank of a compact car. To learn more about the increasing concentrations of greenhouse gases in the atmosphere, visit the Climate Change Indicators: Atmospheric Concentrations of Greenhouse Gases page.
Each of these gases can remain in the atmosphere for different amounts of time, ranging from a few years to thousands of years. All of these gases remain in the atmosphere long enough to become well mixed, meaning that the amount that is measured in the atmosphere is roughly the same all over the world, regardless of the source of the emissions.
Some gases are more effective than others at making the planet warmer and "thickening the Earth's blanket. For each greenhouse gas, a Global Warming Potential GWP has been calculated to reflect how long it remains in the atmosphere, on average, and how strongly it absorbs energy. Note: All emission estimates are from the Inventory of U.
Greenhouse Gas Emissions and Sinks: — Carbon dioxide CO 2 is the primary greenhouse gas emitted through human activities. In , CO 2 accounted for about 80 percent of all U.
Carbon dioxide is naturally present in the atmosphere as part of the Earth's carbon cycle the natural circulation of carbon among the atmosphere, oceans, soil, plants, and animals. Human activities are altering the carbon cycle—both by adding more CO 2 to the atmosphere, and by influencing the ability of natural sinks, like forests and soils, to remove and store CO 2 from the atmosphere. While CO 2 emissions come from a variety of natural sources, human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution.
Carbon dioxide is constantly being exchanged among the atmosphere, ocean, and land surface as it is both produced and absorbed by many microorganisms, plants, and animals. However, emissions and removal of CO 2 by these natural processes tend to balance, absent anthropogenic impacts.
Since the Industrial Revolution began around , human activities have contributed substantially to climate change by adding CO 2 and other heat-trapping gases to the atmosphere. In the United States, since , the management of forests and other land e.
This carbon sink offset is about 12 percent of total emissions in and is discussed in more detail in the Land Use, Land-Use Change, and Forestry section.
To find out more about the role of CO 2 in warming the atmosphere and its sources, visit the Climate Change Indicators page. Carbon dioxide emissions in the United States increased by about 3 percent between and Since the combustion of fossil fuel is the largest source of greenhouse gas emissions in the United States, changes in emissions from fossil fuel combustion have historically been the dominant factor affecting total U.
Changes in CO 2 emissions from fossil fuel combustion are influenced by many long-term and short-term factors, including population growth, economic growth, changing energy prices, new technologies, changing behavior, and seasonal temperatures. Between and , the increase in CO 2 emissions corresponded with increased energy use by an expanding economy and population, including overall growth in emissions from increased demand for travel.
The most effective way to reduce CO 2 emissions is to reduce fossil fuel consumption. Many strategies for reducing CO 2 emissions from energy are cross-cutting and apply to homes, businesses, industry, and transportation. Improving the insulation of buildings, traveling in more fuel-efficient vehicles, and using more efficient electrical appliances are all ways to reduce energy use, and thus CO 2 emissions. Reducing personal energy use by turning off lights and electronics when not in use reduces electricity demand.
Reducing distance traveled in vehicles reduces petroleum consumption. Both are ways to reduce energy CO 2 emissions through conservation. Producing more energy from renewable sources and using fuels with lower carbon contents are ways to reduce carbon emissions. Carbon dioxide capture and sequestration is a set of technologies that can potentially greatly reduce CO 2 emissions from new and existing coal- and gas-fired power plants, industrial processes, and other stationary sources of CO 2.
For example, capturing CO 2 from the stacks of a coal-fired power plant before it enters the atmosphere, transporting the CO 2 via pipeline, and injecting the CO 2 deep underground at a carefully selected and suitable subsurface geologic formation, such as a nearby abandoned oil field, where it is securely stored.
Some of the excess carbon dioxide will be absorbed quickly for example, by the ocean surface , but some will remain in the atmosphere for thousands of years, due in part to the very slow process by which carbon is transferred to ocean sediments.
Qin, G. Plattner, M. The scientific consensus, as stated by the Intergovernmental Panel on Climate Change , is that greenhouse gases, which are increasing because of human activities, are trapping heat in the atmosphere. To better understand the formation and composition of Earth, scientists sometimes compare our planet with Venus and Mars.
All three of these planets are rocky in nature and are part of the inner solar system, meaning that they are in between the sun and the asteroid belt. Venus has an almost fully carbon dioxide atmosphere , with traces of nitrogen and sulfuric acid. The planet, however, also has a runaway greenhouse effect on its surface. Spacecraft have to be heavily reinforced to survive the crushing pressure 90 times heavier than Earth , and the oven-like temperatures Fahrenheit or Celsius , found at its surface.
The clouds are also so thick that the surface is invisible in visible light. Because not much sun reaches the surface, this means that Venus has no significant seasonal temperature changes. Mars also has a mostly carbon dioxide atmosphere , with traces of nitrogen, argon, oxygen, carbon monoxide and some other gases. On this planet, the atmosphere is about times thinner than Earth's — a very different situation from the ancient past, when geological evidence shows that water used to flow on the surface more than 4.
Scientists suggest that the Martian atmosphere may have thinned over time, either because the sun stripped away the lighter molecules in the atmosphere, or because a huge impact by an asteroid or comet catastrophically stripped the atmosphere. Mars undergoes temperature swings influenced by how much sunlight reaches the surface, which also affects its polar ice caps another great influence on the atmosphere.
Scientists routinely compare small, rocky exoplanets to Earth, Venus and Mars to get a better sense of their habitability. The routinely accepted definition of "habitability" is that a planet is close enough to the star for liquid water to exist on its surface. Too far, and the water turns icy; too close, and the water evaporates.
However, habitability not only depends on the star-planet distance, but also the planet's atmosphere, the star's variability, and other factors. Additional reporting by Space. This article was updated July 20, by Space. Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community space. Jump to: What's air made of?
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