How many greenhouse gases exist

And our choice of metric can have an impact on how we prioritise GHG reduction strategies: do we first target strong but short-lived gases such as methane? This may slow warming in the short-term — a reasonable argument if we are concerned about approaching temperature-induced tipping points. Or do we focus instead on the persistent CO 2 emissions which will be the primary driver of long-term temperature impacts?

Some researchers have developed new methods which aim to provide a closer representation of the actual temperature response to different gases. Scenarios b and c are very different to CO 2 , as rapidly or gradually decreasing CO 2 emissions leads to further global temperature increases only the rate of temperature increase slows.

As we discussed in previous sections, greenhouse gases vary in their relative contributions to global warming; i. In the chart we see the GWP value of key greenhouse gases relative to carbon dioxide. The GWP metric measures the relative warming impact one molecule or unit mass of a greenhouse gas relative to carbon dioxide over a year timescale. For example, one tonne of methane would have 28 times the warming impact of tonne of carbon dioxide over a year period.

GWP values are used to combine greenhouse gases into a single metric of emissions called carbon dioxide equivalents CO 2 e. CO 2 e is derived by multiplying the mass of emissions of a specific greenhouse gas by its equivalent GWP factor. The sum of all gases in their CO 2 e form provide a measure of total greenhouse gas emissions. You might notice that our estimates of total greenhouse gas emissions are not available on the long-term timescales we have for CO 2 emissions. In our work on CO 2 we have global, regional and country estimates extending back centuries — all the way back to For total greenhouse gases we only have this data back to CO 2 emissions from fossil fuels and industry are — in comparison to other greenhouse gases — easier to estimate.

Most of our CO 2 emissions come from the burning of coal, oil and gas for energy. At the country, regional and global level we have good data or can provide reasonable approximations of the quantity of energy produced, and the sources of this energy.

We can approximate how much coal, oil and gas is burned every year. We know how much CO 2 is emitted when we produce a unit from a fuel source for example, a kilowatt-hour from coal. In our work on CO 2 emissions we discuss in more detail how long-term emissions are calculated. But estimating emissions of other greenhouse gases is more difficult. You will notice that data on methane and nitrous oxide emissions only date back to But it has only very recently published its first Methane Budget published in , and at time of publication its first N 2 O budget is not yet available.

A large share of methane and nitrous oxide emissions come from agriculture, land use and waste. Getting accurate data for all countries, and extending back centuries on the emissions from livestock, soils and different land types is much more difficult.

Even if we know how much food is produced from agriculture, and we have standard emissions factors of how much greenhouse gases are emitted per unit of food for example, per kilogram of rice , this can vary a lot depending on the location, soil type and specific farming practices. We explored this in detail in our article on the differences in the emissions of different food types: depending on the production system, beef in one location can emit more than 10 times as much as beef produced elsewhere.

So, unlike CO 2 from energy, emissions factors for agriculture and land use can be highly variable. This makes it difficult to estimate long-term emissions for methane and nitrous oxide and other greenhouse gases which exist in lower concentrations. As a result, estimates of total greenhouse gas emissions are only available on shorter timescales, and often not at the same resolution as CO 2 data.

Total greenhouse gas emissions. Global greenhouse gas emissions. Click PDF to download a printable version:. The Greenhouse Effect The greenhouse effect is a natural phenomenon that insulates the Earth from the cold of space. Its concentration depends on temperature and other meteorological conditions and not directly upon human activities.

CO 2 is used as the reference gas and has a GWP of one. Iron and steel production, cement production and petrochemical production are other significant sources of CO 2 emissions.

Support a strong clean fuel standard. This will help advance low-carbon fuel sources like biofuels and electrification. Did you know? Methane is produced naturally when vegetation is burned, digested or rotted without oxygen. Oil and gas production, cattle farming, waste dumps and rice farming release large amounts of methane. Nitrous oxide , released by chemical fertilizers and burning fossil fuels, has a global warming potential times that of carbon dioxide.

Join us on social! Learn more about climate change and discover ways to take action. What you can do View all. Climate change basics. Sources of Greenhouse Gas Emissions. Electricity Sector Emissions. Transportation Sector Emissions. Inventory's section on Fossil Fuel Combustion. Industry Sector Emissions.

Commercial and Residential Sector Emissions. Agriculture Sector Emissions. Land Use, Land-Use Change, and Forestry Sector Emissions and Sequestration Plants absorb carbon dioxide CO 2 from the atmosphere as they grow, and they store some of this carbon as aboveground and belowground biomass throughout their lifetime.

More national-level information about land use, land-use change, and forestry is available from the Land Use, Land-Use Change, and Forestry chapter in the Inventory of U. For more information on emissions and sequestration from forest land and urban trees in settlement areas, see also the USFS Resource Update.

An Explanation of Units A million metric tons is equal to about 2. Contact Us to ask a question, provide feedback, or report a problem. Increasing the efficiency of existing fossil fuel-fired power plants by using advanced technologies; substituting less carbon-intensive fuels; shifting generation from higher-emitting to lower-emitting power plants.

Converting a coal-fired boiler to use of natural gas, or co-firing natural gas. Converting a single-cycle gas turbine into a combined-cycle turbine.

Shifting dispatch of electric generators to lower-emitting units or power plants. Increasing the share of total electricity generated from wind, solar, hydro, and geothermal sources, as well as certain biofuel sources, through the addition of new renewable energy generating capacity.

Reducing electricity use and peak demand by increasing energy efficiency and conservation in homes, businesses, and industry. Capturing CO 2 as a byproduct of fossil fuel combustion before it enters the atmosphere, transporting the CO 2 , injecting the CO 2 deep underground at a carefully selected and suitable subsurface geologic formation where it is securely stored.

Capturing CO 2 from the stacks of a coal-fired power plant and then transferring the CO 2 via pipeline, injecting the CO 2 deep underground at a carefully selected and suitable nearby abandoned oil field where it is securely stored. Learn more about CCS. Using fuels that emit less CO 2 than fuels currently being used. Alternative sources can include biofuels; hydrogen; electricity from renewable sources, such as wind and solar; or fossil fuels that are less CO 2 -intensive than the fuels that they replace.

Using public buses that are fueled by compressed natural gas rather than gasoline or diesel. Using electric or hybrid automobiles, provided that the energy is generated from lower-carbon or non-fossil fuels. Using renewable fuels such as low-carbon biofuels. Using advanced technologies, design, and materials to develop more fuel-efficient vehicles. Learn about EPA's vehicle greenhouse gas rules. Developing advanced vehicle technologies such as hybrid vehicles and electric vehicles, that can store energy from braking and use it for power later.

Reducing the weight of materials used to build vehicles. Reducing the aerodynamic resistance of vehicles through better shape design. Adopting practices that minimize fuel use. Improving driving practices and vehicle maintenance. Reducing the average taxi time for aircraft. Driving sensibly avoiding rapid acceleration and braking, observing the speed limit.

Reducing engine-idling. Improved voyage planning for ships, such as through improved weather routing, to increase fuel efficiency. Employing urban planning to reduce the number of miles that people drive each day. Reducing the need for driving through travel efficiency measures such as commuter, biking, and pedestrian programs.