As a hydrocarbon , it can undergo hydrocarbon combustion which gives off heat. Methane is the main hydrocarbon component of natural gas , which is a type of fossil fuel. It has a shorter atmospheric lifetime than CO 2 , at 12 years, [4] but this is "balanced" by the fact that it is more effective at trapping heat than CO 2 , as methane has a GWP Global warming potential of Methane combustion see simulation at bottom of page provides a significant fraction of the world's primary energy , and is used for home heating , cooking food, heating water , and electrical generation.
It can even provide energy for transportation. The impact of 1 pound of N 2 O on warming the atmosphere is almost times that of 1 pound of carbon dioxide. Nitrous oxide emissions occur naturally through many sources associated with the nitrogen cycle, which is the natural circulation of nitrogen among the atmosphere, plants, animals, and microorganisms that live in soil and water.
Nitrogen takes on a variety of chemical forms throughout the nitrogen cycle, including N 2 O. Natural emissions of N 2 O are mainly from bacteria breaking down nitrogen in soils and the oceans. Nitrous oxide is removed from the atmosphere when it is absorbed by certain types of bacteria or destroyed by ultraviolet radiation or chemical reactions.
To find out more about the sources of N 2 O and its role in warming the atmosphere, visit the Climate Change Indicators page. Nitrous oxide emissions in the United States have remained relatively flat between and Nitrous oxide emissions from mobile combustion decreased by 60 percent from to as a result of emission control standards for on-road vehicles.
Nitrous oxide emissions from agricultural soils have varied during this period and were about 9 percent higher in than in , primarily driven by increasing use of nitrogen fertilizers. The application of nitrogen fertilizers accounts for the majority of N 2 O emissions in the United States.
Emissions can be reduced by reducing nitrogen-based fertilizer applications and applying these fertilizers more efficiently, 3 as well as modifying a farm's manure management practices. Additionally, the introduction of pollution control technologies e.
Production of adipic acid results in N 2 O emissions that can be reduced through technological upgrades. Greenhouse Gas Mitigation Potential in U.
Forestry and Agriculture. Unlike many other greenhouse gases, fluorinated gases have no natural sources and only come from human-related activities. They are emitted through their use as substitutes for ozone-depleting substances e.
Many fluorinated gases have very high global warming potentials GWPs relative to other greenhouse gases, so small atmospheric concentrations can have disproportionately large effects on global temperatures.
They can also have long atmospheric lifetimes—in some cases, lasting thousands of years. Like other long-lived greenhouse gases, most fluorinated gases are well-mixed in the atmosphere, spreading around the world after they are emitted.
Many fluorinated gases are removed from the atmosphere only when they are destroyed by sunlight in the far upper atmosphere. In general, fluorinated gases are the most potent and longest lasting type of greenhouse gases emitted by human activities. The largest sources of fluorinated gas emissions are described below.
To find out more about the role of fluorinated gases in warming the atmosphere and their sources, visit the Fluorinated Greenhouse Gas Emissions page. Overall, fluorinated gas emissions in the United States have increased by about 86 percent between and This increase has been driven by a percent increase in emissions of hydrofluorocarbons HFCs since , as they have been widely used as a substitute for ozone-depleting substances.
Emissions of perfluorocarbons PFCs and sulfur hexafluoride SF 6 have actually declined during this time due to emission reduction efforts in the aluminum production industry PFCs and the electricity transmission and distribution industry SF 6.
Because most fluorinated gases have a very long atmospheric lifetime, it will take many years to see a noticeable decline in current concentrations. However, there are a number of ways to reduce emissions of fluorinated gases, described below. Refrigerants used by businesses and residences emit fluorinated gases.
Emissions can be reduced by better handling of these gases and use of substitutes with lower global warming potentials and other technological improvements. Industrial users of fluorinated gases can reduce emissions by adopting fluorinated gas recycling and destruction processes, optimizing production to minimize emissions, and replacing these gases with alternatives.
EPA has experience with these gases in the following sectors:. Sulfur hexafluoride is an extremely potent greenhouse gas that is used for several purposes when transmitting electricity through the power grid. EPA is working with industry to reduce emissions through the SF 6 Emission Reduction Partnership for Electric Power Systems , which promotes leak detection and repair, use of recycling equipment, and employee training. Over all, about a third of all the methane floating in the modern atmosphere comes from wetlands.
There are a variety of other natural methane sources. It seeps out of the ground naturally near some oil and gas deposits and from the mouths of some volcanoes. It leaks out of thawing permafrost in the Arctic and builds up in the sediments under shallow, still seas; it wafts away from burning landscapes, entering the atmosphere as CO 2 ; and it is produced by termites as they chow through piles of woody detritus.
But all of these other natural sources, excluding wetlands, only make up about ten percent of the total emissions each year. Cows and other grazing animals get a lot of attention for their methane-producing belches and releases. Such grazers host microbes in their stomachs, gut-filling hitchhikers that help them break down and absorb the nutrients from tough grasses. Those microbes produce methane as their waste, which wafts out of both ends of cows. The manure that cattle and other grazers produce is also a site for microbes to do their business, producing even more methane.
There are 1. Other agricultural endeavors pump methane into the atmosphere, too. And some scientists think they can see the moment when rice production took off in Asia, about 5, years ago, because methane concentrations—recorded in tiny bubbles of ancient air trapped in ice cores in Antarctica—rose rapidly.
Methane also leaks into the atmosphere at gas and oil drilling sites. There are strict rules in place in many states and countries about how much leakage is allowed, but those rules have proven difficult to enforce. Recent studies suggest that wells in the U. Worldwide, the energy sector contributes about a quarter of the annual methane budget.
The gas is also a significant contributor to climate change. In , methane accounted for roughly 10 percent of all human-driven greenhouse gas emissions in the U. First, methane can be produced through a series of chemical reactions as organic matter is decomposed at shallow depths in low-oxygen environments, such as swamps and bogs.
As plants die and sink to the bottom of these watery environments, bacteria starts to break them down. According to a study in the Proceedings of the National Academy of Sciences , wetlands are the single largest natural contributor to methane emissions. Additionally, methane can leak from mud volcanoes, rice fields, and strangely, termites.
Methane can also be found in underground fossil fuel deposits that have been subjected to high pressure and temperatures over millions and millions of years. As these fuels are harvested, mined, and released, so is methane. Methane is difficult to transport and easily leaks during the extraction of oil, coal, and natural gas —hence the regulations.
A form of methane mixed with ice, called methane gas hydrates, can be found trapped in layers of sediment on the ocean floor and beneath permafrost and frozen lakes in the Arctic.
These solid, ice-like deposits have been touted as a potential energy source, but are particularly troubling because they can release large concentrated amounts of methane into the atmosphere. According to the EPA , roughly 50 to 65 percent of U. About 27 percent of methane emissions are generated through a process called enteric fermentation—cows burping and occasionally farting while they digest their food, basically—and 16 percent of global methane emissions are generated by organic waste decomposing in landfills.
Methane can be also be released through the storage and use of manure for fuel 9 percent and through coal mining 8 percent.
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