The effect of each greenhouse gas on the Earth`s climate depends on its chemical nature and relative concentration in the atmosphere. Some gases have a high capacity to absorb infrared radiation or occur in significant quantities, while others have much lower absorption capacities or occur only in trace amounts. Radiative forcing, as defined by the Intergovernmental Panel on Climate Change (IPCC), is a measure of the influence of a particular greenhouse gas or other climatic factor (such as solar radiation or albedo) on the amount of radiant energy hitting the Earth`s surface. In order to understand the relative influence of each greenhouse gas, the so-called forcing values (in watts per square meter) for the period between 1750 and today are given below. Methane from manure management practices can be reduced and captured by modifying manure management strategies. In addition, changes in animal feeding practices can reduce emissions from enteric fermentation. Learn more about improving manure management practices through the EPA`s AgSTAR program. We were also a key partner at COP26, the 2021 Global Climate Change Summit, where governments around the world reported on their countries` progress in tackling climate change and agreed on new measures to reduce carbon emissions. Sulfur hexafluoride is an extremely potent greenhouse gas used in the transmission of electricity through the power grid for various purposes. EPA works with industry to reduce emissions through the SF6 Emission Reduction Partnership for Electric Power Systems, which promotes leak detection and repair, the use of recycling equipment, and employee training. The respective influence of CO2, CH4 and N2O on climate varies.
Thus, CH4 and N2O have a disproportionate influence on the greenhouse effect compared to their relatively low atmospheric concentrations. The most abundant greenhouse gases in Earth`s atmosphere, listed in descending order of the average global mole, are:[15][16] This is exactly how greenhouse gases work. They let sunlight pass through the atmosphere, but they prevent the heat that sunlight brings from leaving the atmosphere. Overall, greenhouse gases are a good thing. Without them, our planet would be too cold and life as we know it would not exist. But there can be too many good things. Scientists are concerned that human activities are injecting too much of these gases into the atmosphere. There are several ways to reduce CH4 emissions. Some examples are explained below. The EPA has a number of voluntary programs to reduce CH4 emissions, in addition to regulatory initiatives. EPA also supports the Global Methane Initiative, an international partnership that promotes global methane reduction strategies. A number of processes influence the concentration of greenhouse gases.
Some, such as tectonic activity, operate on timescales of millions of years, while others, such as vegetation, soil, wetlands, and marine springs and sinks, operate on time scales ranging from hundreds to thousands of years. Human activities – particularly the burning of fossil fuels since the Industrial Revolution – are responsible for the steady increase in atmospheric concentrations of various greenhouse gases, particularly carbon dioxide, methane, ozone and chlorofluorocarbons (CFCs). The global warming potential (GWP) depends on both the effectiveness of the molecule as a greenhouse gas and its atmospheric lifetime. GWP is measured against the same CO2 mass and evaluated on a specific time scale. [40] Thus, if a gas has a high radiative forcing (positive) but also a short lifespan, it has a large GWP on a 20-year scale, but a small one on a 100-year scale. Conversely, if a molecule has a longer atmospheric lifetime than CO2, its GWP increases when the time scale is taken into account. Carbon dioxide is defined as a GWP of 1 over all time periods. In addition to these trace gases, which occur only in very low concentrations in the atmosphere, water vapour is probably the most important greenhouse gas. However, it only plays a major role in relation to the natural greenhouse effect, since the ability to absorb water vapor in the air is directly related to temperature. Water vapour therefore has little influence on human-induced climate change.
A number of natural and man-made mechanisms can influence the global energy balance and force changes in the Earth`s climate. Greenhouse gases are one such mechanism. Greenhouse gases absorb and emit some of the energy radiated by the Earth`s surface, trapping this heat in the lower atmosphere. [46] As explained above, some greenhouse gases remain in the atmosphere for decades or even centuries and can therefore affect the Earth`s energy balance over a long period of time. Radiative forcing quantifies (in watts per square metre) the effect of factors influencing the Earth`s energy balance; including changes in greenhouse gas concentrations. Positive radiative forcing leads to heating by increasing net influx energy, while negative radiative forcing leads to cooling. [47] Greenhouse gases are gases that can trap heat. They get their name from greenhouses. A greenhouse is full of windows that let in sunlight. This sunlight generates heat. The big thing about a greenhouse is that it doesn`t allow that heat to escape. In addition to the major greenhouse gases listed above, other greenhouse gases include sulphur hexafluoride, hydrofluorocarbons and perfluorocarbons (see IPCC list of greenhouse gases).