How is greenhouse gases caused

Agriculture, forestry and other land use Agriculture, deforestation and other changes in land use account for one quarter of net anthropogenic greenhouse gas emissions. The main sources of emissions are: feed production and processing 45 per cent outputs of greenhouse gases during digestion by cows 39 per cent manure decomposition 10 per cent The rest is attributable to the processing and transportation of animal products.

Cement manufacture Cement manufacture contributes CO 2 to the atmosphere when calcium carbonate is heated, producing lime and CO 2. A cement works in Clitheroe. The cement industry produces around five per cent of global anthropogenic CO2 emissions. Aerosols Aerosols are small particles suspended in the atmosphere that can be produced when we burn fossil fuels. Volcanic ash dunes of Tarvurvur, Papua New Guinea. Sea salt, dust and volcanic ash are three common types of aerosols.

Aerosols directly scatter and absorb radiation. The scattering of radiation causes atmospheric cooling, whereas absorption can cause atmospheric warming.

You may also be interested in. Discovering Geology Discovering Geology introduces a range of geoscience topics to school-age students and learners of all ages. Climate change Climate is the pattern of weather of an area averaged over many years. Impacts of climate change Temperature rises can affect agriculture, sea levels and the frequency of extreme weather incidents.

The carbon story The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere into the Earth, then released back into the atmosphere. Understanding carbon capture and storage Carbon capture and storage involves capturing carbon dioxide at emission sources, such as power stations, then transporting and storing it underground. What are we doing about climate change?

CO 2 occurs naturally in the atmosphere as part of the Earth's carbon cycle — the natural circulation of carbon among the air, water and ecosystems.

Human activities are altering the carbon cycle either by adding CO 2 to the atmosphere or by influencing the ability of natural sinks to remove CO 2 from the atmosphere. Burning of fossil fuels coal, oil, natural gas and wood are the primary source of human-caused CO 2 emissions. Natural sinks are affected by deforestation and other land use changes.

According to IPCC, human-caused greenhouse gas emissions have increased since the pre-industrial era and are now higher than ever.

Between and , about half of the emissions have occurred in the last 40 years. The rest has been removed from the atmosphere and stored on land in plants and soils, and in the oceans. However, it is not clear how effectively these CO 2 sinks will operate in the future under a changing climate and increasing human impacts.

Methane is emitted by natural and human sources. The main natural sources of methane include wetlands, tundra, oceans and their bottom sediments, and termites. Important human sources include landfills, livestock farming especially enteric fermentation in farm animals , rice farming, biomass burning, as well as the production, transportation and use of fossil fuels.

Although there is a relatively small amount of N 2 O in the atmosphere, its lifetime is long, about years, which makes it very important for the total amount of global greenhouse gases.

N 2 O has nearly times the global warming potential of carbon dioxide. The nitrous oxide levels are now higher than ever in the past , years.

Nitrous oxide emissions are produced by both natural and human sources. The major natural sources include soils under natural vegetation, tundra and the oceans. Important human sources come from agriculture nitrous oxide fertilizers, soil cultivation , livestock manure, biomass or fossil fuels combustion and industrial processes. In total, over one third of the emissions are estimated to come from human actions.

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. Building public transportation, sidewalks, and bike paths to increase lower-emission transportation choices.

Zoning for mixed use areas, so that residences, schools, stores, and businesses are close together, reducing the need for driving.

Upgrading to more efficient industrial technology. Identifying the ways that manufacturers can use less energy to light and heat factories or to run equipment. Switching to fuels that result in less CO 2 emissions but the same amount of energy, when combusted.

Producing industrial products from materials that are recycled or renewable, rather than producing new products from raw materials. Making companies and workers aware of the steps to reduce or prevent emissions leaks from equipment. EPA has a variety of voluntary programs that provide resources for training and other steps for reducing emissions. EPA supports programs for the aluminum , semiconductor , and magnesium industries.

Instituting handling policies and procedures for perfluorocarbons PFCs , hydrofluorocarbons HFCs , and sulfur hexafluoride SF 6 that reduce occurrences of accidental releases and leaks from containers and equipment.

Homes and commercial buildings use large amounts of energy for heating, cooling, lighting, and other functions. Techniques to improve building energy efficiency include better insulation; more energy-efficient heating, cooling, ventilation, and refrigeration systems; efficient fluorescent lighting; passive heating and lighting to take advantage of sunlight; and the purchase of energy-efficient appliances and electronics.

Drinking water and wastewater systems account for approximately 2 percent of energy use in the United States. By incorporating energy efficiency practices into their water and wastewater plant, municipalities and utilities can save 15 to 30 percent in energy use.

Reducing solid waste sent to landfills. Capturing and using methane produced in current landfills. Landfill gas is the natural byproduct of the decomposition of solid waste in landfills. It primarily consists of CO 2 and CH 4. Well established, low-cost methods to reduce greenhouse gases from consumer waste exist, including recycling programs, waste reduction programs, and landfill methane capture programs.

Reducing leakage from air conditioning and refrigeration equipment. Using refrigerants with lower global warming potentials. Indeed, studies show that solar variability has played a role in past climate changes. For example, a decrease in solar activity coupled with an increase in volcanic activity is thought to have helped trigger the Little Ice Age between approximately and , when Greenland cooled from to the s and glaciers advanced in the Alps.

But several lines of evidence show that current global warming cannot be explained by changes in energy from the Sun:. Not enough greenhouse effect: The planet Mars has a very thin atmosphere, nearly all carbon dioxide. Because of the low atmospheric pressure, and with little to no methane or water vapor to reinforce the weak greenhouse effect, Mars has a largely frozen surface that shows no evidence of life.

Too much greenhouse effect: The atmosphere of Venus, like Mars, is nearly all carbon dioxide. But Venus has about , times as much carbon dioxide in its atmosphere as Earth and about 19, times as much as Mars does , producing a runaway greenhouse effect and a surface temperature hot enough to melt lead.

The above graph compares global surface temperature changes red line and the Sun's energy that Earth receives yellow line in watts units of energy per square meter since Eleven-year averages are used to reduce the year-to-year natural noise in the data, making the underlying trends more obvious.

Over the same period, global temperature has risen markedly.