Green house effect & Global warming

Green House effect & Global Warming

• Global Warming is defined as the increase of the average temperature on Earth.

• The phenomenon of heat build-up inside a glass chamber from the absorption of solar radiation is called greenhouse effect.

Types of Greenhouse Effect -

1. The Natural Greenhouse Effect

• The greenhouse effect is the rise in temperature that the Earth experiences because certain gases which are present naturally in the atmosphere.

• For example-water vapor, carbon dioxide, nitrous oxide, ozone, methane.

2. The Enhanced Greenhouse Effect

• Greenhouse gases are continuously accumulating in the atmosphere due to certain human activities.

• The change in the balance of the greenhouse gases has significant effects on the entire planet and known as enhanced greenhouse effect.

Process of Greenhouse effect and global warming

• The Earth receives solar radiation, a portion of which is deflected by the atmosphere and returns to space, while the remainder penetrates the atmosphere and reaches the surface.

• About half of these are absorbed by the atmosphere and heat the air.

• The rest reaches the earth’s surface. The earth’s surface now heats up and gives off longer wavelength, lower energy (infra-red or heat) radiations.

• These infra-red radiations pass back up into the atmosphere.

• A significant portion of the radiation that enters the Earth's atmosphere is not immediately reflected back into space, but instead, it is absorbed and re-emitted back to the Earth's surface.

• The temperature near the earth’s surface as well as that of the atmosphere then rises.

Greenhouse gases

1. Carbon Dioxide

Sources-

• Fossil Fuel Combustion.

• Forest fires.

• Animal respiration.

• Plant degradation.

Sinks-

• Photosynthesis by green plants.

• Photosynthesis by phytoplankton as well as dissolution.

• Carbonate-forming reactions of many marine organisms. 

2.Methane

• Chemical reactions involving CH4 in the troposphere can lead to ozone production, and reaction with the hydroxyl radical (OH) in the stratosphere results in the production of water vapor.

• Both tropospheric ozone , especially in the upper troposphere , and stratospheric water vapor are significant greenhouse gases.

• The final oxidation product of CH4 is CO2 which is also a greenhouse gas.

Sources-

Natural

• Wetlands(maximum).

• Ocean.

• Freshwater.

  Anthropogenic

• Coal Mining, Natural Gas& Pet. Industry.

• Rice Paddies.

• Enteric Fermentation.

• Animal Wastes.

• Biomass burning.

• Land fills.

Sinks

• Atmospheric (tropospheric +stratospheric) removal.

• Removal by soils.

 3.Nitrous Oxide (N2O)

• Nitrous oxide is an important long-lived greenhouse gas.

• It is the primary source of the oxides of nitrogen in the stratosphere.

Note- NO and NO2 are global coolant (not greenhouse gases)

Sources-

Natural

• Oceans.

• Tropical Soils.

• Wet forests.

• Dry savannas.

• Grasslands.

Anthropogenic

• Biomass Burning.

• Cultivated.

Sinks

• Removal by soils.

• Photolysis in the Stratosphere.

4.Ozone

• Ozone, commonly known as O3, performs a crucial role in the absorption of solar ultraviolet radiation. It is also an influential greenhouse gas in the lower stratosphere and upper troposphere.

• About 90% of the total column of ozone resides in the stratosphere, and the remaining 10% in the troposphere

5.Water vapor

• Water vapor is the biggest overall contributor to the greenhouse effect.

• In the warm and wet tropics, it may account for four per cent of the air by volume, while in the dry and cold areas of desert and polar regions, it may be less than one per cent of the air.

• It is largest contributor of greenhouse effect as it absorbs both incoming and outgoing radiation.

6.Black Carbon

• Black carbon is a significant worldwide environmental issue that has adverse effects on human health and the climate.
• Soot, also known as black carbon, is a small particle created through the inadequate combustion of fossil fuels, biofuels, and biomass.
• Black carbon remains in the atmosphere for a brief period, ranging from a few days to weeks.

Sources

• Open biomass burning.

• Residential biomass burned with traditional technologies.

• Diesel engines for transportation.

• Industrial processes and power generation.

Impacts

• Particulate matter is considered the most dangerous air pollutant that poses a significant risk to public health.
• Black carbon particles present in the atmosphere directly absorb sunlight, leading to a reduction in planetary albedo.
• The presence of black carbon particles in the air can contribute to global warming and climate change, in addition to negatively impacting human health.

• Black carbon absorb incoming solar radiation, perturb the temperature structure of the atmosphere, and influence cloud cover.

• The presence of black carbon over highly reflective surfaces, such as snow and ice, or clouds, may cause a significant positive radiative forcing (change in energy flux in atmosphere).

7.Brown Carbon

• Brown carbon is a common yet unidentified organic aerosol component.
• Studies have indicated that biomass burning is a significant contributor to brown carbon.
• Brown carbon can have important impacts on climate and air quality.
• Despite its importance, brown carbon remains poorly understood and difficult to measure.
• Further research is necessary to fully understand the sources and effects of brown carbon in the atmosphere.

8.Fluorinated gases

 A. Chlorofluorocarbons (CFCs)

• CFCs were phased out via the Montreal Protocol due to their part in ozone depletion but This anthropogenic compound is also a greenhouse gas, with a much higher potential to enhance the greenhouse effect than CO₂.

B. Hydrofluorocarbons

• HFCs are potent greenhouse gases that have a long lifespan in the atmosphere.
• They have various industrial applications such as refrigerants, solvents, aerosol propellants, and fire retardants.
• Hydrofluorocarbons were created as a substitute for CFCs and HCFCs as they do not contribute to the depletion of the ozone layer in the stratosphere.

C. Perfluorocarbons

• Perfluorocarbons (PFCs) are chemical compounds that are produced as by-products during the manufacturing of semiconductors and in the production of aluminum.
• Similar to hydrofluorocarbons (HFCs), PFCs tend to have long atmospheric lifetimes and a high global warming potential.
• PFCs are a type of greenhouse gas that can contribute to climate change and are regulated under the United Nations Framework Convention on Climate Change (UNFCCC).
• The use of PFCs is limited and regulated by various international agreements, such as the Montreal Protocol and the Kyoto Protocol.

D. Sulphur hexafluoride

• Sulphur hexafluoride is also a greenhouse gas.

• Sulfur hexafluoride finds application in various industries, including magnesium processing and semiconductor manufacturing. Additionally, it is utilized as a tracer gas for detecting leaks.

• Sulphur hexafluoride is used in electrical transmission equipment, including circuit breakers.

E. Sulphur-Containing Gases

• Sulphur-containing gases emitted into the atmosphere through natural and anthropogenic processes affect the Earth's radiative budget by being transformed into sulphate aerosol particles that scatter sunlight back to space.

• Thereby reducing the radiation reaching the Earth's surface possibly increase the number of cloud condensation nuclei, thereby potentially altering the physical characteristics of clouds affect atmospheric chemical composition, e.g., stratospheric O3, by providing surfaces for heterogeneous chemical processes

Global Warming Potential

• Global warming potential describes the impact of each gas on global warming.

• The Global Warming Potential (GWP) is a metric used to measure the total amount of energy that a gas can absorb over a specific period, typically 100 years, when compared to carbon dioxide.
• A gas with a higher GWP can absorb more energy compared to carbon dioxide.
• The GWP is an essential tool for evaluating the potential climate impact of different greenhouse gases and is commonly used in climate change research and policy-making.

GWP-

• Carbon dioxide -1.

• Methane - 21.

• Nitrous oxide - 310.

• Hydro fluorocarbons (HFCs) - 140-11,700.

• Perfluorocarbons (PFCs) - 6,500-9,200.

• Sulfur hexafluoride (SF6) - 23,900.

Years for which they can remain alive

• Carbon dioxide -100.

• Methane - 12.

• Nitrous oxide - 120.

• Hydro fluorocarbons (HFCs) - 1-270.

• Perfluorocarbons (PFCs) – 800-50000.

• Sulfur hexafluoride (SF6) – 3200.

Facts-

• Sulfur hexafluoride (SF6) have maximum global warming potential.

• Sulfur hexafluoride (SF6) and perfluoro carbon have maximum lifetime.

Important One Liner Questions and Answers on Green house gases and Global Warming.

What is global warming?

A rise in the Earth's average temperature.

What is the greenhouse effect?

Heat build-up inside a glass chamber from the absorption of solar radiation.

What are the types of greenhouse effect?

Natural and Enhanced greenhouse effect.

Which gases contribute to the greenhouse effect?

Water vapor, carbon dioxide, nitrous oxide, ozone, methane.

What is the process of the greenhouse effect and global warming?

Greenhouse gases trap heat from the sun, causing the temperature to rise on Earth.

What is carbon dioxide?

A greenhouse gas released from fossil fuel combustion, forest fires, animal respiration, and plant degradation.

What are the sources of methane?

Coal mining, natural gas and petroleum industry, rice paddies, enteric fermentation, animal wastes, biomass burning, and landfills.

What is the primary source of oxides of nitrogen in the stratosphere?

Nitrous oxide.

Which gas is considered as the most significant contributor to the greenhouse effect?

Water vapor.

What is black carbon?

A small particle created through the inadequate combustion of fossil fuels, biofuels, and biomass.

What is the impact of black carbon?

Absorb incoming solar radiation, cause a reduction in planetary albedo, and contribute to global warming and climate change.

What is brown carbon?

An unidentified organic aerosol component.

What are the sources of brown carbon?

Biomass burning.

What is the impact of brown carbon?

It can have important impacts on climate and air quality.

What are fluorinated gases?

Anthropogenic compounds that are greenhouse gases.

What are Chlorofluorocarbons (CFCs)?

A greenhouse gas phased out via the Montreal Protocol due to their part in ozone depletion.

What is the sink for carbon dioxide?

Photosynthesis by green plants, phytoplankton, and carbonate-forming reactions of many marine organisms.

What are the sinks for methane?

Atmospheric removal and removal by soils.

What is the role of ozone in the atmosphere?

Crucial role in the absorption of solar ultraviolet radiation and an influential greenhouse gas in the lower stratosphere and upper troposphere.

What is the biggest contributor to the greenhouse effect?

Water vapor.