What do you mean by the Greenhouse effect? What are greenhouse gases? What are global warming and its impact? Read here to know more.
Nowadays we are facing many climate-changing issues like the greenhouse effect and Global Warming.
The greenhouse effect is the way in which heat is trapped close to Earth’s surface by “greenhouse gases.” The greenhouse effect leads to global warming.
What do you mean by the Greenhouse effect?
A greenhouse is a structure where plants that require controlled climate conditions are grown. Its roof and walls are mostly made of transparent material, like glass.
In a greenhouse what is the incident solar radiation?
Visible light and nearby infrared and ultraviolet wavelengths.
Passes through the glass walls and roof and is absorbed by the ground, the floor, and the contents. As the materials warm up, they release the energy as longer-wavelength infrared radiation (heat radiation).
What is the reason infrared radiation cannot escape through radiative transfer?
Because glass and other wall materials used in greenhouses do not transmit infrared energy.
The building is not exposed to the atmosphere, so heat cannot escape through convection, causing the greenhouse’s interior temperature to rise. This is known as the ‘greenhouse effect ‘.
Natural Greenhouse Effect: Importance
The greenhouse effect is a natural occurrence that has been taking place on earth for millions of years.
How natural greenhouse effect caused?
The natural greenhouse effect caused by the presence of water vapour and small water particles in the atmosphere has made life on earth possible. Together, these produce more than 95 per cent of total greenhouse warming.
- Average global temperatures are maintained at about 15°C due to the natural greenhouse effect.
- Without this phenomenon, the world’s average temperature could have been as low as -17°C, where life would not have been able to develop.
Greenhouse Gases (GHGs)
There are multiple gases responsible for the greenhouse effect. They are listed below.
Which gases are responsible for the greenhouse effect?
It is a result of atmospheric gases like carbon dioxide, methane, nitrous oxide (N2O), water vapour, and chlorofluorocarbons being able to trap the outgoing infrared radiation from the earth’s surface.
Hence these gases are known as greenhouse gases and the heating effect is known as the greenhouse effect.
Are all oxides of nitrogen greenhouse gas? No
Oxides of Nitrogen with the general formula NOx – NO, NO2 – Nitrogen oxide, Nitrogen dioxide, etc. are global cooling gasses while Nitrous oxide (N2O) is a greenhouse gas.
- If greenhouse gases are not checked, by the turn of the century the temperature may rise by 5°C.
- According to scientists, this temperature increase will harm the environment and cause unusual climatic changes (like an increase in the frequency of El Nino), which will accelerate the melting of the polar ice caps as well as ice caps in other regions, such as the Himalayas.
Cryosphere: The cryosphere is the frozen water part of the Earth’s water system. Polar regions and snow caps of high mountain ranges are all part of the cryosphere.
How does this impact?
This will cause the sea level to rise over a long period, submerging many coastal areas and causing the loss of coastal habitats, including the most crucial ecosystems in terms of ecological services, such as marshes and swamps.
Gas V/S Sources and Causes
Carbon dioxide (CO2): Burning of fossil fuels, deforestation
Chlorofluorocarbons (CFCs): Refrigeration, solvents, insulation foams, aero propellants, industrial and commercial uses
Methane (CH4): Growing paddy, excreta of cattle and other livestock, termites, burning of fossil fuel, wood, landfills, wetlands, and fertilizer factories.
Nitrogen oxides (N2O): Burning of fossil fuels, and fertilizers; burning of wood and crop residue.
Carbon Monoxide (CO): Iron ore smelting, burning of fossil fuels, burning e-waste.
- In terms of meteorology, carbon dioxide is a very significant gas because it is transparent to solar radiation coming in but opaque to radiation leaving the earth.
- A portion of the radiation from the earth’s surface is reflected toward the surface after being partially absorbed by it. The greenhouse effect can be largely attributed to it.
- Its concentration is greater close to the earth’s surface as it is denser than air.
- Ozone is another important greenhouse gas. But it is in very small proportions at the surface.
- Most of it is confined to the stratosphere where it absorbs harmful UV radiation.
- Pollutants such as NO2 react with volatile organic compounds at ground level in the presence of sunlight to produce ozone (tropospheric ozone).
Why does water vapour consider a unique greenhouse gas?
Because it absorbs both incoming (part of incoming) and outgoing solar radiation.
It may account for four per cent of the air by volume in the warm and wet tropics, while it may account for less than one per cent of the air in the dry and cold desert and polar regions.
- Water vapour is also a variable gas in the atmosphere, which decreases with altitude.
- Water vapour also decreases from the equator towards the poles.
- Methane is the most important greenhouse gas after carbon dioxide.
- It is produced from the decomposition of animal wastes and biological matter.
- The emission of this gas can be restricted by producing gobar gas from animal waste and biological matter (methane).
Nitrous Oxide (N2O)
- N2O or Nitrous Oxide is a greenhouse gas.
- NO and NO2 (nitric oxide or nitrogen oxide and nitrogen dioxide) emissions cause global cooling by forming (OH) radicals that destroy methane molecules, thereby offsetting the effect of GHGs.
- Carbon monoxide is a short-lived greenhouse gas (it is less dense than air).
- It has an indirect radiative forcing effect by increasing methane and tropospheric ozone concentrations via chemical reactions with other atmospheric constituents (e.g., the hydroxyl radical, OH.) that would otherwise destroy them.
- Through natural processes in the atmosphere, it is eventually oxidized to carbon dioxide.
- Because of their role in ozone depletion (explained in Geography > Climatology > Polar Vortex), CFCs were phased out through the Montreal Protocol.
- This anthropogenic compound is also a greenhouse gas, with a much greater capacity to amplify the greenhouse effect than CO2.
Know more about Montreal Protocol and the Kigali agreement click here:
- Hydrofluorocarbons are used as refrigerants, aerosol propellants, solvents, and fire retardants.
- These chemicals were developed as a replacement for chlorofluorocarbons (CFCs).
- Unfortunately, HFCs are potent greenhouse gases with long atmospheric lifetimes.
- Perfluorocarbons are compounds that are produced as a by-product of aluminum production and semiconductor manufacturing.
- Like HFCs, PFCs generally have long atmospheric lifetimes and high global warming potential.
- Sulfur hexafluoride is also a greenhouse gas.
- It is used in the production of magnesium and semiconductors, as well as as a tracer gas for leak detection.
- Sulfur hexafluoride is used in electrical transmission equipment, including circuit breakers.
- Black carbon (BC) is a solid particle or aerosol (though not a gas) that contributes to global warming.
Is Black carbon and soot are same? Yes
Soot is another name for black carbon. Soot is a form of particulate air pollutant, produced from incomplete combustion.
When deposited on snow and ice, black carbon warms the earth by absorbing heat in the atmosphere and decreasing albedo (the ability to reflect sunlight).
Black carbon is the strongest absorber of sunlight and heats the air directly.
- Furthermore, it darkens snowpacks and glaciers through deposition and causes ice and snow to melt.
- Regionally, Black carbon disrupts cloudiness and monsoon rainfall.
- Black carbon stays in the atmosphere for only several days to weeks.
- As a result, the effects of Black carbon on atmospheric warming and glacier retreat vanish within months of reducing emissions.
- As a result, the effects of BC on atmospheric warming and glacier retreat vanish within months of reducing emissions.
- Biomass burning (possibly domestic wood burning) has been identified as a significant source of brown carbon.
- Brown carbon is commonly referred to as a greenhouse gas, while black carbon refers to particles produced by impure combustion, such as soot and dust.
- GHG Protocol is creating standards, tools, and online training to assist countries, cities, and businesses in tracking their progress toward their climate goals.
- The Greenhouse Gas Protocol (GHG Protocol) establishes frameworks for measuring and managing greenhouse gas (GHG) emissions from private and public sector operations, value chains, and mitigation actions.
- The GHG Protocol arose in the late 1990s when the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD) recognized the need for an international standard for corporate GHG accounting and reporting.
Global Warming – Impacts
Melting of the ice caps refers to?
Melting of the ice caps and glaciers will lead to a rise in sea level.
The thermal expansion also contributes to sea level rise.
Fertile coastal agricultural lands will be submerged, and saline water intrusions will degrade neighbouring land. Groundwater in such areas will be rendered ineffective.
- Populous cities lying on the coasts will be submerged under the sea.
- Flooding in the Himalayas and Ganga plains during the wet season, and drought during the dry season will have a devastating impact on the country.
- The amount of arable land in the high-latitude region is likely to increase as a result of the melting of snow and the reduction of frozen land.
- At the same time, arable land along the coastlines are bound to be reduced as a result of rising sea level and saline water inundations.
Extreme Climatic Events
- The increased likelihood of extreme events such as heat waves, flooding, hurricanes, and so on will cancel out all economic gains.
- Changes in rainfall patterns (E.g. 2015 Chennai floods, and the 2018 Kerala floods) will severely impact agriculture.
- Reduced hydroelectric power generation due to glacier abnormal behaviour will increase reliance on fossil fuels.
- The widespread extinction of animal populations due to habitat loss will add to the list of ‘threatened’ and ‘extinct’ species.
What are the Rising Health-Related Issues?
- The spread of diseases (like malaria, etc.) in the tropics will put more pressure on the healthcare sector.
- The increased frequency and severity of heat waves and other extreme weather events are expected to increase the number of deaths.
- Lack of freshwater during droughts and contamination of freshwater supplies during floods jeopardize hygiene, increasing the prevalence of diseases such as cholera and diarrhea.
How Biodiversity Loss occurred?
- The loss of plankton due to sea-level rise will harm the marine food chain.
- The bleaching of coral reefs (ocean rainforests) will result in a significant loss of marine biodiversity.
- Rising temperatures would necessitate more fertilizer for the same production targets, resulting in higher GHG emissions, ammonia volatilization, and crop production costs.
- Rising temperatures will have an even greater impact on the physical, chemical, and biological properties of freshwater lakes and rivers, threatening many individual freshwater species.
No Food Security
- Climate change affects crops by influencing irrigation, insolation, and pest prevalence.
- Drought, flood, storm, and cyclone frequency are likely to increase agricultural production variability.
- Crop yields in temperate regions are expected to benefit from moderate warming (an increase of 1 to 3°C in mean temperature), while crops in lower latitudes will suffer.
- However, natural disasters caused by global warming may outweigh the benefits in temperature regions.
- Sea level rise will exacerbate water resource constraints in coastal areas due to increased salinization of groundwater supplies.
Deterioration of Carbon sinks
- High-latitude forests store more carbon than tropical rainforests.
- One-third of the world’s soil-bound carbon is in taiga and tundra areas.
- Permafrost melts as a result of global warming, releasing carbon in the form of carbon dioxide and methane.
- The tundra was a carbon sink in the 1970s, but it is now a carbon source due to global warming. (Global warming causes even more global warming.)
Sea Level Change
- Sea level change means the fluctuations in the mean sea level over a considerably long period.
Processes that cause Change in Sea Level
- Eustatic changes happen when the amount of seawater changes as a result of things like
- global warming and melting of ice sheets (rise in sea level) or ice ages (fall in sea level) and
- changes in the volume of mid-oceanic ridges.
2. Tectonic changes occur due to a change in the level of the land.
- The addition or removal of load causes isostatic changes. During the ice ages, the weight of the glacial ice caused the landmass to sag. On the other hand, as the glacial ice is melted, landmasses rise.
- Epeirogenic movement is caused by the large-scale tilting of continents, which may cause one part of the continent to rise while the other part may sink, giving the appearance that the sea level is rising.
- Orogenic movement (mountain building) results in the formation of lofty mountains and an apparent fall in sea level.
Importance of understanding Sea Level Changes
It provides key evidence regarding climate change in the past. It helps in estimating the rates of tectonic upliftment in the past geological periods.
- to determine whether coastal areas are suitable for industrial and agricultural development.
- To protect low-lying countries by building coastal dykes and embankments.
- Only when we are aware of the areas that will likely be affected by future sea level rise can we map the areas that will likely experience storm surges and intermittent flooding.
- It becomes possible to build tidal power generation facilities in suitable locations by identifying the areas that may soon be submerged.
Changes in Global Sea Level
- Short-term changes occur during a year.
- Commonly, seasonal variations of 5-6 cm in sea level are observed in a year.
Short-term sea level change may be due to a complex interaction of the following factors:
- Marine water density: Seawater density depends on temperature and salinity. Seawater has a high density due to low temperature and high salinity, which results in a falling sea level.
- Atmospheric pressure: Low-pressure results in higher local sea levels and vice versa. E.g. Storm surge.
- The velocity of ocean currents: The edges of fast-moving ocean currents that follow curved paths experience an increase in sea level.
- Generally, a difference of 18 cm in sea level is observed between the two sides of a fast-flowing current.
- Ice formation and fall in sea level: Sea levels fall during the winter as a result of ocean water being trapped in the icecaps of the northern and southern hemispheres.
- Piling up of water along windward coasts: As a result of an air mass pushing water toward the coast, the sea level rises locally in coastal areas. For instance, during the monsoon season, sea levels rise in south and east Asia as a result of the air mass moving inland.
The twentieth century has observed short-term global sea level rise due to the following factors.
- Ocean water has expanded thermally in the past century as a result of anthropogenic global warming. In other words, in the last 100 years, the sea level has increased by 10 to 15 cm.
- To some extent, the melting of Antarctica’s ice sheets, which account for about 3% of the world’s total ice mass, has contributed to the rise in sea level.
- About 15% of the Greenland ice cap’s total volume melted during the 20th century.
- Other glaciers are estimated to have contributed about 48% of the rise in sea level globally, in addition to these ice-melt regions.
- Only if the major ice sheets melt or the volume of the world’s mid-oceanic ridge significantly changes are global sea level changes of more than 100 m possible.
Impact of Sea Level Fall
- Coral reefs perish when the sea level drops because the continental shelves where they are formed become dry. Therefore, along the edge of the dead corals, new coral reefs appear.
- The decrease in sea level causes more aridity in the continental hinterland where there are shallow continental shelves because there is less surface runoff.
- Ice caps and glacial tongues spread out onto the continental shelves as a result of a decline in sea levels in temperate and high-latitude regions.
Impact of Possible Rise in Sea Level
If the atmosphere’s temperature rises further, Antarctica’s ice melt could become hazardous soon.
Low-lying, densely populated coastal areas, which make up a significant portion of the populated land, will be submerged. Even the tiny islands will perish.
A rise in sea levels will have an impact on the estimated one billion people living on the planet.
- Immense damage may be caused to coastal structures like ports, industrial establishments, etc.
- Nearly 33% of the world’s croplands may be submerged due to the rise in sea level (coastal plains and deltas are made up of very fertile soils).
- Accelerated coastal erosion may cause damage to and destruction of beaches, coastal dunes, and bars.
- As a consequence, a vast section of the coastal land will remain unprotected against the direct attack of sea waves.
- Groundwater resources of the coastal regions will be severely affected by salinization due to marine water intrusion.
The destruction of the reefs, coral atolls, and deltas will cause significant harm to the ecosystem. On the periphery of the dead corals, new coral reefs will form.
The mouths of drainage basins will be submerged due to the rise in sea level. The long profiles of the rivers will need to be readjusted as a result, and they probably show a rise.
- The recent rise in sea level has had the greatest impact on islands. The Carteret Islands, which are in the Pacific Ocean northeast of Papua New Guinea, and the Tuvalu Islands, which are in the South Pacific about 1000 km north of Fiji, are two of the islands that are impacted.
The United Nations Environment Programme (UNEP) established the “Oceans and Coastal Areas Programme Activity Centre” in 1987 to investigate the phenomenon of sea level rise and to determine which nations are most at risk of submersion.
Reducing Carbon in the Atmosphere to fight Climate Change.
Half of the world’s electricity is generated by burning coal. Coal will remain a dominant energy source for years to come.
- CO2 and CO (carbon monoxide) are the major greenhouse gas that is released during the burning of coal.
- Along with the above gases, nitrogen oxides (destroys ozone) and sulphur oxides (acid rains) are also released.
- Clean coal technology seeks to reduce harsh environmental effects by using multiple technologies to clean coal and contain its emissions.
- Some clean coal technologies purify the coal before it burns.
One type of coal preparation, coal washing, removes unwanted minerals by mixing crushed coal with a liquid and allowing the impurities to separate and settle.
Other systems control the coal burn to minimize emissions of sulphur dioxide, nitrogen oxides, and particulates.
- Electrostatic precipitators remove particulates by charging particles with an electrical field and then capturing them on collection plates.
- Gasification avoids burning coal altogether. With gasification, steam and hot pressurized air or oxygen combine with coal in a reaction that forces carbon molecules apart.
- The resulting syngas, a mixture of carbon monoxide and hydrogen, is then cleaned and burned in a gas turbine to make electricity.
Wet scrubbers, or flue gas desulfurization systems, remove sulphur dioxide, a major cause of acid rain, by spraying flue gas with limestone and water.
Low-NOx (nitrogen oxides) burners reduce the creation of nitrogen oxides, a cause of ground-level ozone, by restricting oxygen and manipulating the combustion process.
Carbon capture and storage
‘Carbon capture and storage catches and sequesters (hides) carbon dioxide (CO2) from stationary sources like power plants.
Capture: Flue-gas separation removes CO2 and condenses it into a concentrated CO2 stream.
After capture, secure containers sequester the collected CO2 to prevent or stall its re-entry into the atmosphere.
The two storage options are geologic and oceanic (must hide the CO2 until peak emissions subside hundreds of years from now).
Due to this rise in atmospheric carbon, much emphasis has been placed on and hope placed on soil, plants, and trees’ capacity to temporarily store the carbon that burning fossil fuels releases into the atmosphere.
The Kyoto Protocol, the primary tool used by the international community to stop global warming, suggests that reducing carbon dioxide emissions from fossil fuels while also allowing trees and soil to absorb carbon dioxide is a valid strategy.
Article Written by: Remya