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Summary
Environment Class 14

BRIEF OVERVIEW OF PREVIOUS CLASS (1:09 PM)

CLIMATE CHANGE AND GLOBAL WARMING (1:13 PM)

  • Climate:
  • The climate refers to the atmospheric conditions of a place for a long period measured by a minimum of 30 years.
  • UNFCCC defines climate change as a change of climate attributed directly or indirectly to human activities that alter the composition of the global atmosphere and which is in addition to natural climate variability observed over a comparable period. 

CAUSES OF CLIMATE CHANGE (1:23 PM)

  • Milankovitch cycles result in changes in insolation, seasonal variations, etc. 
  • Volcanic eruption 
  • Thermodynamic circulation 
  • Continental drift 
  • Anthropogenic Factor:
  • Deforestation 
  • Change in land use pattern
  • Urbanization
  • Agriculture and Animal Husbandry
  • Energy intensive activity 
  • Radiative forcing:
  • The changes that have a cooling effect are called negative forcing. For example, an increase in Aerosol concentration causes a higher reflection of sunlight and cooling of the surface. 
  • A variety of physical and chemical changes which can affect the global energy balance and force changes in the earth's climate are called radiative forcing.

GLOBAL WARMING (2:10 PM)

  • Green Houses Gases: 
  • The major GHGs arranged in increasing order as per the global warming potential: C02
  • Global Warming Potential: 
  • GWP
  • Global Warming Potential is the measure of how much energy the emission from one tonne of gas is observed over a given period relative to the emission of 1 tonne of CO2. 
  • CO2:
  • Sources: fossil fuel, agriculture, industries (thermal, cement, etc), deforestation, etc 
  • Note: For the keeling curve kindly refer to the PPTs shown by the faculty.
  • Methane:
  • Sources: Wetland, ruminant emissions, biomass burning, termite emissions, landfills, geological sources, wild animals, etc. 
  • Nitrous oxides:
  • Sources: Agricultural soil management, wastewater treatment, stationary combustion, chemical production, transportation, and manure management etc.
  • Note: Kindly refer to the PPTs shown by the faculty for a better understanding of fluorinated gas.

EVIDENCE OF CLIMATE CHANGE (2:58 PM)

  • 1. Global rise in the temperature: AR6 of IPCC has observed that the average temperature of the earth has increased by 1.09°C since the late 19th century, out of which 1.07°C is due to human factors.
  • 2. Ocean warming: The top 100 m of oceans have shown warming of more than 0.33°C since 1969.
  • 3. The hottest year on record is 2023. Every decade has been the warmest compared to its previous. 
  • 4. Global sea level rise of 20 cm on average in the last century. 
  • 5. Melting of snow cover: The Arctic sea Ice has decreased by 40% in summers and 10% in March. It is expected that within 15 years there will not be any ice left in the Arctic region during the summers 
  • 6. Retreat of glaciers in almost every mountain i.e. Himalayas, Alps, Rockies and Andes, etc. 
  • 7. Ocean acidification: Since the beginning of the Industrial Revolution the acidity of the oceanic surface has increased by 30%.

IMPACT OF CLIMATE CHANGE (3:15 PM)

  • Increased melting of glaciers will impact the flow of river water. 
  • More glacial lakes are formed which may result in GLOF.
  • It reduces the availability of water in the long run, creating water stress. 
  • Impact water supply to agriculture 
  • Crops may become more water-intensive 
  • Increase rate of evaporation and disturbance in the condensation process due to an increase in air temperature. 
  • Intensity and frequency of rainfall changes. 
  • Increases the occurrences of drought due to irregular rainfall. 

OCEAN WARMING (3:20 PM)

  • Ocean warming causes more heating of the sea surface and disturbs various atmospheric phenomena such as the formation of cyclones, and the occurrence of El Nino, La-Lina and Indian Ocean dipole. 
  • The warming results in the formation of more stable and stratified upper layers.
  • It leads to less mixing of deeper and colder nutrient-rich water with the surface. 
  • The oxygen supply to the lower layer is limited creating oxygen-minimum zones. 
  • At higher temperatures, dissolved oxygen in the water decreases.
  • The high temperature of the water is harmful to marine species. For example: Coral bleaching. 
  • Higher temperature increases metabolic activities causing an increase in the oxygen demand. 

OCEAN ACIDIFICATION (3:30 PM)

  • Ocean acidification is increasing the acidity level of ocean water due to the observation of higher levels of CO2 is called ocean acidification.
  • It reduces the availability of carbonate ions in the water and increases the bicarbonate ions.
  • Note: For Impact kindly refer to the handout shared by the faculty. 

OZONE DEPLETION (3:44 PM)

  • Ozone is an allotrope of oxygen with three oxygen atoms. 
  • It is a pale blue gas with a pungent odour. 
  • It is mainly present in the stratosphere (90%) and helps in the filtration of UV rays. 
  • When UV rays pass through the ozone layer 100% of UV-A, 90% of UV-B and 5% of UV-C rays are absorbed. 
  • UV B - skin burning, Skin Cancer, etc. 
  • UV A - maximum tanning 
  • UV C - skin cancer, DNA damage, etc (most dangerous).
  • Ozone Oxygen cell:
  • O2 (Oxygen) + UV rays = O3 (Ozone)
  • O3 + Uv rays= O2 
  • Ozone-depleting substance (ODS):
  • Chlorine:
  • Substances: CFC, Carbon tetrachloride and Methyl Chloroform 
  • Sources: Refrigerant, propellants of aerosol, fire extinguisher, etc 
  • Bromine:
  • Substances: HBFC, Methyl Bromide
  • Sources: Fire extinguishers and pesticides 
  • Nitric Oxide:
  • Substances: Nitrous oxide
  • Sources: Industrial and agricultural use
  • Why they were used?
  • Most of these compounds were non-corrosive, non-inflammable, low toxic chemically stable, and long lifetime. 

THE TOPICS FOR THE NEXT CLASS: CONSERVATION