CLIMATE CHANGE & MITIGATION STRATEGIES

• Climate – condition of temperature, humidity, pressure, wind, rainfall, and other meteorological elements on the Earth’s surface for a long ti
• Climate change is an old phenomenon. But currently considered as alteration in climatic conditions due to anthropogenic processes resulting in change of the global atmosphere.

 

GLOBAL WARMING

• Global warming– “Global warming is a gradual increase in the earth’s temperature generally due to the greenhouse effect caused by increased levels of carbon dioxide, CFCs, and other pollutants.
• Reasons: Greenhouse gases released + Fossil fuels combustion + Deforestation + Agriculture & livestock.

GREEN-HOUSE EFFECT

• A naturally occurring phenomenon that blankets earth’s lower atmosphere and warms it, maintaining temperature suitable for living things to survive.
• They balance cooling and warming of the earth.
• In the absence of this, earth surface temperature would be -19 degrees Celsius instead of current 15 degrees Celsius.
• Human-induced greenhouse gas emissions upset the natural balance & lead to increased warmth.

 

GAS	NATURAL SOURCE	HUMAN-INDUCED SOURCE	REMOVAL	GLOBAL WARMING POTENTIAL	ATM. LIFETIME (YRS)
WATER VAPOUR Biggest contributor	Evaporation from oceans etc.   Amount of vapour in air related to amount of other greenhouse gases present	Humans not directly responsible   CO2 and other GHGs present increase water vapour in air	—	—	—
CARBON DIOXIDE (CO2) Primary GHG	Ocean exchange, Animal/human respiration, Soil respiration, Volcanic eruptions and Wildfires	Combustion of fossil fuels, Industrial emissions, Chemical & mineral reactions	Reduce fossil fuel usage   Carbon sequestration	1	50 – 200
METHANE (CH4)	Wetlands, (largest) Oceans, Volcanic eruptions and Wildfires	Agriculture, Industries, Landfills, Waste water	Reduce waste	21	10-15
NITROUS OXIDE (N2O)	Earth’s nitrogen cycle   Bacteria breaking it down in soils and oceans	Agriculture, Transportation, Fossil fuel, combustion During production of nitric acid	Absorbed by certain bacteria   Destroyed by UV rays or chemical reactions	310	120
FLUORINATED GASES: 1)Hydrofluorocarbons-HFCs. 2)Perfluorocarbons-PFCs 3)Sulphur Hexafluoride – SF6	—	Aluminium & semi-conductor manufacturing Refrigerants, Aerosol, propellants, Fire retardants, Magnesium processing, Circuit breakers	Destroyed by sunlight in far upper atmosphere	● HFC – 150 to 11,700 ● PFC – 6,500 to 9,200 ● SF6 – 23,900	● HFC – 1.5 to 209 ● PFC – 2,600 to 50,000 ● SF6 – 3,200

 

GREEN HOUSE GASES (GHG)

• Natural as well as anthropogenic gaseous constituents of the atmosphere which absorb and re-emit infrared radiations.
• 2 important characteristics of GHGs are:

1. How well the gas absorbs energy
2. How long the gas stays in the atmosphere.

• Global Warming Potential (GWP) for gases is the total energy that the gas absorbs for a certain period of time, mostly 100 years. GWP always compared to CO2 as its GWP is ‘1’ and is baseline.
• CFCs, HFCs, HCFCs and SF6 are called high-GWP gases because they trap more heat that CO2.

 

• BLACK CARBON: Incomplete combustion of fossil fuels + Inorganic + Contains soot (jet black colour) + Cause respiratory disorders + Absorbs visible sunlight + Found in vehicular emissions.

 

• BROWN CARBON: Combustion of biomass + Organic + Brown colour + Causes respiratory diseases + Absorbs Ultraviolet part of sun’s rays + Ground level ozone, found in smog.

 

Radiative Forcings	Change in earth’s energy balance due to alterations in climate Positive forcing – increases temperature Negative forcing – reduces temperature
Natural Forcings	Changes in amount of energy emitted by sun. Very slow variations in earth orbit Slight increase in solar energy since industrial revolution
Human-Induced Forcings	Due to greenhouse gases and aerosol emissions from fossil fuels Modification of land surface due to deforestation, agricultural use, etc.
Human-Generated Greenhouse Gases	Have warming effect, i.e. Positive climate forcing Largest climate forcing agent is co2 emitted from combustion of fossil fuels
Human-Generated Aerosols	Burning fossil fuels adds aerosols to atmosphere Aerosols include water, ice, mineral dust, ash or acidic droplets Aerosols have cooling effect Aerosols deflect sun’s energy & affect formation & life of clouds

 

CLIMATE FORCING

• Climate forcing is the physical process of affecting the climate on the Earth through a number of forcing factors.
• Positive forcing: GHGs warm the earth
• Negative forcing: Aerosols & volcanic eruptions cool the earth.

 

TYPES:

• Natural forcing – do not harm climate or cause drastic global temperature variations.
• Human-made forcing – GHGs, aerosols, etc.

 

RECEDING GLACIERS – A SYMPTOM OF GLOBAL CLIMATE CHANGE

• Arctic Pole – Black line indicates spread of ice-sheet in the 20th century. It is evident that the glaciers have been receding ever since and melted ice is the result of the rising ocean levels.
• Scientists predict that by 2030, more glaciers will have melted resulting in potential threat to aquatic as well as terrestrial ecosystems.
• Include impact on agriculture, reduced food security, health, pests and disease burden increase such as dengue, Malaria, atmospheric circulation (cyclones in Arabian sea), monsoon patterns, changing ecosystems (forest fires etc), impact on oceans, economic losses etc.

 

Climate change Temperature fluctuations Impact on water supply Droughts/ Agricultural losses Loss of biodiveristy

 

CARBON SEQUESTRATION

Carbon sequestration is a process to capture and store CO2 to curb global warming. It is captured from the air, industries or power stations and stored permanently underground. This promotes:

• Long-term reserve of CO2 or forms of carbon to control temperatures.
• Lowering of amount of GHGs present in air due to combustion of fossil fuels.

 

3 main steps to Carbon Capture and Storage (CCS)

Trapping & separating CO₂ from other gases à Transporting captured CO₂ to storage location à Storing CO₂ far from atmosphere, either in deep ocean or underground.

 

Types of CO2 Sequestration

 

Ocean sequestration	● Through direct injection or fertilization
Geological sequestration	● Natural pore spaces in geological foundation ● Has largest potential
Terrestrial sequestration	● Stored in soils and vegetation through decomposed matter & photosynthesis respectively.

 

Geological sequestration trapping mechanism

 

Hydrodynamic trapping	● Trapped as gas under low-permeability cap rock ● Combines with solubility trapping
Solubility Trapping	● Dissolved in oil, water, etc. ● Combines with hydrodynamic trapping
Mineral carbonation	● Forms stable compounds like iron, calcium by reacting with minerals/organic matter

 

Sinks

• Carbon sequestration is carried out by pumping carbon into ‘carbon sinks’
• This is an age-old process. Only recently, these sinks are also being used for capturing carbon for environmental reasons.
• NATURAL SINKS: Oceans, forests, soil, mangroves etc.
• ARTIFICIAL SINKS: Depleted oil reserves, un-mineable mines etc.

 

Carbon sinks (Green and Blue)

 

GREEN CARBON	BLUE CARBON
Removed by photosynthesis	Removed by tidal marshes, mangroves, seagrass
Stored in plants & soil	Stored in marine organisms, plants & sediments
Forests accumulate large amounts of carbon	Coastal ecosystems accumulate large amounts of carbon, 5 times more than forests
Afforestation and reforestation can enhance it	Found in all continents except Antarctica

 

The Blue Carbon Initiative

• Conservation International (CI), International Union for Conservation of Nature (IUCN) and the Intergovernmental Oceanic Commission (IOC) of UNESCO has collaborated with governments and organisations across the world to develop mechanisms for ensuring coastal Blue Carbon ecosystems.
• It also comprises:
• Engagement of local, national and international organisations
• Comprehensive methods for carbon accounting
• Incentive mechanism
• Scientific research for climate mitigation

 

CARBON CREDIT

A Carbon Credit is a tradable permit that certifies the right to emit 1 ton of CO2 or its equivalent.

 

How does this help?

As per gas emissions norms laid down by signatories of the Kyoto Protocol under UNFCCC, companies have two ways to reduce emissions:

• Reduce GHGs by adopting new technologies.
• Connect with developing countries to set up eco-friendly technology to earn credits. This credit becomes permit for company to emit GHGs in its own country.’

 

Status of developing nations

• India and China are biggest sellers. Europe biggest buyer.
• China is leading with 73% of market share, whereas India is second at 6%.
• India’s Multi Commodity Exchange (MCX) has become 1st exchange in Asia to trade carbon credits.

 

CARBON OFFSETTING

• Credits for reductions in greenhouse gases made at another location.
• Sold in metric tonnes of carbon dioxide equivalent.
• Fastest way to achieve deepest reductions in business dealings.
• Provide employment opportunities, community development programmes, training, education.
• Must meet essential quality criteria.
• Cannot be double-counted.

 

 

 

GLOBAL CARBON EMISSIONS IN VARIOUS SECTORS

 

SECTOR	% OF EMISSIONS
Agriculture & land use	24
Power	25
Buildings	6
Industry	21
Transport	14
Other	10

 

2.5 CARBON TAX

A carbon tax – levied on carbon content of fuels, generally in transport and energy sector.

Carbon taxes intend to:

• Reduce CO2 by increasing price of fossil fuels.
• Decreasing the demand of CO2
• Promote a form of carbon pricing

 

GEO – ENGINEERING

Geo-engineering is a technology that strives to modify, improve and cool the earth’s environment. The concept is still in its nascent stage.

 

Ideas under this technique and how it works

 

Copy a volcano	By infusing atmosphere with sulphur-dioxide gas through volcanic eruption, scientist believe it will block solar radiation and cool the planet Sulphur doesn’t heat stratosphere and has cooling effect
Shoot mirrors into space	To deflect sunlight and bring earth’s temperature back to pre-industrial levels Mirrors (size of Greenland) to be positioned between the planet and the sun
Seed the sea with iron	Phytoplankton prefer iron Iron pulls carbon out of atmosphere during photosynthesis Scientists believe stimulating phytoplankton growth will reduce global warming potential
Whiten clouds with wind-powered ships	Cloud tops reflect solar radiation Spraying sea-water into the sky through wind-powered ships will whiten clouds thus increasing reflection of solar radiation.
Build fake trees	‘Artificial tree’ is capable of capturing 1 ton of carbon in atmosphere per day Panels of absorbent resin on tree surface react with CO2 to form a solid Can compare this to a furnace filter.