Anthropogenic climate change

definition of anthropogenic climate change

Increased emissions of greenhoues gas( caron dioxide, methane, nitrous oxide) caused by human activities eg burning of fossil fuels, clearing of forests, food choices

carbon sink definition + examples

• any system that absorbs more carbon than it releases into the atmosphere through the carbon cycle

• carbon can be stored as organic materials in organisms, soil, fossil fuels, oceans

• eg atmosphere, ocean, soil, forests

carbon source + examples

• any system that releases more cabron than it stores

• eg mining and burning of coal

what factors affect the degree to which any GHG will influence global warming?

1. concentration or abundance in the atmosphere:

larger emissions lead to higher concentrations in the atmosphere, more global warming

2. atmospheric lifetime

time the GHG remains in the atmosphere, longer time, more global warming

3. global warming potential (GWP)

measure of the total energy that a gas absorbs over a particular period of time compared to carbon dioxide. higher GWP, more energy absorbed, more warming caused

natural processes that release carbon dioxide

• respiration in animals and plants

• soil respiration

• forest fires

• volcanic eruptions

Main human activities that emit CO2

1. Increase in energy usage

2. Deforestation for land-use change

How does increase in energy use result in CO2 emissions?

• energy is needed to transport people and goods as well for industrial processes

• electricity is generated through combustion of fossil fuels

• besides producing energy, industrial processes like production of cement also produce CO2

How does deforestation for land-use change contribute to CO2 emissions?

• Forests are important carbon sinks

• Clearing of forests for agricultural activities releases carbon stored in the trees into the atmosphere

• organic material in exposed soil also oxidises and decays to produce even more CO2 and CH4

Natural process that release methane

• decay of organic matter in oxygen-free conditions

• ruminant animals sucha s cattle

Main human activities that emit methane

1. Agriculture

2. Industrial activities

3. Waste landfill sources

How does agriculture contribute to methane emissions?

• Ruminant digestion in which domestic livestock(buffalo, cattle, sheep and goats) produce large amounts of methane their digestive process, enteric fermentation

• Manure management of livestock: Animals’ manure is stored or managed in lagoons or holding tanks where methane will be produced

• Rice paddies: warm waterlogged soil of rice paddies provide ideal conditions for bacteria to decompose organic matter and produce methane

How do the industrial processes contribute to methane emissions?

• methane is released during extraction, production, storage, transportation and combustion of fossil fuels such as oil, coal and natural gas

• they are also emitted when there is leakage in natural gas pipelines

How does landfill waste form residential, commercial and industrial activities contribute to methan emissions?

• methane is generated in landfills as waste decomposes in the absence of oxygen

Carbon footprint definition

• Total set of greenhouse gas emissions directly and indirectly caused by an individual, organisation or single event, service or product

• calculated over a set period (usually a year)

Carbon footprint of electricity generation technologies

• coal: highest carbon footprint. CO2 mostly generated from operation(combustion)

• nuclear power and renewable energy sources: significantly lower carbon footprint, primarily emitting GHGs during construction/manufacturing

• biofules: carbon-neutral. plants used to make biofuel help absorb CO2 and offset emission from the production or combustion biofules. However they have significant life-cycle GHG emissions form harvesting , processing and transport

Carbon footprint of food production

1. emissions from livestock production

• forests are cleared to grow feed crops and provide the large quantities of harvested feed required for livestock

• ranching-induced deforestation to provide land for cattle to graze

• Ruminant digestion (enteric fermentation)

• manure management (animal waste releases CH4 and N2O)

2. Emissions from meat processing: freezing and packaging require electricity and pump huge quantities of wastewater(source of GHGs)

3. Transportation (fossil fuel combustion)

4. Food waste: decomposition of food waste in landfill produces methane

Why does -based food production has lower carbon footprint?

require less land and water