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Greenhouse Gases & Terrestrial Life : Humans
Transcript of Greenhouse Gases & Terrestrial Life : Humans
Some examples of greenhouse gases include water vapour (H2O), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O).
The abnormal increase of ‘greenhouse gases’ due to human activities cause more than just normal heat to be trapped in the atmosphere
At this point, the process is now called global warming
Human Influences: The Chemistry
Greenhouse gases absorb infrared (long-wave, heat) radiation. This is the form of the sun's energy reflected off the earth's surface. Greenhouse gases then radiate heat energy back toward the earth. This heats the earth's atmosphere and ultimately contributes to increasingly warmer climates, and this is known as global warming. Common greenhouse gases include carbon dioxide (CO2), chlorofluorocarbons (CFCs), methane (CH4), nitrous oxide (N2O), and tropospheric ozone (O3).
Human Influences : The Climate
Some greenhouse gases come from natural sources. Evaporation adds water vapor to the atmosphere. Animals and plants release carbon dioxide when they respire, or breathe. Methane is released naturally from some low-oxygen environments, such as swamps. Nitrous oxide is produced by certain processes in soil and water. Volcanoes—both on land and under the ocean—release greenhouse gases, so periods of high volcanic activity tend to be warmer. Scientists say that without the greenhouse effect, the average temperature of the Earth would drop from 14˚C (57˚F) to as low as –18˚C (–0.4˚F). Levels of several important greenhouse gaseshave increased by about 25 percent since large-scale industrialization began around 150 years ago During the past 20 years, about three-quarters of human-made carbon dioxide emissions were from burning fossil fuels. Concentrations of carbon dioxide in the atmosphere are naturally regulated by numerous processes collectively known as the “carbon cycle”
Human Influences: The Biology
All populations will be affected by climate change, but some are more vulnerable than others. Humans are impacted by climate change directly through changing weather patterns and indirectly through changes in water, air, food quality and quantity, ecosystems, agriculture, and economy.
Affects of Climate Change Include:
- Increase of Ozone levels and Particulate Matter
- Increase of UV Radiation
- Increase of Diseases
- Increased Heat Waves
- Disturbance in the Environment
Greenhouse Gases & Terrestrial Life : Humans
What are Greenhouse Gases?
Carbon dioxide (CO2)
is a byproduct of the combustion
As the practice of burning fossil fuels grows, so does the amount of carbon dioxide emitted to the atmosphere
During the process of combustion, O2 reacts with glucose (C6H12O6, a form of sugar) to produce water and CO2.
As the organic matter burns, chemical energy in the form of heat and light is released.
The following chemical equation describes the chemical process of combustion:
6 O2 + C6H12O6 --------> 6 H2O + 6 CO2 + energy.
production of methane - methanogenesis, can occur in a number of ways
occurs in freshwater wetlands, such as rice paddies.
land used for rice paddies grows = so does the amount of methane it produces
During the microbial metabolic process of methanogenesis, acetate (CH3COOH) is split into CO2 and CH4:
CH3COOH --------> CO2 + CH4.
Nitrous oxide (N2O)
is a byproduct of nitrification and denitrification--the natural processes by which NH4+ and NO3-, respectively, are biotically transformed
the use of nitrogen fertilizer on agricultural fields stimulates these processes and thus increases the production of N2O
Tropospheric ozone (O3
is a greenhouse gas that can be produced from another greenhouse gas--methane
This process involves many steps, the net reaction of which is described by the chemical equation:
CH4 + 4O2 --------> HCHO + H2O + 2O3
Another source of tropospheric ozone is atmospheric nitrate (NO2). First, the nitrate is broken down into nitric oxide (NO) and a single atom of oxygen (O):
NO2 + sunlight --------> NO + O;
Then, the atom of O combines with a molecule of O2 to produce O3:
O + O2 --------> O3
The net reaction, which is in equilibrium is:
NO2 + O2 <--------> NO + O3
Nitrogen dioxide (NO2)
NO2 Guideline Values
40 μg/m3 annual mean
200 μg/m3 1-hour mean
As an air pollutant, NO2 has several correlated activities.
At short-term concentrations exceeding 200 μg/m3, it is a toxic gas which causes significant inflammation of the airways
NO2 is the main source of nitrate aerosols, which form an important fraction of PM2.5 and, in the presence of ultraviolet light, of ozone.
The major sources of anthropogenic emissions of NO2 are combustion processes
Sulfur dioxide (SO2)
20 μg/m3 24-hour mean
500 μg/m3 10-minute mean
SO2 is a colourless gas with a sharp odour. It is produced from the burning of fossil fuels and the smelting of mineral ores that contain sulfur
The main anthropogenic source of SO2 is the burning of sulfur-containing fossil fuels
Health effects are now known to be associated with much lower levels of SO2 than previously believed.
•A greater degree of protection is needed.
Although the causality of the effects of low concentrations of SO2 is still uncertain, reducing SO2 concentrations is likely to decrease exposure to co-pollutants.
Studies indicate that a proportion of people with asthma experience changes in pulmonary function and respiratory symptoms after periods of exposure to SO2 as short as 10 minutes.
The movement (“flux”) of carbon between the atmosphere and the land and oceans is dominated by natural processes. While these natural processes can absorb some of the net 6.1 billion metric tons of anthropogenic carbon dioxide emissions produced each year, an estimated 3.2 billion metric tons is added to the atmosphere annually. The Earth’s positive imbalance between emissions and absorption results in the continuing growth in greenhouse gases in the atmosphere.
Carbon Flux Cycle
Trends in Atmospheric Concentrations and Anthropogenic Emissions of Carbon Dioxide
How does Climate Change occur?
Three factors affect the degree to which any greenhouse gas will influence global warming:
its abundance in the atmosphere
how long it stays in the atmosphere
its global-warming potential
Carbon dioxide has a significant impact on global warming partly because of its abundance in the atmosphere, CO2 stays in the atmosphere for thousands of years.
methane is about 21 times more efficient at absorbing radiation than CO2, giving it a high GWP rating, even though it stays in the atmosphere only about 10 years.
Most of the gases that people put into the atmosphere comes from burning fossil fuels
Another way humans release gases into the atmosphere is by cutting down forests, because trees contain large amounts of carbon.
Increased Ozone and PM Levels
Ozone at ground level, one of the major constituents of photochemical smog. It is formed by the reaction with sunlight of pollutants such as nitrogen oxides (NOx) from vehicle and industry emissions and volatile organic compounds (VOCs) emitted by vehicles, solvents and industry. Global warming and depletion of the stratospheric ozone layer will have a direct effect on the production of ozone at the earth's surface a mix of very small drops of liquid with small particles.
Particulate Matter: a small discrete mass of solid or liquid matter that remains individually dispersed in gas or liquid emissions (usually considered to be an atmospheric pollutant). The major components of PM are sulfate, nitrates, ammonia, sodium chloride, carbon, mineral dust and water. It consists of a complex mixture of solid and liquid particles of organic and inorganic substances suspended in the air.
Affects of PM and Ozone
respiratory symptoms such as coughing, wheezing and difficulty breathing
aggravated asthma or other respiratory diseases
increased susceptibility to respiratory infection
accelerated aging of the lungs
diminished lung capacity
decreased lung function
aggravated asthma, bronchitis and emphysema
Ozone can irritate your respiratory system
Ozone may aggravate chronic lung diseases, such as emphysema and bronchitis
exposure to modest levels of ozone can cause nausea, chest pain and pulmonary congestion.
Exposure to ultraviolet radiation is caused by the use of chemicals such as chlorofluorocarbons that deplete the ozone layer and allow harmful amounts of ultraviolet radiation to reach earth’s surface. Depletion of stratospheric ozone leads to an increase in UV exposure and temperature which damages the genetic material of DNA, increasing the risk of skin cancer and cataracts.
burning of the skin in sun, change of colour is caused by an expansion of the skin's blood vessels.
A permanent tan will occur when the UV radiation causes a pigment called melanin to form in the pigment cells of the skin
Over a period of years, exposure to radiation originating from the Sun causes damage in the skin's connective tissues, so-called photo-aging. This shows itself as a thickening of the skin, as wrinkles and decreasing elasticity
: increases in non-melanoma skin cancer and malignant melanoma skin cancer; increases in eye diseases, primarily cataract; and possible alterations in the immune response
Diseases Spread By Insects
Climate change may increase the risk of some infectious diseases, particularly those diseases that appear in warm areas and are spread by insects,
Malaria is a parasitic disease borne by mosquitoes which on reaching the bloodstream causes blood cells to rupture, causing a fever, chills and anemia in the victim and potentially resulting in death within hours.
Aedes mosquito vector of dengue is also highly sensitive to climate conditions. Dengue fever is transmitted by mosquitoes and causes fevers, joint and muscle pain, and headaches
Viral encephalitis is another disease carried by the mosquito and the tick and which results in an inflammation of the brain that can result in a brain hemorrhaging
Leishmaniasis is another parasitic disease carried by the sand fly which can infect the human body, namely the lymph nodes, the spleen and the bone marrow and which attacks the immune system and can result in death due to complications that arise.
Cholera is a parasitic disease which can cause death from dehydration as it causes excessive diarrhea
Greenhouse gases causing global warming can soon become a risk factor for heat strokes, cardiovascular and respiratory problems. Heat waves—another consequence of global warming—can lead to thousands of heat-related deaths.
cause heat cramps as a result of dehydration which can lead to organ failure and death
Pollen and other aeroallergen levels are also higher
can trigger asthma
decreases in crop yields
dry conditions ripe for wildfires
Increasingly variable rainfall patterns are likely to affect the supply of fresh water, Floods are also increasing in frequency and intensity.
drought and famine
heighten the risk of water-borne diseases
Increased exposure to toxic chemicals
Potential trend for more severe hurricanes as they are fueled by warm ocean waters
glaciers and ice caps melt faster than usual, causing sea levels to rise (70 meters)
displacing millions of people
By: Sara Asghar, Piali Bhati, Rifth Marfud, Earl Vidad