International cooperation on climate change problem

Frame convention on climate change (FCCC, Rio de Janeiro, 1992): the main aim is to stabilize greenhouse gas emissions at a level, which would prevent dangerous anthropogenic interference with the climate system. Industrial nations decided to return to 1990 emissions by 2000. Unfortunately, few countries have actually reduced greenhouse gas emissions.

Total annual amount of CO₂ emissions is 22 mln tons. The range of 5 countries with highest industrial output of CO₂: USA (produces 1/5 of CO₂), China, Canada, Russia, Japan.

 

Kyoto Protocol (Japan, 1997): collectively, more than 160 industrial countries agreed on new treaty and decided to roll back greenhouse gases about 5% below 1990 levels by 2012. Kazakhstan ratified Kyoto protocol on 26 February 2009.

Carbon tax – a tax leveled on fossils (or any fuels) in proportion to the amount of carbon emitted during combustion (introduced by competent international, national or local organizations).

Carbon credit – unrealized amount of permitted carbon emissions; credits in terms of unrealized carbon emissions (in international calculations through the CO₂ restriction policy to mitigate global climate change).

Car Emissions: CO₂ is the main Greenhouse Gas. Gasoline used in our cars as fuel when burning produces CO₂ that contributes to Greenhouse Effect.

Car emission coefficient shows how much emissions are released into the atmosphere by unit volume of gasoline. It is measured in: kg/L, kg/gallon, the emissions may be expressed in kg of carbon (C) or kg of carbon dioxide (CO₂).

For regular type of gasoline car emission coefficient equals to 2.5 kg of C /gallon. To calculate CO₂ equivalent, use CO₂ / C conversion factor: 3.67.

Fuel consumption rate (or simply gas mileage) shows fuel consumption by a car and may be expressed in: km/L or L/100 km.

Examples: 10 km/L means that 1 liter of gasoline is required to drive 10 km.

7 L/100 km means that 7L of gasoline allow to drive 100 km.

Fuel efficiency of a car is estimated by fuel consumption rate: the lower consumption rate, the more ‘fuel efficient’ is this car.

Ethanol Blends of fuel: Ethanol produced by fermenting corn and other crops reduces GHG and air pollutants’ emissions.

E10 or ‘gasohol’ contains 10% ethanol and 90% gasoline. Сheaper than gasoline, can be used in any vehicle types. E85: 85% ethanol + 15% gasoline. Used only in special Flex-Fuel Vehicles. Ethanol has lower energy content (heating value), resulting in higher fuel consumption.

Biodiesel – commercially available diesel replacement fuel manufactured from vegetable oils or animal fats. Produces less GHGs than regular diesel.

Electricity contribution to GHG effect: Electric power plants use coal to produce energy. Burning coal releases CO₂ into the atmosphere thereby increasing GHG effect. CO₂ Emission Coefficient for Electricity = 0.75 kg CO₂/kWh shows mass of CO₂ in kg released into the atmosphere per kilowatt-hour (kWh).

Lecture 10

Topic: Stratosphere Ozone Depletion. Acid Rains.

Section objectives:

1. The nature of ozone and mechanism of ozone layer work

2. Ozone depletion: history, sources and the effects of ozone layer destruction

3. Air pollution: wet and dry smog, indoor air pollution.

4. The nature, sources & the effects of acid rain

5. Sustainable strategies on ozone depletion & acid rain problems. International cooperation

1. The nature of ozone and mechanism of ozone layer work

troposphere ~ 8-15 km

stratosphere ~ 50-60 km

mesosphere ~ 95-120 km

thermosphere ~ 600 km

Ozone gas (O₃) - is a form of oxygen, which is present in the atmosphere.

Ozone exists at two levels. At ground level, it is poisonous to life (Tropospheric ozone). In the stratosphere, it exists as a layer 15 to 55 km above the earth, where it forms an important barrier against harmful ultra-violet (UV) rays from the sun (Stratospheric ozone).

The ozone layer is a renewable form of protection that converts harmful UV radiation into heat. UV includes: UV-A (320 – 400 nm); UV-B (280 – 320 nm; UV-C (220 – 280 nm). Ozone layer filters out all the sun’s ultraviolet in the range of 220 nm – 290 nmOzone also helps to control the temperature of the outer stratosphere.

How to measure Ozone? The atmospheric ozone columnar density above a point on the earth's surface is measured in Dobson units (DU) One Dobson unit refers to a layer of ozone that would be 10 µm thick under standard temperature and pressure. For example, 300 DU of ozone brought down to the surface of the Earth at 0 °C would occupy a layer only 3 mm thick. One DU is 2.69×10²⁰ ozone molecules per square meter.

A baseline value of 220 DU is chosen as the starting point for an ozone hole since total ozone values of less than 220 Dobson Units were not found in the historic observations over Antarctica prior to 1979. The Dobson unit is named after Gordon Dobson, who in the 1920s built the first instrument to measure total ozone from the ground.

2. Ozone depletion: history, sources & the effects of ozone layer destruction

In the upper atmosphere ozone is regularly created and destroyed naturally. The activity of the sun causes variations in the Ozone layer throughout the year.

The Chapman Reactions

O2 + hv	®	O + O	(1)
O + O2	®	O3	(2)
O3 + hv	®	O2 + O	(3)
O + O3	®	O2 + O2	(4)

Reaction (2) becomes slower with increasing altitude while reaction (3) becomes faster. The concentration of ozone is a balance between these competing reactions. In the upper atmosphere, atomic oxygen dominates where UV levels are high. Moving down through the stratosphere, the air gets denser, UV absorption increases and ozone levels peak at roughly 20km. As we move closer to the ground, UV levels decrease and ozone levels decrease. The layer of ozone formed in the stratosphere by these reactions is sometimes called the 'Chapman layer'.

However, certain artificial chemical gases also destroy ozone. Although these gases are harmless to humans, they drift up to the stratosphere, where they form the compounds that destroy ozone.

CFCs (Chlorofluorocarbons) are most important of these gases, in term of quantity and impact. There is no natural way to remove them once they are in the atmosphere. Not only do they contribute to ozone destruction, but they are also one of the main greenhouse gases (See the topic: "Greenhouse effect").

History: Scientists have been measuring the concentration of ozone over the Antarctic since 1957. They have noticed it thinning significantl)- in the last 10 to 15. years. Dramatic loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970s by a research group from the British Antarctic Survey (BAS) who were monitoring the atmosphere above Antarctica from a research station.

In 1982 they discovered an unexpectedly large fall in concentration, and an expedition in 1987 found an ozone "hole" the size of the USA and deeper than the height of Mount Everest. A similar hole has now been detected in the Arctic. In 1991 it was found that ozone was being destroyed tuice as fast as had been expected.

Loss of ozone has serious environmental effects. Sunlight supplies the energy for life on earth, but it also contains UV radiation (especially UV-B), which causes living tissue to decompose. Ozone absorbs UV light, so destruction of the ozone layer allows much more radiation from the sun to reach the earth's surface than normal.

Two primary threats on ozone layer:

- release of CFC

- jet travel in the stratosphere (nitric oxide, NO)

Industries can contribute to ozone depletion if:

They manufacture chemicals that damage ozone: CFCs and HCFCs, methyl chloroform, carbon tetrachloride or halons.

They use CFCs or HCFCs:

- in freezers, air conditioners and cooling systems. These chemicals are released only after these products have been disposed of.

- as solvents to clean and degrease products such as electronic circuit boards.

- as propellants in aerosol cans such as spray-on glue.

- to make synthetic foam and packaging.

They use methyl chloroform for metal cleaning, in adhesives or for electronic cleaning.

They use carbon tetrachloride in any chemical process.

They use fire extinguishers that contain halons.