Project Comenius 2009:Project Comenius 2009:

Together Against Climate Change 2009Together Against Climate Change 2009

The primary goal of this project is to present the ozone depleting substances and greenhouse gases that threaten the atmosphere

and influence the climate change.

1. Atmosphere

2. Greenhouse effect

3. Climate Change

4. Carbon Dioxide

5. Water vapour

6. Methane

7. Nitrogen Oxide

8. Chlorofluorocarbons

The gaseous envelope surrounding the Earth. The dry atmosphere consists almost entirely of nitrogen (78.1% volume mixing ratio) and oxygen (20.9% volume mixing ratio), together with a number of trace gases, such as argon (0.93% volume mixing ratio), helium, radioactively active greenhouse gases such as carbon dioxide (0.035% volume mixing ratio), and ozone. In addition the atmosphere contains water vapour, whose amount is highly variable but typically 1% volume mixing ratio. The atmosphere also contains clouds and aerosols

Vertical division into:

Carbon dioxide (and water) have absorptions near 7 and 15 microns that produce a greenhouse effect that warms the earth to a comfortable temperature for life as we know it. This picture shows how it works. Sunlight is either absorbed or reflected by the surface of the earth. The absorbed part heats the surface, and causes it to emit where the 15 micron greenhouse effect operates. Thus, some portion of the energy is trapped and warms the surface above the temperature for a planet without an atmosphere.From UCAR Communications,  http://www.ucar.edu/communications/newsreleases/2001/learnweb.html

The atmosphere keeps the Earth warmer by about 33 ºC without it the temperature would be about –18 ºC, in reality it is about 15 ºC.

glacier Rhônegletscher, Switzerland

Climate change refers to any significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer). Climate change may result from:

natural factors, such as changes in the sun's intensity or slow changes in the Earth's orbit around the sun; natural processes within the climate system (e.g. changes in ocean circulation);

human activities that change the atmosphere's composition (e.g. through burning fossil fuels) and the land surface(e.g. deforestation, reforestation, urbanization, desertification, etc.)

Any gas that absorbs infrared radiation in the atmosphere. Greenhouse gases include, but are not limited to, water vapour, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), chlorofluorocarbons (CFCs), hydro chlorofluorocarbons (HCFCs), ozone (O3 ), hydro fluorocarbons (HFCs), per fluorocarbons (PFCs), and sulphur hexafluoride (SF6). The following focus is on first five.

Methane

Carbon dioxide is one of the most abundant gasses in the atmosphere. Carbon dioxide plays an important part in vital plant and animal process, such as photosynthesis and respiration. A naturally occurring gas, and also a by-product of burning fossil fuels and biomass, as well as land-use changes and other industrial processes. It is the principal anthropogenic greenhouse gas that affects the Earth's radiative balance. It is the reference gas against which other greenhouse gases are measured and therefore has a significant Global Warming Potential.It is the gas without smell, with weakly sour taste, heavier than air, therefore it cumulates in lower layers of spaces and rooms and its average content is 0.034%. The concentration of carbon dioxide in the atmosphere has increased more in the northern hemisphere where more fossil fuel burning occurs. Since the Industrial Revolution the concentration globally has increased by 30%.The futureThe best case scenario for the increase in carbon dioxide emissions predicts that the concentration of carbon dioxide in the atmosphere will reach double the level of before the Industrial Revolution, in 2100. The worst case scenario brings this forward to 2045.

Carbon is the building block for all living things. The conversion of carbon dioxide into living matter and then back is the main pathway of the carbon cycle. Plants draw about one quarter of the carbon dioxide out of the atmosphere and photosynthesize it into carbohydrates. Some of the carbohydrate is consumed by plant respiration and the rest is used to build plant tissue and growth. Animals consume the carbohydrates and return carbon dioxide to the atmosphere during respiration. Carbohydrates are oxidized and returned to the atmosphere by soil microorganisms decomposing dead animal and plant remains (soil respiration).

There is actually very little of the total carbon cycling through the Earth system at any one point in time. Most of the carbon is stored in geologic deposits - carbonate rocks, petroleum, and coal - formed from the burial and compaction of dead organic matter on sea bottoms. The carbon in these deposits is normally released by rock weathering.

Figure ES.15 The Carbon CycleCourtesy NASA

Source: http://earthobservatory.nasa.gov/Library/CarbonCycle/carbon_cycle4.html

Another quarter of atmospheric carbon dioxide is absorbed by the world’s oceans through direct air-water exchange. Surface water near the poles is cool and more soluble for carbon dioxide. The cool water sinks and couples to the ocean's thermohaline circulation which transports dense surface water toward the ocean's interior. Marine organisms form tissue containing reduced carbon, and some also form carbonate shells from carbon extracted from the air.

The most abundant greenhouse gas, it is the water present in the atmosphere in gaseous form. Water vapor is an important part of the natural greenhouse effect. While humans are not significantly increasing its concentration, it contributes to the enhanced greenhouse effect because the warming influence of greenhouse gases leads to a positive water vapor feedback. In addition to its role as a natural greenhouse gas, water vapor plays an important role in regulating the temperature of the planet because clouds form when excess water vapor in the atmosphere condenses to form ice and water droplets and precipitation.

A hydrocarbon that is a greenhouse gas with a global warming potential most recently estimated at 23 times that of carbon dioxide (CO2). Methane is produced through anaerobic (without oxygen) decomposition of waste in landfills, animal digestion, decomposition of animal wastes, production and distribution of natural gas and petroleum, coal production, and incomplete fossil fuel combustion. (CH4) is a greenhouse gas that remains in the atmosphere for approximately 9-15 years. Methane is over 20 times more effective in trapping heat in the atmosphere than carbon dioxide (CO2) over a 100-year period and is emitted from a variety of natural and human-influenced sources. Human-influenced sources include landfills, natural gas and petroleum systems, agricultural activities, coal mining, stationary and mobile combustion, wastewater treatment, and certain industrial process. The futureThe rise in methane started more recently than the rise in carbon dioxide, and the process of removal from the atmosphere is difficult to predict. However, without technological change further increases in concentrations are inevitable.

A powerful greenhouse gas with a global warming potential of 296 times that of carbon dioxide (CO2). Major sources of nitrous oxide include soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning. Nitrous oxide emission levels from a source can vary significantly from one country or region to another, depending on many factors such as industrial and agricultural production characteristics, combustion technologies, waste management practices, and climate. For example, heavy utilization of synthetic nitrogen fertilizers in crop production typically results in significantly more N2O emissions from agricultural soils than that occurring from less intensive, low-tillage techniques. Also, the presence or absence of control devices on combustion sources, such as catalytic converters on automobiles, can have a significant affect on the level of N2O emissions from these types of sources.

The futureSince the Industrial Revolution, the level of nitrous

oxide in the atmosphere has increased by 16%.Due to the long time it spends in the atmosphere, the

nitrous oxide that we release today will still be trapping heat well into the next century.

Chlorofluorocarbons or CFCs (also known as Freon) are non-toxic, non-flammable and non-carcinogenic. They contain fluorine atoms, carbon atoms and chlorine atoms. The 5 main CFCs include CFC-11 (trichlorofluoromethane - CFCl3), CFC-12 (dichloro-difluoromethane - CF2Cl2), CFC-113 (trichloro-trifluoroethane - C2F3Cl3), CFC-114 (dichloro-tetrfluoroethane - C2F4Cl2), and CFC-115 (chloropentafluoroethane - C2F5Cl).CFCs are widely used as coolants in refrigeration and air conditioners, as solvents in cleaners, particularly for electronic circuit boards, as a blowing agents in the production of foam (for example fire extinguishers), and as propellants in aerosols. Indeed, much of the modern lifestyle of the second half of the 20th century had been made possible by the use of CFCs.

Man-made CFCs however, are the main cause of stratospheric ozone depletion. CFCs have a lifetime in the atmosphere of about 20 to 100 years, and consequently one free chlorine atom from a CFC molecule can do a lot of damage, destroying ozone molecules for a long time. Although emissions of CFCs around the developed world have largely ceased due to international control agreements, the damage to the stratospheric ozone layer will continue well into the 21st century.

Greenhouse gases emissions reached the highest level at the end of the 1980s. In the period of 1990-1994 there was a reduction by approximately 28%, and since the year 1995 the GHGs emissions have been at approximately the same level. Total green gases emissions (expressed CO2 equivalents) in 2004 reached 51 046.16 Gg excluding the sinks from the sector of Landscape Use - Changes to landscape use and forestry (LULUCF), which represents a reduction by almost 30% (22 000 Gg). Emissions, also known in literature as the net emissions including the sinks in the LULUCF sector reached 46 795.27 Gg in 2004. Total emissions excluding LULUCF dropped by 50 Gg, compared to 2003. This reduction represents approximately 1%. Methane (CH4) emissions in 2004 reached the level of 203.90 Gg, which is 7% less than the 2003 figures, and 33% less than the reference year of 1990. Total N2O emissions in 2004 reached 13.15 Gg, which is a slight increase compared to 2003; however, less by 33% than the reference year of 1990. N2O emissions show a slightly rising tendency since 2000, reaching highest values in the reference time period. Overall, we can say that greenhouse gases emissions show a decreasing tendency, with the exception of several years, mainly as a consequence of reduction in industrial fertilisers and volume of livestock.

At the conference of signatories to the UN Framework Convention on Climate Change in Kyoto, Japan, in December 1997, Slovakia bound itself to reduce the

production of greenhouse gases by 8% by 2008, compared to 1990. Today we can say that Slovakia has a real potential to meet the above mentioned objectives.

www.epa.govhttp://www.ucar.edu/communications/newsreleases/2001/learnweb.htmlhttp://www.umich.edu/~gs265/society/greenhouse.htmwww.enviroportal.skhttp://www.bbc.co.uk/climate/evidence/.shtmlhttp://www.greenpeace.org/raw/content/slovakia/press/reports/v-stava-klimaticke-zmeny.pdfhttp://www.ekoskola.sk/vzduch_atmosfera.htmhttp://www.sappo.sk