GLOBAL WARMING 1. The term "global warming" refers to the warming in recent decades and its projected continuation, and implies a human influence. Its the increase in the near-surface temperature of the Earth. 2. It is caused by the increase in the concentration of green house gases in the atmosphere of the Earth . 3. GLOBAL WARMING is now considered as one of the most critical problem on Earth.
GLOBAL WARMING HOW GLOBAL WARMING WORKS
Greenhouse Effect CAUSES
On Earth, the major greenhouse gases are water vapor carbon dioxide (CO2), methane (CH4), and ozone.
Greenhouse gases warm the atmosphere by efficiently absorbing thermal infrared radiation emitted by the Earth’s surface, by the atmosphere itself, and by clouds
As a result of its warmth, the atmosphere also radiates thermal infrared in all directions, including downward to the Earth’s surface
4. Thus, greenhouse gases trap heat within the surface-troposphere system GREENHOUSE EFFECT
CAUSES Solar Variation
Solar variations are changes in the amount of solar radiation emitted by the Sun.
It is estimated that the Sun may have contributed about 45–50 percent of the increase in the average global surface temperature over the period 1900–2000.
Solar variation combined with changes in volcanic activity probably did have a warming effect from pre-industrial times to 1950 .
Variations in solar output, may have contributed to recent warming .
CAUSES Land Use
Climate change is attributed to land use for two main reasons. While 66% of anthropogenic CO2 emissions over the last 250 years have resulted from burning fossil fuels, 33% have resulted from changes in land use, primarily deforestation
Deforestation both reduces the amount of carbon dioxide absorbed by deforested regions and releases greenhouse gases directly, together with aerosols, through biomass burning that frequently accompanies it
3. A second reason that climate change has been attributed to land use is that increase exposure of land to sunlight results in more absorption of heat leading to increases in temperatures.
IMPROPER LAND USE
Deforestation is the second principle cause of atmospheric carbon dioxide increase. It is responsible for 20-25% of all carbon emissions entering the atmosphere, by the burning and cutting of about 34 million acres of trees each year.
The destroying of tropical forests alone is throwing hundreds of millions of tons of carbon dioxide into the atmosphere each year.
The temperate forests of the world account for an absorption rate of 2 billion tons of carbon annually which are also lost.
In the temperate forests of Siberia alone, the earth is losing 10 million acres per year.
EFFECTS Extreme Weather
Hurricane modeling has produced the results, finding that hurricanes, simulated under warmer, high-CO2 conditions, are more intense .
However, hurricane frequency will be reduced.
Worldwide, the proportion of hurricanes reaching categories 4 or 5 – with wind speeds above 56 meters per second – has risen from 20% in the 1970s to 35% in the 1990s
EFFECTS Extreme Weather
As the climate grows warmer and the causes of global dimming are reduced, evaporation will increase due to warmer oceans
Because the world is a closed system this will cause heavier rainfall, with more erosion. This erosion, in turn, can in vulnerable tropical areas (especially in Africa) lead to desertification
On the other hand, in other areas, increased rainfall lead to growth of forests in dry desert areas.
Scientists have found evidence that increased evaporation could result in more extreme weather as global warming progresses
EFFECTS Glacier Retreat
Since 1980, glacier retreat has become increasingly rapid and ubiquitous, and has threatened the existence of many of the glaciers of the world
Excluding the ice caps and ice sheets of the Arctic and Antarctic, the total surface area of glaciers worldwide has decreased by 50% since the end of the 19th century.
The loss of glaciers not only directly causes landslides, flash floods and glacial lake overflow but also increases annual variation in water flows in rivers
EFFECTS Increase in Sea Level
With increasing average global temperature, the water in the oceans expands in volume, and additional water enters them which had previously been locked up on land in glaciers, for example, the Greenland and the Antarctic ice sheets.
For most glaciers worldwide, an average volume loss of 60% until 2050 is predicted.
The sea level has risen more and it may result in costal areas to get submerged into the sea
EFFECTS Acidification of Sea
The world’s oceans soak up much of the carbon dioxide produced by living organisms, either as dissolved gas, or in the skeletons of tiny marine creatures that fall to the bottom to become chalk or limestone
Oceans currently absorb about one tonne of CO2 per person per year. in water, carbon dioxide becomes a weak carbonic acid, and the increase in the greenhouse gas since the industrial revolution has already lowered the average pH (the laboratory measure of acidity) of seawater by 0.1 units, to 8.2
3. Predicted emissions could lower it by a further 0.5 by 2100, to a level probably not seen for hundreds of millennia and, critically, at a rate of change probably 100 times greater than at any time over this period
EFFECTS Conquences on Ecosystems
increasing global temperature means that ecosystems will change; some species are being forced out of their habitats (possibly to extinction) because of changing conditions, while others are flourishing
Secondary effects of global warming, such as lessened snow cover, rising sea levels, and weather changes, may influence not only human activities but also the ecosystem
The global temperatures predicted for the coming centuries may trigger a new ‘mass extinction event’, where over 50 per cent of animal and plant species would be wiped out.
EFFECTS Water Scarcity
Sea level rise is projected to increase salt-water intrusion into groundwater in some regions, affecting drinking water and agriculture in coastal zones .
Increased evaporation will reduce the effectiveness of reservoirs. Increased extreme weather means more water falls on hardened ground unable to absorb it, leading to flash floods instead of a replenishment of soil moisture or groundwater levels.
In some areas, shrinking glaciers threaten the water supply and continuation of the current retreat
EFFECTS Effect on Health
extreme high temperatures increase the number of people who die on a given day for many reasons: people with heart problems are vulnerable because one's cardiovascular system must work harder to keep the body cool during hot weather, heat exhaustion, and some respiratory problems increase
Global warming could mean more cardiovascular diseases, doctors warn. Higher air temperature also increases the concentration of ozone at ground level. In the lower atmosphere, ozone is a harmful pollutant. It damages lung tissues and causes problems for people with asthma and other lung diseases.
3. Global warming may extend the favorable zones for vectors conveying infectious disease such as dengue fever and malaria In poorer countries, this may simply lead to higher incidence of such diseases.
EFFECTS Methane Release from Melting Permafrost
Western Siberia is the world's largest peat bog, (a wetland type that accumulates acidic peat) a one million square kilometer region of permafrost peat bog that was formed 11,000 years ago at the end of the last ice age.
The melting of its permafrost is likely to lead to the release, over decades, of large quantities of methane. As much as 70,000 million tonnes of methane, an extremely effective greenhouse gas, might be released over the next few decades, creating an additional source of greenhouse gas emissions.
Similar melting has been observed in eastern Siberia
CONTROL Agriculture A significant effect of global climate change, especially global rainfall patterns may be upon agriculture. Extended drought can cause the failure of small and marginal farms with resultant economic, political and social disruption. A Drought tolerant crop varieties
Agriculture of any kind is strongly influenced by the availability of water. Climate change will modify rainfall, evaporation, runoff, and soil moisture storage.
Changes in total seasonal precipitation or in its pattern of variability are both important. The occurrence of moisture stress during flowering, pollination, and grain-filling is harmful to most crops and particularly so to corn, soybeans, and wheat.
Increased evaporation from the soil and accelerated transpiration in the plants themselves will cause moisture stress.
As a result, there will be a need to develop crop varieties with greater drought tolerance.
CONTROL Agriculture B More spending on irrigation
The demand for water for irrigation is projected to rise in a warmer climate, bringing increased competition between agriculture--already the largest consumer of water resources in semi-arid regions--and urban as well as industrial users.
Falling water tables and the resulting increase in the energy needed to pump water will make the practice of irrigation more expensive, particularly when with drier conditions more water will be required per acre.
CONTROL Weather Control
Russian and American scientists have in the past tried to control the weather, for example by seeding clouds with chemicals to try to produce rain when and where it is needed
A new method being developed involves replicating the urban heat island effect, where cities are slightly hotter than the countryside because they are darker and absorb more heat .
This creates 28% more rain 20-40 miles downwind from cities compared to upwind.
4. On the timescale of several decades, new weather control techniques may become feasible which would allow control of extreme weather such as hurricanes
CONTROL Energy Efficiency and Conservation
Energy which is saved by improvements in efficiency has, in practice, often provided good environmental benefit and provided a net cost saving to the energy user.
Energy conservation is the practice of increasing the efficiency of use of energy in order to achieve higher useful output for the same energy consumption.
Encouraging energy conservation among consumers is often advocated as a environmentally sensitive alternative to increased energy production
4. Non-conventional sources of energy like wind energy, solar energy etc.can be used
CONTROL Alternative Energy Sources A Nuclear Power
Nuclear power currently produces over 15% of the world's electricity.
Due to its extremely-low emittance of Greenhouse Gases and reliability it is widely seen as a possible alternative to fossil fuels, but is controversial for capital costs and possible environmental impacts.
CO2 emissions are estimated at 11 g/kWh for hydroelectric power, 950 g/kWh for installed coal, 900 g/kWh for oil and 600 g/kWh for natural gas generation but only 3.10 g/kWh for nuclear energy.
CONTROL Alternative Energy Sources B Renewable Energy
One means of reducing carbon emissions is the development of new technologies such as renewable energy such as wind power.
Most forms of renewable energy generate no appreciable amounts of greenhouse gases except for biofuels derived from biomass. Currently governments subsidize fossil fuels by an estimated $235 billion a year.
However, in some countries, government action has boosted the development of renewable energy technologies—for example, a program to put solar panels on the roofs of a million homes has made Japan a world leader in that technology, and Denmark's support for wind power ensured its former leadership of that sector.
CONTROL Alternative Energy Sources C Eliminating Waste Methane
Methane is a significantly more powerful greenhouse gas than carbon dioxide.
Burning one molecule of methane generates one molecule of carbon dioxide. Accordingly, burning methane which would otherwise be released into the atmosphere (such as at oil wells, landfills, coal mines, waste treatment plants, etc.) provides a net greenhouse gas emissions benefit.
However, reducing the amount of waste methane produced in the first place has an even greater beneficial impact, as might other approaches to productive use of otherwise-wasted methane
CONTROL Use the Fossil Fuels that Produce the Least Greenhouse Gases
Natural gas (predominantly methane) produces less greenhouses gases per energy unit gained than oil which in turn produces less than coal, principally because coal has a larger ratio of carbon to hydrogen
The combustion of natural gas emits almost 30 percent less carbon dioxide than oil, and just under 45 percent less carbon dioxide than coal. In addition, there are also other environmental benefits.
Thus the increased use of natural gas in the place of other, dirtier fossil fuels can serve to lessen the emission of greenhouse gases
CONTROL Carbon Capture and Storage
Carbon capture and storage (CCS) is a plan to mitigate climate change by capturing carbon dioxide (CO2) from large point sources such as power plants and subsequently storing it away safely instead of releasing it into the atmosphere.
Technology for capturing of CO2 is already commercially available for large CO2 emitters, such as power plants. Storage of the CO2 is envisaged either in deep geological formations, deep oceans, or in the form of mineral carbonates
CONTROL Seeding Oceans with Iron
Seeding the oceans with iron will increase phytoplankton populations, and thereby draw more carbon dioxide from the atmosphere.
A report in Nature, 10 October 1996, by K. H. Coale , measured the effects of seeding equatorial Pacific waters with iron, finding that 700 grams of CO2 were fixed by the resulting phytoplankton bloom per 1 gram of iron seeded.
However fertilizing the ocean is dangerous and lacks any guarantee of efficacy
CONTROL Kyoto Protocol
The primary international agreement on combating climate change is the Kyoto Protocol, which came into force on 16 February 2005.
The Kyoto Protocol is an amendment to the United Nations Framework Convention on Climate Change (UNFCCC).
Countries that have ratified this protocol have committed to reduce their emissions of carbon dioxide and five other greenhouse gases, or engage in emission trading if they maintain or increase emissions of these gases.
India and china are excluded from the Kyoto Protocol.
CONTROL Population Control
The population explosion is a fundamental factor that has led to global warming.
Because of this, various organizations promote population control as a means for mitigating global warming.
Proposed measures include improving access to family planning and reproductive health care and information, reducing natalistic politics, public education about the consequences of continued population growth, and improving access of women to education and economic opportunities.
The formation of the Himalayas resulted in blockage of frigid Central Asian air, preventing it from reaching India; this made its climate significantly warmer and more tropical in character than it would otherwise have been.
GREENHOUSE GASES EFFECTS OF GLOBAL WARMING ON INDIA 2. Ongoing sea level rises have submerged several low-lying islands in the Sundarbans, displacing thousands of people. Temperature rises on the Tibetan Plateau, which is causing Himalayan glaciers to retreat, may reduce the flow rate of the Ganges, Brahmaputra, Yamuna, and other major rivers; hundreds of thousands of farmers depend on these rivers. AWARENESS AMONGST PEOPLE 3. Tribal people in India's remote northeast plan to honour former U.S. Vice President Al Gore with an award for promoting awareness on climate change that they say will have a devastating impact on their homeland