GREEN HOUSE EFFECT

The greenhouse effect is the process of absorption and emission of infrared radiation by the gases in the atmosphere which tends to warm earth’s atmosphere and surface. It was first investigated by Svante Arrhenius in 1896 and was firstly proposed by Joseph Fourier in 1824.

Human activity since the industrial revolution has increased the amount of green house gases in the atmosphere. It was recorded that the concentration of CO₂ and methane have increased by 36% and 148% respectively since 1750. These are the highest level that are ever recorded during the last 65000 years. Three quarters of the increase in the amount of carbon dioxide is produced by fossil fuel burning while the rest is due to deforestation.

Human activities are being continued on the earth. Therefore, carbon dioxide emissions are also continuing to rise due to continue human activities like burning of fossil fuel and deforestation.Emission scenarios have been made to estimate the changes in emission level of green house gases in the future. The future level of emissions will depend on uncertain economic, sociological, technological, and natural developments.

In most scenarios, it is found that emissions continue to increase over the century while in some these emissions are reduced. These emission scenarios combined with carbon cycle have been used to predict how the concentration of greenhouse gases will change in the future.

Using the six IPCC SRES "marker" scenarios, models suggest that by the year 2100, the atmospheric concentration of CO₂ could range between 541 and 970 ppm.^[46] This is an increase of 90-250% above the concentration in the year 1750.

How the green house effect occurs

To understand green house effect, first we need to know how the temperature is regulated on earth. The earth absorbs heat energy that comes to the earth from the sun. Generally, these are the rays having shorter wavelength. To maintain a steady temperature on the earth, the earth too reflects or radiates the energy back to the atmosphere. During this process, shorter wavelength rays that came to earth returns back with longer wavelength. There are some of the gases in the atmosphere like carbon dioxide, methane which do not allow the longer wavelength rays to pass through them. They act as blankets over the surface and help in warming up the earth.
Therefore, global temperature is maintained on the earth with nearly 30ºC warm, providing a suitable condition for the survival of human beings. This is named as green house effect as the glass in a green house also possesses the similar features to the atmosphere. It has been really advantageous in the agricultural field because using this method, non- seasoned crops can be grown at any time and the crops will not need to be specified to a certain area.
Even the beneficial thing can sometimes have a negative impact. Similarly, due to the rapid increase of the green house gases, it has proven to be threatening as the temperature of earth is being rapidly increased and human beings and other living organisms are being more prone to the effect of climate change.
Human activities such as burning of fossils fuels (coal, oil and gas) and emission of gases from the vehicles have increases the amount of carbon dioxide and methane in the atmosphere. These gases lead to increased global warming.


It is of great concern that we are more likely to experience change in terms of extreme weather such as floods, droughts and storms due to natural variability in climate. It is thought that these hazards will be more intense with the global warming.

CLIMATE VARIABILITY IN PAST AND ITS EFFECTS

If we look at the past evidences, it is found out that over the past century a lot of climate variability or the climate change has occurred due to volcanic eruptions, fluctuation in the solar energy, and other natural variations. Then, since 1970s there is rampant increase in the green house gases because of human activities. The record shows that 1990 has been warm in terms of global average temperature. 1998 was the warmest year and more specifically; first eight months of 1998 were the warmest of those months on the record.

If human does not control the activities that may lead to global warming and the concentration of carbon dioxide increases by twice its value, then most probably, the temperature of the earth increases by 2.5 ºC. It may seem to be less, but it is actually the annual increase in temperature of earth. This 2.5ºC rise represents about half an ‘ice-age’ in terms of climate change and it is obviously the rapid change.
If we look at the past evidences, it is found out that over the past century a lot of climate variability or the climate change has occurred due to volcanic eruptions, fluctuation in the solar energy, and other natural variations. Then, since 1970s there is rampant increase in the green house gases because of human activities. The record shows that 1990 has been warm in terms of global average temperature. 1998 was the warmest year and more specifically; first eight months of 1998 were the warmest of those months on the record.

If human does not control the activities that may lead to global warming and the concentration of carbon dioxide increases by twice its value, then most probably, the temperature of the earth increases by 2.5 ºC. It may seem to be less, but it is actually the annual increase in temperature of earth. This 2.5ºC rise represents about half an ‘ice-age’ in terms of climate change and it is obviously the rapid change.

GREEN HOUSE GASES

Green house gases are carbon dioxide, methane, chlorofluoro carbons. Naturally occurring green house gases have a warming effect of about 33 °C. Water vapour, which is one of the green house gases causes about 36-70 percent of green house effect, methane causes 4-9 percent green house effect and ozone causes 3-7 percent of green house effect. Clouds are also responsible for the green house effect.

Role of greenhouse effect on global warming

Green house effect is obviously an important phenomena in human life as it has made the life on the earth possible. Without it, the earth won’t be warm enough for human survival. However, due to the excessive release of the green house gases, the earth is heating up so fast that green house gases that were once thought of as essential have been fearful enough to cause global warming on the earth. During this era, it has been the most debated issue. The earth is rapidly drowning into the great ocean of global warming. It has threatened whole life on earth. Droughts, hurricanes, floods, changes in sea level and islands and inhabitants disappearing have been common nowadays and these are all due to global warming.

How the global warming occurs and its effects

GLOBAL WARMING

Climate change is the fluctuation in the climate condition that may range for a long period of time from decades to millions of years. It may be limited to a small area or may even cover the whole earth. It is generally referred to as Global Warming.

HUMAN CAUSES
• Human uses fossils fuels excessively to generate power. Excessive use of the fossils fuel results in the rapid emission of green house gases. Carbon dioxide is one of the major gas that is emitted and is responsible for the global warming.
• Besides this, there are CFC gases that come out from house equipments like refrigerator and ACs and these gases too help in increasing the temperature of earth.
• Human emits carbon dioxide through different ways. Nevertheless, there are seas which absorb these gases. But the problem is that these oceans absorb green house gases very slowly. So, there is great probability of rapid increase of global warming.
• Deforestation in large scale has lower the number of trees to absorb carbon dioxide for photosynthesis and this is also one of the human cause of global warming.
• Cultivation of paddy in the fields also adds methane in the atmosphere.
• The release of nitrous oxide from agriculture and manufacturing activities traps three hundred times more heat than carbon dioxide. it has been recorded that the level of nitrous oxide has been rapidly increased since the pre industrial era.

NATURAL CAUSES OF GLOBAL WARMING
Human causes are not the sole cause of increasing issue of global warming. Many natural causes have been found out to be responsible for global warming by the scientists. They include:
• Continental drift and mountain formation
• Changes in the orbit of the earth
• Volcanic eruption
• Solar variability
• Fluctuation in solar energy.

EFFECT OF GLOBAL WARMING ON NEPAL

The major effect of it in Nepal is poor crop yield. Nepal; is an agricultural nation where most of the people depends on yielding of crops for their survival. Due to the global warming and the extreme temperature, people out her hae to face water shortages, and poor crop yield.Farmers say that changing climate patter has greatly affected the crop yielding leaving them unable to feed themselves and getting into debt.

Nepal is observing an unpredictable climate pattern. Sometimes there is an intense rainfall while in other times there is drought. There are drier winters and delayed monsoons. These changes have great impact on the melting of the Himalayan glaciers. This effect could be seen beyond Nepal as well.

Not only the environment is affected by the climate change, but also humans are affected and this effect has been more concentrated on the women. Climate change has resulted into drought in most of the places and has forced women to travel farther to fetch water and also they need to take responsibility to feed their family since the male members migrate seasonally in search of jobs.

Nepal is one of the world’s poorest nations, with 31% of its 28 million-population living below the poverty line. It has one of the lowest emissions records in the world – just 0.025% of total global greenhouse gas emissions.

CONSEQUENCES OF GLOBAL WARMING

Greenhouse gases can retain in the atmosphere for a long period of time ranging from decades to million of years. Human preventing measures can't even mitigate its effect on the earth. Therefore, its effects can be prevailed on earth and that may harm whole of the human civilization.

1. Melting of polar ice caps
The most ongoing issue that is taking place globally is melting of the ice caps. It is a four pronged danger.
• Rise in sea level all over the world. It is estimated that if all the glaciers that exist today melt, then there will be increase in the sea level by 230 feet.
• Imbalance in the global ecosystem. The melting ice caps are fresh water and when they mix with the ocean water, desalinization of water takes place. It shuts down or increases the irregularity in the smooth functioning of ecosystem.
• Extinction of weaker species of animals. As evidenced by Darwin, only the fittest and the most adaptable species of animals will survive in the environment of increasing temperature and changing landscapes. Therefore, there is an extinction of those species which can’t adapt to the changing environment of the earth.
• The melting of ice caps allows much more heat to enter this atmosphere. Since ice caps are white in colour, they reflect most of the sunlight back to atmosphere. There are only seas to reflect and absorb the sunlight in absence of seas. Therefore, most of the sunlight enters into the earths atmosphere and is trapped, hereby rising the temperature of the earth.

2. Economic consequences
Global warming has an obvious effect on the human and environment. In addition to these, it has an equal effect on the economic sector of countries of the world. Money is spent to treat and control the diseases, billions of dollars is destroyed during hurricanes and again a lot of money is required to renovate all these. So, it is also a cause for increasing recession of the world.

3. Increase in probability of droughts and heat waves

Global warming may wet some areas of the earth. Nevertheless, other areas may have increased probability and intensity of droughts and heat waves. The most affected region due to this is the country Africa which has born the adverse effects and these have exacerbated its condition.

4. Warmer waters and more hurricanes
Global warming is accompanied by increase in the temperature and this results in more possibility of hurricanes as in 2004 and 2005.

5. Spread of diseases
As the temperature of the earth increases, the earth plunges into the threatening situation of global warming. As the northern hemisphere gets warmed up, disease carrying insects migrate to the north bringing diseases with them like plague and malaria. Sometimes, these diseases become epidemic and may place the whole human civilization in danger.

FOSSILS FUELS AS THE CAUSE OF CLIMATE CHANGE

For the first time in human history, people are the most responsible for the changing earth temperature. The dramatic increase in the use of fossils fuels (coal, oil and natural gas) by the human result in the increment of greenhouse gases into the atmosphere and these gases cause the climate change.

The major sources of green house gases are factories which provides us with electricity, vehicles that help us for the movement and agriculture that are the primary source of food.

Positive impacts of global warming

First, look at the positive facet of global warming bfore analyzing its negative consequences.
1. It has proven to be beneficial to the crops. Crops need carbon dioxide for photosynthesis. When there is increase in the amount of carbondioxide, it aids for the growth of crops.
2. At high northern latitude where there is longer winter period, winter will be less cold.
3. By using the technique of green house effect, we should not wait for the appropriate season to grow certain crops. Instead, every season will be equally appropriate for most of the crops. We can grow summer crops in the winter as well.
4. This technique has been beneficial to grow the desert plant in any areas of the wrl by maintaining the temperature and other conditions.

Negative impacts of green house effect

1. First, there is expansion of ocean water and increase in the ocean level due to the melting of ice caps.
2. Warming up of water means a higher rate of evaporation which results in greater amount of water vapor content in the atmosphere. Because the latent heat of condensation is the main energy source for the atmosphere’s circulation this leads to a more vigorous hydrological cycle.
3. In some areas, there may be heavy rainfall while in others there may be no rainfall. So, there is possibility of frequent and intense flood and droughts too.

Floods and droughts are the most devastating natural agents that may lead to death, misery and economic damage. It could be more devastating than any other impacts.

Action to mitigate climate change

Today, the issue of global warming has been a concern for all the nations of the world. Therefore, certain steps should be taken to reduce its effects. First of all, the emission of green house gases by the human activities must be reduced. For these, many technologies have been introduced which uses renewable resources like production of energy from the solar power, biomass, wind or water which can be used in various industries and these are independent of fossils fuels. This greatly reduces the emission of green house gases and also it facilitates the next generation with the required non renewable resources.
Next, removal of carbon dioxide from the atmosphere to some extent can also help in the mitigation of global warming of the climate change. This can be done with the help of plants and that means afforestation in the barren areas can help to stop the rapid climate change in the earth.
Third is that, we should reduce the emissions of the methane gases by the leakage from mines and landfill sites. The government and other wold agencies must play a vital role in educating the people about the impacts of the unnecessary and excessive use of the non renewable resources as well as encouraging them to use the alternative ways or clean technologies that will help to save the environment