All the planets in the Solar System, Earth is extraterrestrial, the only 'living planet' on which there is life. Our existence is based on the earth and we are dependent on it. It is our imperative to save it. In fact, the earth is not just a land surface, but is mainly a unified form of four circles. These circles are- lithosphere, hydrosphere, biosphere and atmosphere. Each divisional part has an invisible effect on our life system. To understand the atmosphere in the Earth's atmosphere, one has to understand the whole system of interdisciplinary information and their interactions. These circles affect our climate and environmental environment in different ways.
The atmosphere is divided into several layers on the basis of heat, whose details are as follows:-
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
5. Exosphere
All these atmospheric layers are stacked on top of each other and are separated on the basis of altitude and temperature. Figure-9.1 shows how the temperature of different layers varies with altitude. Similarly, the figures of pressure decrease according to the height. For example, the pressure at an altitude of 50 km is much less than the pressure at the surface of the earth.
The part of the atmosphere that is closest to and near the Earth's surface is the 'troposphere'. This part contains all the elements of climate like clouds, rain and snow etc. In this part the temperature decreases upwards, with a rate of 6.5°C. per km of happens. In this part the temperature changes every day as well. 75% of the 'air' present in the atmosphere resides in this circle. Simultaneously, the pressure also decreases with altitude. Therefore, the speed and properties of air in this circle keep on changing according to the surface of the earth. The height of this circle is relatively low at the Earth's poles, while it is highest (17–18 km) around the equator.
The surface above this circle is called the stratosphere, in which the most 'ozone' is found. The temperature in this surface varies with altitude, which is why this part absorbs the ultraviolet (UV) radiation of the Sun. It is because of this process that this divisional part becomes important for us. Although some chemical gases such as chlorofluorocarbons, freons and halons, which have been used in refrigeration in the past, continue to affect this part of the atmosphere. Now their use is almost out. The air in this area is dry and relatively low, so it helps jet aircraft to escape.
The surface above the stratosphere which is about 35-40 km. It is called the 'mesosphere' where the temperature decreases with altitude and the minimum is -90 ° C. level is reached. It is the coldest part of the atmosphere.
The 'thermosphere' and the 'ionosphere' as a part of it lie above the mesosphere. Again there is an excess of temperature in this zone, which increases with the height. The reason for this high temperature is that this part of the atmosphere absorbs the Sun's energetic ultraviolet (UV) and X-rays. Whereas the ionosphere reflects and absorbs radio waves, which is what we use to receive shortwave radio transmissions. The uppermost part of the atmosphere is called the 'exosphere' which is about 500 km. is at the height of. It mainly contains molecules of oxygen, hydrogen helium, but only very few of them are present.
The major gases present in the atmosphere are carbon-dioxide, nitrous oxide, methane, etc., very important in maintaining proper warming of the atmosphere. Due to the expected excess in the level of all these gases, there is an unexpected increase in the temperature of the earth's surface, as a result there is also a proportional increase in the average temperature of the world. Roughly 78% nitrogen, 21% oxygen, 0.93% argon, 0.04% carbon-di-oxide and a very small percentage of neon, helium, methane, krypton and hydrogen are found in the atmosphere. For complete information about 'green house gases (GHG)' in the atmosphere, it is necessary that their solubility in water, carbon-di-oxide (Co2) embodied in plants, Co2 level in soil and rocks. Like limestone, coal, gas, oil, methane hydrate, which release a large amount of greenhouse gases into the atmosphere. Prominent causes of rising levels of greenhouse gases are industrialization, increasing vehicular pollution, continued reduction in tree and vegetation cover, and glacial retreat.
Earth's climate system consists of air, water, snow, land and vegetation, and the change in these components over time is what defines 'climate change'. The main factors are the processes of change within the Earth, changes in the Earth's own orbit and the power of the Sun, etc. can be some possible factors. Undoubtedly, honorable activities are also one of the main causes of climate change. Some of these changes are rapid, affecting the atmosphere or land, ocean surfaces, sea ice and vegetation, while others, such as mountain glaciers, oceanic ice giants, and changes produced by tectonic processes are slow, even over centuries.
(B). Climate change in the geo-time table
Climate is an integrated form of the average temperature, rainfall or snowfall of an area. Earth's climate is dependent on air, earth and water, which have changed over time. The fundamental factors of these changes are (i) the tectonic process, (ii) the motion of the earth and the influence of the sun and (iii) human influence. Some of these changes affect rapidly, while some change the climate gradually, but their effect is clearly on the marine environment, the surface of the earth, the snow-covered area and the vegetation. Changes that affect the global climate system at a very slow rate include glaciers, deep ocean systems, coastal areas, and topography.
This type of climate change system is not new according to Earth's schedule. Climate changes have been occurring throughout the geological history of the Earth (Figure 9.2) and this action is inevitable. Such changes happen very slowly. For example, in the Holocene epoch (4800-6300 years ago), the Thar Desert was a wetland with wetlands or lakes, due to winter rainfall and strong monsoon rainfall at that time. Similarly present-day Kashmir, which was once a warm subtropical climate, shifted to a cooler temperate climate (2.6 - 3.7 million years ago). Gradually these winters or extended winter years kept coming. As for the Earth's climate, it would also be surprising that the Indian subcontinent remained close to the Australian continent about 40–50 million years ago, south of the equator. About 6000 km of the continent The displacement journey of ie, before and after hitting the European plate, went through an era of many types of changes, in which climate change is also one.
About 542 million years ago in the history of the Earth's time table, Earth's climate change can be divided into "greenhouses" or "ice-houses". In Fig. 9.2 this type of classification is shown according to the Bhusaari. It is known from this that the 'Ice Age' occurred many times in the geological history of the Earth.
There were 5 main events of climate change in the land table, due to which the animals were completely destroyed. In the Jurassic period (69 years ago), large creatures such as dinosaurs died out. Figure 9.3 shows the four main 'Ice Ages', while also indicating the Holocene climate optimum with an interval of several ice and warm ages in the Holocene epoch (about 10,000 years ago).
(C) Climate System Change
Continuous monitoring of climate parameters showed that sea level rose by 0.1 to 0.2 m during the 20th century. Rainfall in the Northern Hemisphere increased global mean temperatures between 0.4 and 0.8 °C over the past decade, with the detection of salinity anomalies in the North Atlantic Ocean (IPCC 2001). The accelerating rate of the past warming trend may be higher than the available estimate.
The human impact on the climate system is clear and the recent emissions of greenhouses and their past history have had a massive impact on recent climate change, particularly on human and natural systems. The warming of the climate system is evident. Since the 1950s, many years of unpredictable climate change have been unprecedented compared to previous centuries. The atmosphere and oceans have warmed, the amount of ice has decreased, and the sea level has also risen. Relevant Special Report by the Working Group of the Government Panel on Climate Change (IPCC), which provides a holistic view of climate change (Fig. 9.4a, b) and the Fifth Assessment Report (AR. - 5), the main points are as follows-
- After each of the last three decades, there has been a continuous increase in the warming of the Earth's surface compared to any preceding decade. The period from 1983 to 2012 was the warmest in the Northern Hemisphere in the last 1400 years.
- Globally, land and ocean surface temperatures are 0.85 °C calculated from a linear trend (period 1880 to 2012)
- The increase in energy stored in the climate system between 1971-2010 was found to be high in the oceans (about 90 per cent) while it was only 1 per cent in the atmosphere.
- On average, there has been an increase in rainfall after 1 cyclonic cyclone over the mid-latitudes of the Northern Hemisphere.
- Changes in ocean surface salinity provide indirect evidence of changes in the global water cycle.
- Since the Industrial Revolution, an increase in the amount of Co2 in the oceans has led to acidification while alkalinity has decreased.
- In the period from 1992 to 2011, the ice sheets of Greenland and Antarctica have been losing their volume on a large scale. There has been a decrease in the size of glaciers around the world. Ice surface areas have decreased since the 1980s due to increased surface temperatures.
- Arctic seas receded at a rate of 3.5 to 4.1 percent per decade from 1979 to 2012. The sharpest decrease occurred in the summer. The extent of sea ice increased by 1.2 to 1.8 percent from 1979 to 2012. Although in Antarctica, sea ice has decreased in some areas and increased in some areas.
- The global mean sea level has risen by 0.19 meters in the period from 2001 to 2010. The rate of sea level rise since the 19th century has been higher than the average rate during the past two centuries. The warming of the climate system is therefore evident and unprecedented changes have been recorded for many years, especially since the 1950s. The oceans and atmosphere are warming, the amount of ice and snow has decreased, and sea levels are rising.
Climate change is now affecting every continent and almost every country in one way or another. Even the effects of these changes are adversely affecting the economies of some countries and the world community is beginning to feel its cost. Weather patterns are changing, sea levels are rising and weather events are becoming more extreme. Greenhouse gas emissions are now at an all-time high. The average temperature of the Earth's surface by the end of this century will be 3°C. likely to exceed. Due to which poor and weak people will be affected more. At present, practicable measures are available to reduce these adverse effects, which can deal with this global problem to a great extent. The most important is to use innovative sources of energy that minimize carbon emissions.
Climate change is a global choice that does not respect national boundaries. This is an issue that needs a solution that encourages developing countries to help them move towards a low carbon economy.
In order to strengthen the global response to the levels of climate change, 175 countries of the world have implemented a resolution to adopt the "Paris Agreement-2016" from November 2016. According to this agreement, the global temperature will be reduced by 2 ° C. All countries agree to bring the level to or below. 175 countries have ratified the agreement and 10 developing countries have also submitted the first iterative reports of their national adaptation plans to respond to climate change. Global warming to 1.5°C. This would lead to far-reaching and unprecedented and positive changes in all aspects of society. This will help in ensuring a just society.
