Maharashtra Board Class 11 Geography Solution Chapter 5 – Global Climate Change
Balbharati Maharashtra Board Class 11 Geography Solution Chapter 5: Global Climate Change. Marathi or English Medium Students of Class 11 get here Global Climate Change full Exercise Solution.
Std |
Maharashtra Class 11 |
Subject |
Geography |
Chapter |
5 |
Chapter Name |
Global Climate Change |
1) Complete the chain:
A |
B | C |
1) Melting of snow | 1) Methane |
1) Flooding |
2) Effects of insolation |
2) Average temperature of the earth | 2) Agriculture |
3) Greenhouse gases | 3) Erratic rains |
3) Existence of life on earth |
4) Climate change |
4) Increase in sea level |
4) Increase in frequency of cyclones |
Answer – The completed chain will be as mentioned below : –
A |
B | C |
1) Melting of snow | 1) Increase in sea level |
1) Flooding |
2) Effects of insolation |
2) Erratic rain | 2) Increase in frequency of cyclones |
3) Greenhouse gases | 3) Methane |
3) Agriculture |
4) Climate change |
4) Average temperature of the earth |
4) Existence of life on earth |
2) Identify the incorrect factor:
1) The causes of global warming
a) Emission of greenhouse gases
b) Deforestation
c) Apparent movement of the sun
d) Industrialization
Answer – The causes of global warming – Apparent movement of the sun
2) The indicators of climate change
a) Retreat of glaciers
b) Increase in the frequency of floods
c) Increase in the frequency of cyclones
d) Increase in the minimum and maximum temperature
Answer – The indicators of climate change – Increase in the minimum and maximum temperature
3) The tools for studying climate change
a) Ice cores b) Coral reef
c) Tree rings d) Ancient forts
Answer – The tools for studying climate change – Ancient forts
4) Measures to combat climate change
a) Banning the use of pesticides and insecticides.
b) Promoting afforestation and banning deforestation
c) Banning public transport
d) Banning fossil fuels
Answer – Measures to combat climate change – banning of public transport
3) Give geographical reasons:
1) It is important to study climate change
Answer – Study of climate change has become very important rather critical because of the following reason –
Human activities have accelerated the rate of change of earth’s climate, as a result the climate change is occurring at a faster rate than ever before, which could have catastrophic consequences.
Increase in the global temperatures is causing the polar ice caps and snow to melt faster thereby the sea level is rising at an alarming rate. Also, ocean waters are warmer causing leading to a faster rate of evaporation, consequentially there are torrential rains, flash floods and frequent cyclones.
Increase in the human use of fossil fuels whose combustion is resulting in emission of green house gases like methane, carbon di-oxide etc that traps the solar heat and does not let it escape to the atmosphere, as a result it is causing increase in average temperatures. Deforestation, usage of pesticide / insecticides and fertilisers during cultivation and pollution involved in industrial activities are other causes for rapid change in climatic conditions, which need to be studied, understood and acted upon, at the earliest.
2) There is a great possibility that we may not see Maldives on the world map in the future.
Answer – Global warming is a consequence of human activities has led to rapid rise in atmospheric temperature due to which the glaciers and polar ice caps are melting quickly leading to a rise in the sea level.
The sea level has been observed to rise at a rate of about 3mm / year which is quite alarming, resulting in severe cyclones and flooding of coastal areas.
Maldives is an island country on the Indian ocean and it is likely that if the oceans continue to rise at this rate, the country may be submerged as an ill effect of climate change and global warming.
3) The snowline is retreating
Answer – Boundary between the snow covered and snow free zones are called the snow line.
Melting of ice is a very natural process which occurs by itself, but when glaciers and icebergs start melting at an alarming rate, it becomes a grim situation to worry about. There is evidence from the satellite pictures that due to global warming there are a number of retreating glaciers around the world.
Studies using satellite data from 1989 till date indicate that glaciers have retreated tremendously. The satellite images have shown the Gangotri Glacier, situated in the Uttarkashi District of Garhwal Himalayas, which is one of the largest in the Himalayas have retreated over the last 25 years by more than 850 meters, and the rate of recession has been of 76 meters from 1996 to 1999 alone (just 3 years).
This means that more ice is melting each year than being formed and on calculation it has been seen that the retreat is around 22 m per year. Scientists have co-related the receding glaciers as signs of global climate change.
Similar pictures have also been seen in the glaciers near Mt. Kilimanjaro and Alps where the glaciers have been retreating at a quite faster rate..
4) There is an increase in the frequency of droughts and cyclones
Answer – There is an increase in the frequency of occurrence of droughts and cyclones because –
Global warming is the root cause for both droughts and cyclones. As the average temperature of oceans increase, the rate of evaporation is also increased, leading to heavy rainfall at some coastal places and droughts in the interior areas.
Recent studies have revealed that the percentage of Earth’s land area undergoing serious drought has doubled since 1970s.
Global warming has resulted in heating up of the oceans, and water molecules near the sea surface tend to become more energetic and evaporate into the atmosphere more readily. Thus, the surrounding air gets more water vapour and this effect becomes stronger with each additional degree of warming. This has eventually resulted in the number of cyclones to increase in the tropical regions and so have their intensities.
4) Write short notes :
1) Bleaching of coral reefs
Answer – As temperatures change, corals throw out the algae living in their tissues which are responsible for their colour. When there is an increase in ocean temperatures by 1°- 2° C for quite a long time, there are chances of bleaching, which means that the corals turn into white.
If this happens for a long period of time, then the corals eventually die. Bleaching leads to death of large amounts of corals. Due to changes in the climatic conditions, it has been observed that more than one-fifth of the coral reefs are already lost from the ocean floors.
2) Flash floods
Answer – The number of flash floods has increased many times in the past few years and also the intensity and duration of the floods. The main reason for this is perhaps because of very heavy rainfall in one day (eg . Mumbai, in 2005; Kedarnath, in 2013, Chennai, 2015).
Overall, several cities or regions have experienced increased flooding activities due to the global climate change. Urban areas have experienced more of flash floods. Coastal cities like Venice are also facing flooding issues.
3) Tools to study Paleoclimatolgy
Answer – Paleoclimatology is the term given to the study of the weather and climate of the Earth’s past. Science as we know presently is relatively new and the scientists and meteorologists have started using instruments to measure climate and weather patterns for the past 140 years only. It is therefore impossible to predict, understand or analyse the historic climatic conditions way back millions of years, with respect to the earth’s age.
The scientists with their understanding use historical evidences called proxy data, which include tree rings, ice cores, coral reefs and ocean sediments to get an idea about the earth’s climatic conditions that might have pre-existed humans.
Coral reefs – The coral reefs are quite sensitive and react to the changes in climatic conditions. Coral skeletons are formed by extracting calcium carbonate from the sea waters. With the change in temperature of ocean water, density of calcium carbonate present in the coral skeletons tend to differ. Therefore, Coral formed in the summer (when water is warmer) has different density in comparison to coral formed in the winter (when water is comparatively cooler) and this creates distinctly different seasonal growth rings on the coral, making it a very significant tool for the scientific community.
Tree rings – Variation in patterns in tree rings occur due to variation in environmental conditions when they were formed. Therefore, by studying these variation leads to a better and systematic understanding of past environmental conditions.
Ice cores – Ice Cores are small samples of ice taken from the inner sides of the large ice sheets. Year after year, layers of snow fall over the ice sheets in Greenland and Antarctica and each layer of snow is distinctly different. Also, the summer snow tends to differs from winter snow. Each of the layers gives scientists a lot of information about the climate of that particular year.
It can further be seen that many parts of the world have experienced alternate wet and dry periods. An example for this can be seen in the fact that geological findings have shown that the desert in Rajasthan experienced wet and cool climate around 8000 years back. It had become drier some 4000 years ago after the Harappa civilisation. The earth was also known to be warmer around 500-300 million years ago and around 10,000 years ago, the last glacial period had ended. Well-preserved fossils of several animals and plants, such as the mammoth, are from this late era. However, it is very well understood that these changes in the climate in the past century are not due to the human interference as in the present.
4) Greenhouse gases
Answer – Green house gases are the gases like Nitrous oxide, Carbon-di-oxide, Carbon mono oxide, Chloro Fluro carbons (CFC), methane, water vapours and also Ozone in the earth’s atmosphere that absorbs heat from the solar radiations and do not allow it to escape as much.
Among all the green house gases, Carbon di oxide is known to absorb most of the atmospheric heat and is mainly responsible for global warming. Carbon di oxide in the atmosphere has increased due to human activities like burning of fossil fuels, oil and natural gases, and the added effect of deforestation.
Due to the increase in the amount of green house gases in the atmosphere the average temperature of the earth’s atmosphere has increased several times in the past decade and resulted in the melting of ice bergs, rise in sea level, increase in the number of cyclones, etc.
5) Answer in detail :
1) Climate change has not always been anthropogenic in nature. Explain.
Answer – At present, though human activities are a major cause behind climate change, there are some other very important natural causes for climate change, which are being mentioned as follows:
1) Amount of Solar Energy output – The amount of energy output by the Sun varies from time to time and is not constant all the time. Lower energy output can reduce amount of insolation received by the earth and this could lead to cooling down of the planet and vice versa.
2) Millankovitch oscillations – Another important cause is the Millankovitch oscillations. As we all know, the Earth revolves around the Sun in a fixed orbit. Certain variations in the earth’s orbital characteristics around the sun and also the changes in the earth’s axial tilt do occur at times. Scientists are of the opinion that these variations, alter the amount of insolation (or solar output energy) received from the sun, which in turn, might affect the climatic conditions of the earth. While, they can cause the Earth to be closer to the Sun and therefore become quite warmer or move farther away from the sun causing steep decrease in temperatures and hence Ice ages.
3) Volcanism – Volcanism is considered as another important event that causes climate change. Volcanic eruptions seem to throw lots of particulates and aerosols (especially sulphur dioxide) into the atmosphere. These aerosols while they remain in the atmosphere for a considerable period of time, spread with the wind around the world, thereby reducing the sun’s radiation and stopping it from reaching the Earth’s surface. It has further been observed that most if not all of the coldest years on record in the past two centuries have occurred in the year after major volcanic eruptions. For example, after the recent El Cion (in 1982) and Pinatubo (in 1991) volcanic eruptions, the average temperature of the earth dropped to some extent for several years.
4) Goldilocks Zone – The scientists believe that the earth is situated in a habitable zone called the Goldilocks Zone, which means that the earth is a planet that is neither too close to its star nor too far away, therefore it experiences the right temperature for life to thrive, triumph and evolve.
Previously, Earth had experienced cooler climate early in its history, when it was located in the outer reaches of this zone. In the future also, as the size of the Sun increases (with perishing hydrogen reserves) the zone will move outward over time. Such changes in the zone would cause earth to be warmer or cooler.
2) What measures will you suggest to combat climate change in your village / city.
Answer – Human activities have started to play a major role in climate changes and therefore several measures can be taken to decrease the negative effects –
1.) Minimise deforestation activities and take steps to plant more trees as plants play an important role in absorbing carbon-di-oxide from the atmosphere as they require Co2 for photosynthesis. More plants would mean that they would play a deciding role in decreasing this important Green house gas (Co2) and therefore decrease its ill effects on the environment.
2.) Motivate people for using LPG (Liquefied petroleum gas) for cooking instead of coal, or wood as fuel.
3.) In cities and urban areas, use of public transport should be encouraged against two wheelers to reduce vehicular pollution and maintain a healthier air quality index.
4.) Use of manure and other nature fertilisers prepared from cow dung, etc should be encouraged over chemical fertilisers. Similarly, natural pesticides and insecticides like neem, etc. should be used over their chemical counterparts as they enter the food cycle and also cause environmental damage. Excess use of chemicals as fertilisers and pesticides also makes the soil poorer.
5.) Ban usage of plastic in the form of bags, bottles and in all forms possible as we know that decomposition of plastic takes thousands of years and they are responsible for causing damage to our soil, oceans and even burning them is very harmful for the atmosphere.