Greenhouse Effect and Climate Change part 1

41. Methane is emitted from which of the following? [U.P.P.C.S. (Pre) 2018]

(a) Paddy fields only
(b) Termitary only
(c) Both from (a) and (b)
(d) None of the above

Correct Answer: (c) Both from (a) and (b)

Solution:Methane (CH4) is emitted by natural resources such as wetlands as well as human activities.
Natural Resources - Wetlands are the largest source, emitting CH4 from bacteria that decompose organic materials in the absence of oxygen. Smaller sources include termites, oceans, sediments, volcanoes and wildfires.
Human Induced -
a. Agriculture - Domestic live stocks such as cattle, produce large amounts of CH4. Paddy cultivation and storage of manure in lagoons also releases methane. Globally, the agriculture sector is the primary source of CH4 emission.
b. Industry - Methane is the primary component of natural gas.
c. Waste from Home and businesses - Methane is generated from the decomposition of waste in landfills.

42. The gas, which is emitted in the paddy fields and increase the earth's temperature is : [U.P.P.C.S (Pre) 2019]

(a) Nitrogen
(b) Carbon dioxide
(c) Carbon monoxide
(d) Methane

Correct Answer: (d) Methane

Solution:Methane (CH4) is emitted by natural resources such as wetlands as well as human activities.
Natural Resources - Wetlands are the largest source, emitting CH4 from bacteria that decompose organic materials in the absence of oxygen. Smaller sources include termites, oceans, sediments, volcanoes and wildfires.
Human Induced -
a. Agriculture - Domestic live stocks such as cattle, produce large amounts of CH4. Paddy cultivation and storage of manure in lagoons also releases methane. Globally, the agriculture sector is the primary source of CH4 emission.
b. Industry - Methane is the primary component of natural gas.
c. Waste from Home and businesses - Methane is generated from the decomposition of waste in landfills.

43. The gas which is produced by paddy fields and is involved in global warming is? [U.P.P.C.S. (Mains) 2017]

(a) Chlorine
(b) Methane
(c) Carbon dioxide
(d) Hydrogen sulphide

Correct Answer: (b) Methane

Solution:Methane (CH4) is emitted by natural resources such as wetlands as well as human activities.
Natural Resources - Wetlands are the largest source, emitting CH4 from bacteria that decompose organic materials in the absence of oxygen. Smaller sources include termites, oceans, sediments, volcanoes and wildfires.
Human Induced -
a. Agriculture - Domestic live stocks such as cattle, produce large amounts of CH4. Paddy cultivation and storage of manure in lagoons also releases methane. Globally, the agriculture sector is the primary source of CH4 emission.
b. Industry - Methane is the primary component of natural gas.
c. Waste from Home and businesses - Methane is generated from the decomposition of waste in landfills.

44. Among the following crops, which one is the most important anthropogenic source of both Methane and nitrous oxide? [I.A.S. (Pre) 2022]

(a) Cotton
(b) Rice
(c) Sugarcane
(d) Wheat

Correct Answer: (b) Rice

Solution:Agriculture is estimated to account for 10%-20% of anthropogenic greenhouse gas (GHG) emissions worldwide. In 2005, it accounted for 50% and 60% of the total anthropogenic methane (CH₄) and nitrous oxide (N₂O) emissions, respectively. Rice paddies are considered one of the most important sources of methane and nitrous oxide emissions, which have attracted considerable attention due to their contribution to global warming.

Anthropogenic Sources of Methane and Nitrous Oxide

Methane:

Agriculture: Rice cultivation, livestock production, and manure management are all major sources of methane emissions from agriculture.
Energy: Methane is released during the production, transportation, and storage of fossil fuels.
Waste management: Methane is produced when organic waste decomposes in landfills.
Biomass burning: Burning forests, grasslands, and other biomass also releases methane into the atmosphere.

Nitrous oxide:

Agriculture: The use of nitrogen fertilizers and manure on agricultural land is the largest source of nitrous oxide emissions.
Industry: Nitrous oxide is also emitted from certain industrial processes, such as the production of nitric acid and adipic acid.
Energy: Nitrous oxide is released from the combustion of fossil fuels, especially in power plants and vehicles.

45. The greenhouse gas liberated by cud-chewing animals is - [Uttarakhand P.C.S. (Pre) 2005]

(a) Carbon dioxide
(b) Methane
(c) C.F.C.
(d) Nitrous oxide

Correct Answer: (b) Methane

Solution:Methane (CH4) is also called Marsh Gas which source is biogas, bacterial decomposition and cud-chewing animals. This is a greenhouse gas which pollutes the air. Methane is a potent greenhouse gas, responsible for about 30% of the global temperature rise since the Industrial Revolution. Its atmospheric concentration is now 2.5 times higher than in the preindustrial era and is rising faster than other greenhouse gases. The three major anthropogenic sources of methane emissions are agriculture, energy, and waste sectors. The energy sector -comprising oil, natural gas, coal, and bioenergy - accounts for over 35% of human-induced methane emissions.

46. Human activities in the recent past have caused the increased concentration of carbon dioxide in the atmosphere, but a lot of it does not remain in the lower atmosphere because of : [I.A.S. (Pre) 2011]

1. Its escape into the outer stratosphere
2. The photosynthesis by phytoplankton in the oceans.
3. The trapping of air in the polar ice caps.

Which of the statements given above is/are correct?

(a) 1 and 2
(b) 2 only
(c) 2 and 3
(d) 3 only

Correct Answer: (b) 2 only

Solution:Human activities in the recent past have caused the increased concentration of carbon dioxide in the atmosphere but a lot of it does not remain in the lower atmosphere because of the photosynthesis by phytoplankton in the oceans and plants on the land, in which carbon dioxide is absorbed.

It is a colourless gas having a faint sharp odour and a sour taste. It is an important heat-trapping gas, also known as a greenhouse gas. It comes from the extraction and burning of fossil fuels (such as coal, oil, and natural gas), from wildfires, and natural processes like volcanic eruptions. It is one of the most important greenhouse gas (GHG) in the atmosphere and is the primary driver of anthropogenic climate change.

The presence of the gas in the atmosphere keeps some of the radiant energy received by Earth from being returned to space, thus producing the so-called greenhouse effect. Carbon dioxide is used as a refrigerant, in fire extinguishers, for inflating life rafts and life jackets, blasting coal, foaming rubber and plastics, promoting the growth of plants in greenhouses, immobilizing animals before slaughter, and in carbonated beverages.

47. Which of the following statements are correct about the deposits of 'methane hydrate'? [I.A.S. (Pre) 2019]

1. Global warming might trigger the release of methane gas from these deposits.
2. Large deposits of methane hydrate' are found in Arctic Tundra and under the seafloor.
3. Methane in atmosphere oxidizes to carbon dioxide after a decade or two.

Select the correct answer using codes given below :

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Correct Answer: (d) 1, 2 and 3

Solution:Methane hydrate is a crystalline solid which contains a Methane molecule surrounded by water molecules. Methane hydrate usually exist in form of 'Ice'. Global warming might trigger the release of methane gas from these deposits. Large deposits of 'methane hydrate' have been found in Arctic Tundra and under the seafloor.
Methane is relatively short-lived in the atmosphere. It oxidizes in atmosphere into Carbon dioxide after a decade or two. It also contributes into green house effect on the earth. Hence option (d) is the correct answer.

48. Due to their extensive rice cultivation, some regions may be contributing to global warming. Io what possible reason/ reasons is/are this attributable? [I.A.S. (Pre) 2010]

1. The anaerobic conditions associated with rice cultivation cause the emission of methane.
2. When nitrogen-based fertilizers are used, nitrous oxide is emitted from the cultivated soil.

Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer: (c) Both 1 and 2

Solution:The anaerobic conditions associated with rice cultivation cause the emission of methane. When nitrogen-based fertilizers are used, nitrous oxide is emitted from the cultivated soil. Hence both statements given above are correct.

Flooded rice fields create ideal conditions for anaerobic bacteria to thrive and produce methane (CH₄) from the decomposition of organic matter, such as rice straw and roots. Methane is a powerful greenhouse gas, contributing significantly to global warming.

Nitrogen-based fertilizers, often used in rice cultivation, can be converted into nitrate, which can then be further converted into nitrous oxide (N₂O) through a process called denitrification. Nitrous oxide is also a potent greenhouse gas.

Several factors influence the extent of methane and nitrous oxide emissions, including soil type, water management practices, fertilizer application rates, and the presence of other microorganisms.

49. As a result of global warming there has been : [U.P.P.C.S. (Pre) 2001, 2003, U.P.U.D.A/L.D.A. (Pre) 2002]

1. Better global communication
2. Melting of glaciers
3. Flowering of mango trees before times
4. Adverse impact on health

Select your answer from the code given below :
Codes :

(a) 1, 2 and 3 are correct
(b) 2, 3 and 4 are correct
(c) 1, 2 and 4 are correct
(d) 1, 3 and 4 are correct

Correct Answer: (b) 2, 3 and 4 are correct

Solution:As a result of global warming, glaciers are melting worldwide. Species that depend on one another may become out of sync. For example, plants could bloom earlier than their pollinating insects become active. Global warming would have an adverse impact on human health. The main categories of health risks include (i) Direct-acting effects (ii) Impacts mediated via climate-related changes in ecological systems and relationship (eg. crop fields, mosquito ecology, marine productivity).

50. Which of the following are the impacts of Global warming? [U.P.P.C.S. (Pre) 2020]

1. Rise in sea level
2. melting of glaciers
3. Spread of diseases
4. Bleaching of coral reefs

Select the correct answer using the codes given below :
Codes :

(a) 1, 2 and 3 only
(b) 2 and 3 only
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4

Correct Answer: (d) 1, 2, 3 and 4

Solution:Global warming causes climate change which poses a serious threat to life on the earth. Rise in sea level, melting of glaciers, spread of diseases and bleaching of coral reefs are the impacts of global warming.

Global warming refers to the increase in the Earth's average temperature, primarily due to human activities. This phenomenon, commonly linked with climate change, results from the excessive emission of greenhouse gases (GHGs) into the atmosphere.

While global warming can have multiple causes, human interference-such as burning fossil fuels, deforestation, and industrial activities-is the most significant factor.Global warming is driven by natural and anthropogenic (human-induced) causes. While some factors are part of Earth's natural climate cycles, human activities have accelerated the warming process in recent centuries, causing significant environmental impacts.