Climate Change and Global Warming: Notes for Exams
Climate change notes for exams: the greenhouse effect and its gases, impacts of warming, the UNFCCC, Kyoto Protocol, Paris Agreement and India's action plan.
By GK24 Editorial Team· Published · 5 min read
Weather is the state of the atmosphere at a place at a given moment, while climate is the average of weather over a long period, usually thirty years or more. Climate change means a lasting change in that average, and global warming is the part of it that consists of a rise in the average surface temperature of the earth. The climate of the earth has changed many times through ice ages and warm periods, but the change under discussion today is different because it is rapid and is driven by human activity, above all the burning of coal, oil and natural gas since the industrial revolution.
The greenhouse effect
Short wave radiation from the sun passes easily through the atmosphere and warms the surface of the earth. The warmed surface sends the energy back as long wave infrared radiation, and certain gases in the atmosphere absorb a part of this outgoing radiation and radiate it back downwards. This trapping of heat is the greenhouse effect, named after the glass house that stays warm inside. It is a natural and necessary process; without it the average temperature of the earth would be far below freezing and life as we know it could not exist. The problem is the enhanced greenhouse effect, the strengthening of this natural blanket by gases that human activity has added to the air.
| Greenhouse gas | Main human sources | Point to remember |
|---|---|---|
| Carbon dioxide | Burning of coal, oil and gas; cement making; deforestation | Released in the largest quantity; the reference gas whose global warming potential is taken as one |
| Methane | Paddy fields, cattle, landfills, coal mines, leaks from gas pipelines | Far stronger than carbon dioxide over a century, but stays in the air for a much shorter time |
| Nitrous oxide | Nitrogen fertilisers, burning of fuel and biomass | Also destroys stratospheric ozone |
| Fluorinated gases | Refrigeration, air conditioning, electrical switchgear, industry | Sulphur hexafluoride has the highest global warming potential of the gases in the Kyoto basket |
| Water vapour | Natural evaporation | The most abundant greenhouse gas, but its amount is controlled by temperature rather than by emissions |
Evidence and impacts
The signs of a warming world are consistent across measurements. Glaciers in the Himalaya, the Alps and the Andes are retreating, the sea ice of the Arctic is shrinking, and sea level is rising both because ocean water expands as it warms and because land ice is melting into it. The oceans are also becoming more acidic as they absorb carbon dioxide, which harms corals and shelled organisms. Coral bleaching, the loss of the algae that live inside coral and give it colour, follows spells of unusually warm water. Heat waves, heavy rainfall events, droughts and cyclones of high intensity are becoming more frequent, and species are moving to higher latitudes and higher altitudes. For India the risks are concentrated: an unreliable monsoon on which farming depends, flooding of a long and densely settled coastline, the melting of Himalayan glaciers that feed the northern rivers, and heat that directly threatens outdoor workers.
The global response
- IPCC: the Intergovernmental Panel on Climate Change, set up in 1988 by the World Meteorological Organization and the United Nations Environment Programme. It does no research of its own; it assesses published science and issues assessment reports.
- UNFCCC: the United Nations Framework Convention on Climate Change, adopted at the Earth Summit at Rio de Janeiro in 1992. It rests on the principle of common but differentiated responsibilities, and its members meet at the Conference of the Parties, the COP.
- Kyoto Protocol: adopted in 1997 and in force from 2005. It set binding emission cuts for the developed countries listed in Annex I only, and created the market mechanisms of emissions trading, joint implementation and the clean development mechanism.
- Paris Agreement: adopted at COP21 in Paris in 2015 and in force from 4 November 2016. It applies to all countries, asks each to submit its own nationally determined contribution, and aims to hold the rise in global average temperature well below two degrees Celsius above pre-industrial levels while pursuing efforts to limit it to one and a half degrees.
- Montreal Protocol: agreed in 1987 to phase out ozone depleting substances such as chlorofluorocarbons. Its Kigali Amendment of 2016 brought hydrofluorocarbons, which are greenhouse gases, into its schedule.
What India is doing
India released the National Action Plan on Climate Change in 2008, with eight national missions: the solar mission, enhanced energy efficiency, sustainable habitat, water, sustaining the Himalayan ecosystem, a green India, sustainable agriculture and strategic knowledge for climate change. India and France launched the International Solar Alliance at the Paris conference in 2015, and its headquarters is at Gurugram in Haryana. At the Glasgow conference in 2021 India announced a target of net zero emissions by the year 2070, along with pledges on renewable capacity and emission intensity. Other steps include the energy conservation programme with its star labelling, the promotion of electric vehicles, compressed biogas and green hydrogen, and afforestation under the green India mission.
Global warming is not ozone depletion
These two problems are constantly confused in examinations, and they are separate. Global warming is the trapping of outgoing heat in the lower atmosphere by greenhouse gases. Ozone depletion is the thinning of the ozone layer in the stratosphere by chlorofluorocarbons and similar chemicals, which lets in more harmful ultraviolet radiation and causes skin cancer, cataract and damage to crops. The treaty for ozone is the Montreal Protocol and the treaties for climate are the Kyoto Protocol and the Paris Agreement. The link between them is that some substances, such as hydrofluorocarbons, matter for both.
Exam Point of View
Most questions here are on the agreements and the institutions: which year, which city, which body set up the IPCC, which protocol binds only developed countries, and what the Paris temperature goal is. The second group is on the gases, where the gas released in the largest quantity, the gas with the highest global warming potential and the sources of methane are asked. The third group is the distinction between global warming and ozone depletion, which is asked almost every year in some form. The traps are treating the Montreal Protocol as a climate treaty, mixing the years 1987, 1992, 1997 and 2015, and saying that the greenhouse effect itself is harmful when it is the enhanced effect that is the problem.
Important Facts
| Greenhouse effect | Trapping of outgoing infrared radiation by gases in the atmosphere |
|---|---|
| Chief greenhouse gases | Water vapour, carbon dioxide, methane, nitrous oxide and fluorinated gases |
| Reference gas | Carbon dioxide, whose global warming potential is taken as one |
| Highest global warming potential | Sulphur hexafluoride, among the gases of the Kyoto basket |
| IPCC | Set up in 1988 by the WMO and UNEP; issues assessment reports |
| UNFCCC | Adopted at the Rio Earth Summit, 1992; parties meet at the COP |
| Kyoto Protocol | Adopted 1997, in force 2005; binding only on Annex I countries |
| Kyoto mechanisms | Emissions trading, joint implementation, clean development mechanism |
| Paris Agreement | Adopted at COP21 in 2015, in force 4 November 2016 |
| Paris goal | Well below two degrees Celsius, pursuing efforts towards one and a half degrees |
| Montreal Protocol | 1987, on ozone depleting substances; Kigali Amendment of 2016 on HFCs |
| India's action plan | National Action Plan on Climate Change, 2008, with eight missions |
| International Solar Alliance | Launched by India and France in 2015; headquarters at Gurugram |
| India's net zero target | The year 2070, announced at the Glasgow conference in 2021 |
Practice MCQs on this topic
When carbon dioxide is increased in the atmosphere, it leads to ________.
- A.Global warming
- B.Air pressure
- C.Conservation
- D.Rains
Show answer
Carbon dioxide is a greenhouse gas: it lets in the short wave radiation of the sun but absorbs a part of the long wave infrared radiation that the warmed earth sends back, and radiates it downwards again.
Read the full explanation →The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by which two organisations?
- A.UNESCO and FAO
- B.The World Meteorological Organization and the United Nations Environment Programme
- C.The World Bank and the IMF
- D.WHO and the United Nations Development Programme
Show answer
The two bodies set up the panel in 1988 so that governments would have a single authoritative summary of what science says about climate change.
Read the full explanation →The United Nations Framework Convention on Climate Change was adopted at which conference?
- A.The Stockholm Conference, 1972
- B.The Earth Summit at Rio de Janeiro, 1992
- C.The Johannesburg Summit, 2002
- D.The Copenhagen Conference, 2009
Show answer
The United Nations Conference on Environment and Development, popularly called the Earth Summit, produced the Framework Convention on Climate Change along with the Convention on Biological Diversity and Agenda 21.
Read the full explanation →The Kyoto Protocol, which set binding emission targets, was adopted in which year?
- A.1987
- B.1992
- C.1997
- D.2005
Show answer
The Kyoto Protocol was adopted at the third Conference of the Parties held in the Japanese city of Kyoto in 1997, and it came into force in 2005 after enough countries had ratified it.
Read the full explanation →Under the Paris Agreement of 2015, countries agreed to hold the rise in global average temperature to:
- A.Well below 2 degrees Celsius above pre-industrial levels, pursuing efforts towards 1.5 degrees
- B.Exactly 3 degrees Celsius above present levels
- C.Below 5 degrees Celsius by the year 2100
- D.No numerical limit at all
Show answer
The Paris Agreement, adopted at the twenty-first Conference of the Parties in 2015 and in force from November 2016, commits its parties to holding the increase in the global average temperature to well below two degrees Celsius above pre-industrial levels and to pursuing efforts to limit the increase to one…
Read the full explanation →Which of the following gases has the highest global warming potential?
- A.Carbon dioxide
- B.Methane
- C.Nitrous oxide
- D.Sulphur hexafluoride
Show answer
Global warming potential measures how much heat a mass of a gas traps over a chosen period compared with the same mass of carbon dioxide, which is given the value one.
Read the full explanation →The National Action Plan on Climate Change of India, released in 2008, consists of how many national missions?
- A.Five
- B.Six
- C.Eight
- D.Ten
Show answer
The National Action Plan on Climate Change was released in 2008 and is built around eight national missions: the National Solar Mission, the National Mission for Enhanced Energy Efficiency, the National Mission on Sustainable Habitat, the National Water Mission, the National Mission for Sustaining the Himalayan Ecosystem, the National Mission…
Read the full explanation →The Montreal Protocol is related to which environmental problem?
- A.Depletion of the ozone layer
- B.Conservation of wetlands
- C.Trade in endangered species
- D.Movement of hazardous waste
Show answer
The Montreal Protocol was agreed in 1987 under the Vienna Convention to phase out the substances that destroy stratospheric ozone, chiefly chlorofluorocarbons used in refrigeration, air conditioning and aerosol sprays.
Read the full explanation →The headquarters of the International Solar Alliance is located at:
- A.Paris, France
- B.Gurugram, India
- C.Nairobi, Kenya
- D.Abu Dhabi, United Arab Emirates
Show answer
The International Solar Alliance was launched jointly by India and France at the Paris climate conference in 2015 to promote solar energy among countries that lie largely between the tropics, and its secretariat was established at the campus of the National Institute of Solar Energy at Gwal Pahari in Gurugram…
Read the full explanation →Which of the following is NOT a consequence of global warming?
- A.Rise in sea level
- B.Retreat of glaciers
- C.Coral bleaching
- D.Increased ultraviolet radiation reaching the surface
Show answer
That is the consequence of ozone depletion, a separate problem caused by chlorofluorocarbons thinning the ozone layer in the stratosphere, and it is addressed by the Montreal Protocol.
Read the full explanation →Frequently Asked Questions
What is the difference between the greenhouse effect and global warming?
The greenhouse effect is the natural process by which certain gases in the atmosphere absorb heat radiated by the earth and send part of it back, keeping the planet warm enough for life. Global warming is the rise in the average surface temperature caused by the strengthening of that effect as human activity adds more of these gases. In short, the greenhouse effect is the mechanism and global warming is the result of its enhancement.
How is the Kyoto Protocol different from the Paris Agreement?
The Kyoto Protocol of 1997 placed legally binding emission reduction targets on developed countries listed in Annex I alone, with no obligation on developing countries, and it worked through market mechanisms. The Paris Agreement of 2015 applies to every country, but the targets are not imposed from outside; each country submits its own nationally determined contribution and reports on it. Kyoto was top down and limited, Paris is universal and built from below.
Why is the global warming potential of a gas important?
Global warming potential compares how much heat a given mass of a gas traps over a chosen period, usually a hundred years, with the heat trapped by the same mass of carbon dioxide, which is given the value one. It lets emissions of different gases be added together as carbon dioxide equivalent. Methane and nitrous oxide have much higher potentials than carbon dioxide, and sulphur hexafluoride the highest of the Kyoto basket, so even small quantities matter.
Which are the eight missions of the National Action Plan on Climate Change?
They are the National Solar Mission, the National Mission for Enhanced Energy Efficiency, the National Mission on Sustainable Habitat, the National Water Mission, the National Mission for Sustaining the Himalayan Ecosystem, the National Mission for a Green India, the National Mission for Sustainable Agriculture and the National Mission on Strategic Knowledge for Climate Change. The plan was released in 2008 and the missions cover both cutting emissions and adapting to change.
Does the ozone hole cause global warming?
No, they are different problems. The ozone layer in the stratosphere absorbs ultraviolet radiation, and its thinning by chlorofluorocarbons lets more ultraviolet reach the surface, causing skin cancer, cataract and crop damage. Global warming is the trapping of outgoing heat in the lower atmosphere by greenhouse gases. They are dealt with by different treaties, the Montreal Protocol for ozone and the Paris Agreement for climate, though a few chemicals such as hydrofluorocarbons belong to both stories.
Sources
- Contemporary India II (Class X), chapter on minerals and energy resources — NCERT
- Fundamentals of Physical Geography (Class XI), chapter on the composition and structure of the atmosphere — NCERT
