Hey, readers in this post you will learn about Climate Change and Global Warming. We will start with basic terminologies and then deal with concepts. This topic is part of the Environment which is part of UPSC GS III paper.
- Climate: Weather of a particular location over a long period of time.
- Climate Change: Change in the usual weather of a place. This could be a change in the rain or a change in the temperature.
- Ecological Footprint: It is the increase in human demand compared to the ability of nature to produce it. Day by day human demands is increasing whereas productivity of nature is decreasing.
- Carbon Footprint: Amount of CO2 absorbed by Green House Gases (water vapour, carbon dioxide, methane, nitrous oxide and so on)
- Carbon Source: Anything that emits more carbon than it removes ex. city roads
- Carbon Sink: Anything that removes more carbon than it emits ex. forests
- Carbon Neutral: Carbon emission is equal to Carbon absorption
- Carbon sequestration: Process of removal of Carbon Dioxide and its long term source
- Biological Oxygen Demand: Amount of O2 required to decompose organic compounds
- Chemical Oxygen Demand: Amount of oxygen required to decompose both organic and inorganic compound
- WMO: World Meteorological Organisation. It is an intergovernmental organisation established by the ratification of the WMO convention. HQ is based in Geneva. Notably, it works under UNEP.
- IPCC: Intergovernmental Panel on Climate Change. It is an international body established in 1988 by WMO and UNEP.
- Conference of Parties CoP: Highest decision-making body, of IPCC on Climate.
Climate change is a change in the usual weather of a place. This could be change in rain or change in temperature of that place.
|SIGNS OF CLIMATE CHANGE||EFFECT OF CLIMATE CHANGE|
- Global sea level are rising at an alarmingly fast rate.
- Earth’s average temperature has risen by 1°C over the past 100 years
- Most importantly earth’s temperature is projected to increase by 2°C over the next 100 years
- The Paris Agreement aims to keep global warming below 2. (if x°C was preindustrial temperature then keeping it below x+2°C in next century)
CLIMATE IN RECENT PAST
Climate change is not a recent phenomenon. Variability in climate occurs all the time. Let us have a look at the recent climate change phenomena –
- Europe witnessed the Little Ice Age from 1550 to about 1850. Since then world temperature showed an upward trend. Most important cause being the Industrial Revolution,
- In the 1930s, a severe drought occurred in southwestern Great Plains of the United States, described as the dust bowl.
- The 1990s recorded the warmest temperature of the 19th Century and some of the worst floods around the world.
- Climate Change is associated with drought and flood. Consequently, crop failures cause mass migration as it happened in the case of the drought of the Sahel region from 1967-1977 (NCERT)
GLOBAL CO2 OVER THE YEARS
CAUSES OF CLIMATE CHANGE
ASTRONOMICAL CAUSES (not much significant)
- Sunspots: Are dark and cooler patches on the face of the sun. Darker and larger the patch cooler is the weather on the earth.
- Milankovitch oscillations: Because of change in the axial tilt earth wobbles (i.e. moves side by side unsteadily). This alters the insolation received from the sun. Hence alteration cause change in climate change.
- Volcanism: Volcanic eruption throws up lots of aerosols into the atmosphere. They cause alteration in the sun’s insolation. Hence cause Climate change.
- Green House Gases: Most important anthropogenic cause. Green House Gases traps longwave radiation inside the atmosphere which causes a temperature rise of the planet i.e. Global Warming.
Along with these four basic causes, there are few more phenomena which cause climate change ex. Meteorite impacts, deforestation, industries, chemical fertilisers, vehicle pollution and so on.
Global warming is increasing in the average temperature of the earth especially in the troposphere. Global warming is a tropospheric phenomenon. Global Warming is visible through changing rain patterns, rising sea levels, melting glaciers and so on.
Greenhouse effect causes heating. You can understand the Green House Effect from 2 examples given below-
- Green House: Greenhouse is a glass house which is used to grow plants especially during winter. The greenhouse is made such that light is allowed to enter but not allowed escape in short, light is trapped inside. As a result, the greenhouse warms up.
- Similarly, a car parked under the sun warms up.
In the case of the earth, the atmosphere absorbs heat and does not allow it to escape. Firstly, Sun’s longwave radiation reach the earth. The earth absorbs some amount and reflects the rest. The rest is absorbed by the Green House Gases such as CO2, water vapour, methane, nitrous oxide and so on.
In short, the GHG performs the same function that glass does in the greenhouse.
Primary GHGs are –
- Water Vapour: It is the largest contributor to the earth’s greenhouse effect.
- Carbon Dioxide: CO2 generates a little over 55% of the human-induced GH effect.
- Fluorinated Gases: Synthetic and powerful greenhouse gases.
- Methane (CH4): Brief lifetime and less concentration compared to other gases
- Nitrous Oxide (N2O): 5% of human-induced GH effect. Also produced by microbial processes.
- Ozone (O3): Acts as a GHG at ground level. Absorbs long wave radiations reflected by the earth.
EFFECTIVENESS OF GREENHOUSE GASES
The effectiveness of any given GHG molecule will depend on-
- the magnitude of the increase in its concentration
- its lifetime in the atmosphere
- the wavelength of radiation that it absorbs
Based on the above facts, for each gas, a Global Warming Potential (GWP) is calculated
GWP gives an idea about
- How long gas remains in the atmosphere?
- How strongly it absorbs energy?
GASES AND THEIR GLOBAL WARMING POTENTIAL
|GAS||LIFETIME (In Years)||RELATIVE GWP/CO2 (100 Years)|
|Perfluorocarbons||Up to 50000 yrs||7400- 12200|
|Hydrofluorocarbons||Up to 264 yrs||120- 4800|