climate change

1. CAUSES OF
CLIMATE
CHANGE
E-Content: Environmental Science
Faculty Name: Dr Sanjay Marale
Student Names: Harshita Jain, Sakshi Joshi
Shivpreet Pannu, Shweta Goel
Kamala Nehru College, University of Delhi

2. WHAT IS CLIMATE CHANGE?
 Climate change is the long-term alteration of
temperature and typical weather patterns in a
place. Climate change could refer to a particular
location or the planet as a whole.
 Often climate change refers
specifically to the rise in
global temperatures from
the mid 20th century to
present.

4. VOLCANIC ERUPTIONS
 When a volcano erupts it throws out large volumes of
sulphur dioxide (SO2), water vapour, dust, and ash
into the atmosphere. Although the volcanic activity
may last only a few days, yet the large volumes of
gases and ash can influence climatic patterns for
years.
 Millions of tonnes of sulphur dioxide gas can reach
the upper levels of the atmosphere (called the
stratosphere) from a major eruption. The gases and
dust particles partially block the incoming rays of the
sun, leading to cooling.

6. OCEAN CURRENTS
 An ocean current is a continuous movement
of ocean water from one place to another. Ocean
currents are created by wind, water temperature, salt
content, and the gravity of the moon.
 The oceans are a major component of the climate
system. They cover about 71% of the Earth and
absorb about twice as much of the sun's radiation as
the atmosphere or the land surface. Ocean currents
move vast amounts of heat across the planet -
roughly the same amount as the atmosphere does.

7. CONT…
 Ocean currents act much like a conveyor belt,
transporting warm water and precipitation from the
equator toward the poles and cold water from the
poles back to the tropics.
 Thus, ocean currents
regulate global climate,
helping to counteract the
uneven distribution of
solar radiation reaching
Earth's surface.

9. EARTH ORBITAL CHANGES
 The earth makes one full orbit around the sun each
year. It is tilted at an angle of 23.5° to the
perpendicular plane of its orbital path. For one half of
the year when it is summer, the northern hemisphere
tilts towards the sun. In the other half when it is winter,
the earth is tilted away from the sun. If there was no
tilt we would not have experienced seasons.
 Changes in the tilt of the earth can affect the severity
of the seasons - more tilt means warmer summers
and colder winters; less tilt means cooler summers
and milder winters.

10. CONT…
 The Earth’s orbit around the Sun is an ellipse, not a
circle but the ellipse changes shape.
 Sometimes it is almost circular and the Earth stays
approximately the same distance from the Sun as it
progresses around its orbit.
 At other times the ellipse is more pronounced so
that the Earth moves closer and further away from
the sun as it orbits.
 When the Earth is closer to the sun our climate is
warmer.

13. SOLAR VARIATION
 “Solar Variation” describes the change in the Sun’s
radiation output. The Sun is fundamentally the source
of all energy on the Earth and so regardless of other
limiting and even amplifying factors, if the amount of
radiation from the Sun is changed then it has a knock
on effect on insolation and therefore temperature.
 It has been suggested that changes in solar output
might affect our climate—both directly,
by changing the rate of solar heating of the Earth
and atmosphere, and indirectly, by changing cloud
forming processes.

14. CONT…
 Over the past century, Earth's average temperature
has increased by approximately 0.6 degrees
Celsius (1.1 degrees Fahrenheit). Solar heating
accounts for about 0.15 C, or 25 percent, of this
change, according to computer modeling results
published by NASA Goddard Institute for Space
Studies researcher David Rind in 2004.

16. HUMAN CAUSES
 The Industrial Revolution in the 19th century saw the
large-scale use of fossil fuels for industrial activities.
These industries created jobs and over the years,
people moved from rural areas to the cities. This trend
is continuing even today. More and more land that
was covered with vegetation has been cleared to
make way for houses. Natural resources are being
used extensively for construction, industries,
transport, and consumption. Consumerism (our
increasing want for material things) has increased by
leaps and bounds, creating mountains of waste. Also,
our population has increased to an incredible extent.

18. CONT…
 All this has contributed to a rise in greenhouse gases
in the atmosphere. Fossil fuels such as oil, coal and
natural gas supply most of the energy needed to run
vehicles, generate electricity for industries,
households, etc. The energy sector is responsible for
about ¾ of the carbon dioxide emissions, 1/5 of the
methane emissions and a large quantity of nitrous
oxide. It also produces nitrogen oxides (NOx) and
carbon monoxide (CO) which are not greenhouse
gases but do have an influence on the chemical
cycles in the atmosphere that produce or destroy
greenhouse gases.

20. GREENHOUSE EFFECT
 The greenhouse effect is defined as when the Earth's
atmosphere becomes thick with gases and
substances which trap the sun's radiation, making the
Earth warmer.
 An example of the greenhouse effect is global
warming.
 Carbon dioxide is undoubtedly, the most important
greenhouse gas in the atmosphere. Changes in land
use pattern, deforestation, land clearing, agriculture,
and other activities have all led to a rise in the
emission of carbon dioxide, giving rise to greenhouse
effect.

22. BURNING OF FOSSIL FUELS,
DEFORESTATION, INDUSTRIAL GASES AND
COAL MINING
 Burning fossil fuels , coal mining , deforestation and other
activities has contributed to more and more carbon dioxide
building up in the atmosphere. The build-up of carbon dioxide
in the atmosphere is driving global warming, as it traps heat in
the lower atmosphere. Carbon dioxide levels are now at their
highest levels in human history.

23. When forests are cleared or burnt, stored carbon is released into the
atmosphere, mainly as carbon dioxide. Averaged over 2015 – 2017, global
loss of tropical forests contributed about 4.8 billion tonnes of carbon dioxide
per year.

24. THE END