Download UGRC 144_Session 7

UGRC 144
Science and Technology in Our
Lives/Geohazards
Session 7 – Global Climate and Climate
Change
Lecturer: Dr. Patrick Asamoah Sakyi
Department of Earth Science, UG
Contact Information: [email protected]
College of Education
School of Continuing and Distance Education
2014/2015 – 2016/2017
Session Overview
• This session introduces you to global climate and the
various evidences that suggest that, compared to the
present time, there have been changes in global
climate.
• The earth's climate is continually changing,
fluctuating between ice ages and warmer periods.
The modern debate on climate change is really about
human impact on the Earth's dynamic changing
climate.
• This session will link natural and human activities to
the Earth's changing climate.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 2
Session Outline
The key topics to be covered in the session are as
follows:
• Topic One –Evidence of Past Climate
• Topic Two – Ice Age and their possible causes
• Topic Three – Greenhouse effect and global warming
• Topic Four – Contribution of humans to the
greenhouse effect
• Topic Five –Effects of global warming
• Topic Six - Measures adopted to reduce global
warming
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 3
Reading List
• Chapter 9 of Environmental Geology 4th Edition, Wm.
C. Brown Publishers – by Carla W Montgomery (1995)
• Chapter 16 of Environmental Geology. 7th Edition.
Prentice Hall – by Edward A. Keller (1996).
• Chapter 11 of Geology and the Environment. 3rd
Edition. Brooks/Cole Thomson Learning – by Pipkin, B.
W. and Trent, D. D. (2001)
• Read Unit 2, Sections 1&2 of UGRC 140 II Geohazards
– Institute of Continuing and Distance Education.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 4
Topic One
EVIDENCE OF PAST CLIMATE
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 5
Evidence of Past Climate
• Climate and Weather
– Weather is the short term, normal day-to-day,
atmospheric conditions which prevail at a given
place at a given time
– The weather can be described as; stormy, rainy,
hot, windy, humid, and sunny.
– Climate is the "average weather" of an area
over a much longer time span, often hundreds
or thousands of years
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 6
Evidence of Past Climate
• The four main types of evidence indicating climatic
conditions that existed in the past are;
– Geological (use of aerial photos reveal desert areas that
were previously occupied by vegetation).
– Geomorphological (e.g. features such as river deltas
also show where rivers entered the ocean or a lake. )
– Chemical evidence shows variations in the ratios of
isotopes in fossils present in sediments and sedimentary
rocks and ocean sediment cores)
– Paleontological evidence shows changes in the
geographical distribution of fossils (dead plants and
animals
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Dr. Patrick A. Sakyi, Dept. of Earth Science
Topic Two
ICE AGE AND THEIR POSSIBLE
CAUSES
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 8
Ice Age and their possible causes
• Ice Age refers to time in recent geologic past when
extensive continental glaciers covered large areas than
they do now.
• It is caused by fluctuations in the amount of incoming
solar radiation are the most likely cause of ice age, or
locking of incoming solar radiation by particles such as
volcanic dust or sulphuric-acid droplet in the
atmosphere.
• This can result in the cooling which can induce the start
of an ice age.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 9
Topic Three
GREENHOUSE EFFECT AND GLOBAL
WARMING
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 10
Greenhouse Effect and Global
Warming
• The temperature of the earth depends on the
amount of energy we receive from the sun
and the amount of energy lost back out to
space.
• This energy is called radiation, which is made
up of X-rays, ultraviolet (UV), visible light and
infrared (IR).
• Of major concern to us are the UV and IR.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 11
Greenhouse Effect and Global
Warming
• UV is very harmful so a significant portion is
absorbed in the atmosphere by some of the gases
and the ozone layer before it reaches the earth.
• The IR is also responsible for warming the land
surface, which in turn radiates heat into the
atmosphere.
• Thus, the earth surface absorbs the solar radiation
and releases it back to the atmosphere as infrared
radiation, some of which goes back into space.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 12
Greenhouse Effect and Global
Warming
• This process helps to keep the temperature of the earth
at level conducive to life.
• The problem however has to do with the increased
concentration in the atmosphere of greenhouse gases
such;
– nitrous oxide,
– chlorofluorocarbons,
– methane (CH4) and
– carbon dioxide (CO2)
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 13
Greenhouse Effect and Global
Warming
• Some of the infrared radiation emitted by the earth
is absorbed by these gases in the atmosphere that
subsequently re-emit the energy as heat back
towards the earth’s surface.
• Trapping of infrared radiation in the atmosphere is
known as enhanced greenhouse effect and it
increases the average temperature of the earth.
• Thus, the more greenhouse gases we have in the
atmosphere, the likelihood is that global warming
will increase.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 14
Greenhouse Effect and Global
Warming
• Emission of infrared radiation
emitted by the earth
• Absorption of IR radiation by
greenhouse gases in the
atmosphere
• Subsequently re-emission the
energy as heat back towards
the earth’s surface.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 15
Topic Four
CONTRIBUTION OF HUMANS TO
THE GREENHOUSE EFFECT
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 16
Contribution of humans to the
greenhouse effect
• Man-made activities contribute significantly to the
greenhouse effect, resulting in global warming. The
activities include;
– Burning of natural gas, coal and oil, including gasoline
for automobile engines, which raises the level of
carbon dioxide in the atmosphere.
– Many factories produce long-lasting industrial gases
that do not occur naturally, yet contribute significantly
to the enhanced greenhouse effect and global
warming.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 17
Contribution of humans to the
greenhouse effect
– Deforestation also contributes to global warming.
Trees use carbon dioxide and give off oxygen in its
place, which helps to create the optimal balance of
gases in the atmosphere.
– Population growth is another factor in global warming,
because as more people use fossil fuels for heat,
transportation and manufacturing the level of
greenhouse gases continues to increase.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 18
Contribution of humans to the
greenhouse effect
– Some farming practices and land-use
changes increase the levels of methane and
nitrous oxide.
– As more farming occurs to feed millions of
new people, more greenhouse gases enter
the atmosphere.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 19
Topic Five
EFFECTS OF GLOBAL WARMING
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 20
Effects of Global Warming
• Increase in the global temperature would lead to
significant climate and weather changes, thereby
affecting;
– cloud cover,
– precipitation,
– wind patterns,
– frequency and severity of storms
– duration of seasons
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 21
Effects of Global Warming
• Sea Level Rise - Rising temperatures may cause more
ice to melt into water which will intend flow into the
oceans and seas
• Many of the world’s endangered species would
become extinct as rising temperatures would change
their habitat.
• Spread of Disease - Certain vector-borne diseases
carried by animals or insects, such as malaria, would
become more widespread as warmer conditions
expand their range
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 22
Topic Six
MEASURES ADOPTED TO REDUCE
GLOBAL WARMING
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 23
Measures adopted to reduce global
warming
• To lessen the long-term effects of global
warming, many nations, communities and
individuals are taking action now to reduce
greenhouse gas emissions and slow global
warming.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 24
Measures adopted to reduce global
warming
• Among the measures taken are;
– Reducing dependence on fossil fuels (e.g., coal,
petroleum and natural gas).
– Increasing the use of renewable energy (e.g., solar,
wind, and geothermal heat).
– Expanding our forests to take up carbon dioxide in the
atmosphere.
– Making lifestyle choices that help to sustain the
environment.
Dr. Patrick A. Sakyi, Dept. of Earth Science
Slide 25
Summary
• In this session we have learnt that greenhouse gases ( e., CH4, CO2) in
the atmosphere absorb infrared radiation and re-emit the energy
towards the earth’s surface. This increases the average temperature of
the earth, resulting in global warming.
• We also discussed the human activities that contribute to the
greenhouse effect, and these include; the burning of fossil fuels,
deforestation, industrial gases and population growth.
• The resultant greenhouse effect will cause the rise in global sea level,
flooding in coastal areas, spread of vector-borne diseases.
• Among the measures that can be adopted to curtail greenhouse gas
emission include; reducing dependence on fossil fuels, increase the use
of renewable energy, expanding forests and making lifestyle choices that
help to sustain the environment
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Dr. Patrick A. Sakyi, Dept. of Earth Science
END
Dr. Patrick A. Sakyi, Dept. of Earth Science
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