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1. climate change

2. Climate and climate change
 Climate = a region’s long-term pattern of atmospheric
conditions
 Global climate change = changes in Earth’s climate,
including temperature, precipitation, and other variables
 Global warming = an increase in Earth’s average surface
temperature
 Climate changes naturally, but the recent rapid
warming of the planet and its change in
atmospheric composition are widely thought to be
due to human activities.

3. Three factors influence Earth’s climate more than all
others combined:
1.The sun, which provides most of Earth’s energy
2.The atmosphere, which both absorbs energy from the sun
and reflects it back into space
3. The oceans, which stores and transports heat and moisture
Factors that influence climate

4. Greenhouse gases
 Atmospheric gases that absorb the emanating
radiation are greenhouse gases.
 By absorbing and re-emitting this radiation, they
warm Earth’s atmosphere and surface, like a
greenhouse.
 This is popularly called the greenhouse effect.
 Global warming potential = the relative ability of
one molecule of a given greenhouse gas to contribute
to global warming.

5. What is climate change?
A change in climate which is attributed directly or
indirectly to human (anthropogenic) activity that
alters the composition of the global atmosphere and
which is in addition to natural climate variability
observed over a given or noticeable period of time.

6. The Earth’s Changing Climate
 The climate is always changing
 Evidence shows that climate has changed in the past, and
nothing suggests that it will not continue to change
 The study of the geological evidence left behind by
advancing and retreating glaciers is one factor suggesting
that global climate has undergone slow but continuous
changes
 To reconstruct past climates, scientists must examine and
then carefully piece together all the available evidence

7. INTRODUCTION
The green house effect and climate change
• Estimates indicate that since 1991, the global
atmosphere concentration of carbon dioxide has been
increasing at a rate of about 1.8 parts per million or
0018% per year.
• These trace gases in the atmosphere notably carbon
dioxide, nitrous oxide and methane called “greenhouse
gases” can absorb the heat radiated from the earth (i.e.
Long wave radiation or infrared).
• The greenhouse gases prevent the heat radiated from
the earth from being escaped into space.

8. evidence of global climatic change
 Comes from core samples taken from ocean floor
sediments and ice from Greenland
 ocean sediment contains the remains of calcium
carbonate shells of organisms that once lived near the
surface >>…. indicate the surface water temperature
 the oxygen-isotope* ratio of these shells provides
information about the sequence of glacier advances

9. Continued…..
 study of annual growth rings of trees, called
dendrochronology
 Tree rings are only useful in regions that experience
an annual cycle and in trees that are stressed by
temperature or moisture during their growing season
>>…… correlated with precipitation &
temperature patterns for hundreds of years
past

10. Datas used to reconstruct past climates
 1. records of natural lake-bottom sediment and soil deposits
 2. the study of pollen in deep ice caves, soil deposits, and sea
sediments
 3. certain geologic evidence (ancient coal beds, sand dunes, and
fossils) and the change in the water level of closed-basin lakes
 4. documents concerning droughts, floods, and crop yields
 5. the study of oxygen-isotope ratios of corals and calcium
carbonate stones that grow in the inner ears of fish
 6. the dating of calcium carbonate layers of stalactites in caves

11. How Glaciers Reflect Climate Change
 most valuable proxy tools in which to study climate
change
 they can range in age from hundreds to several
thousands of years old
 Analysis of the oxygen content reveals what the
composition of atmosphere was like at the time that
layer of snow fell on the glacier

12. Continued…..
 Analyzing the 18O/16O ratio reveals the temperature
 Vegetation & other debris trapped in ice that was
carried along with glacier ::;;--- used to unlock past
climate
 Dust reveals ::--- the wind conditions, salt content::--
- evidence of windiness near oceans, & sulphuric acid
content ::--- information about nearby volcanic
activity

13.  glaciers are dynamic & responsive to temperature
change that they are good indicators today of
temperature changes occurring worldwide in the face
of global warming

14. some of the world’s glaciers
 Peruvian Andes, Qori Kalis Glacier is losing as much
ice in one week as it used to lose during an entire
year
 Alaskan glaciers losing an average of 1.8 m of
thickness each year
 glaciers in the European Alps are expected to be gone
by end of the 21st century
 Mount Kilimanjaro’s glacier in Africa is expected to
be gone in about a decade.

15.  glaciers that supply drinking water to northern India
& western China will no longer be able to provide
this life-sustaining service in just a few years
 The glaciers in Canada’s and Montana’s Glacier
National Park will all be melted in the next few
decades

16.  If the snow and ice begin melting in the Arctic, they
will no longer be able to reflect incoming sunlight,
causing the planet eventually to heat up
 The Arctic can also cause a rapid global warming if
the frozen peat bogs begin thawing and large
amounts of CO2 are released into the atmosphere
 most obvious pieces of evidence that climatologists
 have keyed in is the multitude of shrinking glaciers
over the past 50 years

18. Impacts of Glacial Retreat
 The effects will involve drinking water and irrigation
resources—something that everyone in the world
depends on
 the generation of electrical energy,
 the health of habitats connected to glacial regions,
 the presence and use of biochemical elements (long-
lasting pollutants transported by air & deposited on
the glacial ice, & stored or, locked in the ice)
 flooding
 resulting sea-level rise
 effect on the environment

19. The Role of Oceans in Climate Change
 oceans and atmosphere are closely linked to each
other and form the most dynamic part of the climate
system
 Fluctuations in ocean have the ability to magnify,
modify, or minimize atmospheric fluctuations
 small change in one property of the ocean’s
characteristics (transportation, temperature,
upwelling, currents) can result in major
climate changes over large regions of Earth’s surface

20.  Oceans have such immense thermal capacity, it
allows them to slow the rate of climate change
 oceans store & transport CO2
 oceans have absorbed about half of the total CO2
added to atmosphere during last 100 years by
human activities such as the burning of fossil fuels
& deforestation

21.  “sequestering” of carbon is a slow process,
 will not keep up with current rates of CO2 input into
the atmosphere
 Phytoplankton in the ocean also stores CO2 from the
upper layers of the ocean in their carbonate shells
 Eventually, this CO2 settles to ocean floor & gets
buried in the sediment there

22. ocean and atmosphere interact is chemically
 When water evaporates from ocean’s surface, clouds
formed
 Water vapor has a twofold effect:
1) water vapor is a greenhouse gas::--- plays a role in
heating the atmosphere,
2) also forms clouds, which block incoming solar
radiation, thereby cooling Earth
 Over an extended period of time>>---not known if
the net effect from water vapor on global
temperatures will be cooling/ heating

23. ocean’s role with CO2
 most of the world’s carbon is located in the ocean
 exchanges that happen between the upper and lower
levels of the ocean, as well as the ocean surface
&atmosphere, are very important
 Natural chemistry processes play a large part in what
happens to some of this carbon, but biological
processes also play a factor, and they are important
to climate change

24.  The process of photosynthesis turns CO2 into
organic material. When it is in the ocean, it sinks to
the ocean floor>>> CO2 sink
 If ocean’s circulation patterns were disrupted, this
carbon could be released back into atmosphere,
making the oceans a CO2 source instead of a sink

25. Indicators of climate change
 High solar radiation intensities and global warming
 Elevated air temperatures
 Reduced rainfall amounts and occurrence of
droughts
 Unreliable and erratic rainfall events
 Poor rainfall distribution
 Extreme climate events – floods and storms
 Hurricanes and tornadoes

26. Sea-Level Rise
 Rising sea level has the potential to have a negative
impact on human survival, environmental health,
and economics, hence the lifestyle of millions of
people worldwide
 As the atmosphere has warmed in recent decades
and glaciers and ice caps have melted, it has directly
affected ocean levels

27. Sea-Level Rise- result of several processes
 the melting of glaciers & ice caps from continents
(melting of ice already in the water does not affect
sea level)
 thermal expansion of oceans’ upper layers
 melting of the Antarctic & Greenland Ice Sheets
 redistribution of terrestrial water storage
 oceanographic factors, such as changes in ocean
circulation or atmospheric pressure
 vertical land movement

28.  sea-level measurements can be obtained globally
from satellite data
 There are several factors that can cause
variations in sea-level rise,
 the rebound (or rising up) of Earth’s crust after the
melting of ice from the last ice age
 plate tectonics and volcanism raising the height of
the land’s surface
 local subsidence of Earth’s crust from groundwater
extraction
 ground subsidence from sediment compaction
 changes in atmospheric wind patterns and ocean
currents

30. Effects of Sea-Level Rise
 storm surges will increase in intensity, destroying
land further inland from the coastal regions
 Flooding
 freshwater areas will become contaminated with salt
water
 Wildlife that depends on freshwater will have its
habitat negatively impacted
 leave many people homeless and be economically
devastating

31. Marine and Estuarine Water Resources
and Sea Level Rise due to climate change
Effects of sea level rise
 Accelerated coastal erosion. For example, the annual
coastal erosion in the Keta area of Ghana is
estimated to be 3m.
 Inundation of low-lying coastal zones and
 Increased tidal waves which favour further inland
penetration of the sea water through internal lateral
flow, which will increase salinisation of coastal
aquifer and streams.

32. Climate change and Water Resources
Sources of water resources
• natural precipitation
• groundwater resources
• freshwater rivers, streams, rivulets and lakes, dams and
reservoirs and
• marine and estuarine water resources
Natural precipitation is the key source of water that
feeds all the other water resources. Therefore a decrease
in rainfall due to climate change will deleteriously affect
all the other water resources.

33. Climate change and Water Resources
Runoff
• Runoff or overland flow is the major source of water
feeding rives, streams, rivulets, dams, lakes and
reservoirs.
• It is estimated as amount of precipitation minus
infiltration (i.e. the amount of precipitation that
enters the soil).
• The current low levels of water in dams indicate the
sensitivity of reservoirs storage to variations in
runoff due to climate change and drought.

34. Climate change and Water Resources
Groundwater Resource and Climate Change
Groundwater is an important source of global water
requirements for:
• Domestic use
• Agricultural use and
• Industrial use
Groundwater is recharged through:
• Seepage from rainfall events
• Seepage from dams and reservoirs, and
• Seepage from rivers and lakes

35. Marine and Estuarine Water Resources and Sea Level
Rise due to climate change
Climate change and Water Resources
Year Expected sea level
rise (cm)
2020 5.8
2050 16.5
2080 34.5
Table 1. Expected sea level rise in Ghana due to
climate change

36. Abrupt Changes in Climate
 Through the study of ice cores, it has been
determined that abrupt climate changes have
occurred within decades in Earth’s past
 According to the U.S. National Research Council, an
abrupt climate change is when a climate system
changes characteristics into a completely different
mode so quickly that both humans and natural
systems have a hard time adapting to it

37.  Abrupt Changes in Climate include variations of
temperature, precipitation, or extreme weather in a
decade or in just years
 According to the IPCC, human activity today is
affecting climate, but it is difficult to tell the
difference between human-induced changes and
natural changes

38. Climate change and its impact on agricultural
productivity
Stresses due to these two climatic variables result in
reduced crop yields because of the following reasons:
• The plant tries to complete its life cycle more rapidly
resulting in reduced storage of food product.
• Heat stress and reduced water availability could
result in the death of the plant.
• Extreme climatic events such as storms and windiness
can be devastating to plants through logging and
flooding.

39. There are different types of scenarios for the analysis of
impacts of climate change on Agriculture. But the
commonest ones are:
• Global circulation models (GCMs)
• Regional climate (Simulation) Models
(Reg CMs)
Analysis of Climate Change Impacts on
Agriculture

40. Climate Change Impacts in the
Built Environment
 The built environment is
distinctive
 High building mass
increases thermal capacity
 Surface sealing increases
rainfall run-off
 Climate change
strengthens the urban
heat island and
accelerates run-off

41. Change in mean annual temperature by
the end of this century
Based on IPCC
SRES Scenario
A2
(EC Green Paper,
2007)

42. Change in mean annual precipitation
by the end of this century
Based on
IPCC SRES
Scenario A2
(EC Green
Paper, 2007)

43. Studying climate change: Direct sampling
 Scientists have recorded
carbon dioxide levels in
the atmosphere directly
since 1958, at a station in
Hawaii.
 The data show a steady
upward climb from 315 to
373 ppm.
 (The up and down zigzags
are from regular winter-
summer fluctuations.)

44. Studying climate change: Modeling
 To predict what will happen to climate in the future,
scientists use climate models:
 Computer simulations that use known behavior of
past climate to analyze how climate should behave
as variables are changed
 Coupled general circulation models (CGCMs) are
models that combine, or couple, the effects of both
atmosphere and ocean.

45. Studying climate change: Modeling
Today’s highly
complex CGCMs
incorporate many
factors in order to
predict future climate
changes.

46. Climate change and the IPCC report
First, the IPCC report established that global
temperature is rising.
Direct measurements from thermometers since 1860
demonstrate this.

47. Climate change and the IPCC report
Proxy indicators of temperature (from pollen, ice
cores, etc.) were reviewed to establish ancient
temperatures.
These data (BLUE) overlapped with the direct
temperature measurements (RED). (Gray shows
statistical uncertainty.)

48. The IPCC report
The IPCC also reported findings on physical changes:
• Average sea level increased 10–20 centimeters (4–8 inches)
during 20th century.
• 2 weeks less ice cover on northern lakes and rivers.
• Arctic sea ice thinned 10–40% in recent decades.
• Mountain glaciers melted back worldwide.
• Snow cover decreased 10% since satellite observations
began.
• Growing season lengthened 1–4 days each decade over the
past 40 years.

49. Continued…
Biological changes were also found by the IPCC:
• Geographic ranges of many species have shifted toward the
poles and up in elevation.
• In spring, plants are flowering earlier, birds migrating earlier,
animals breeding earlier, and insects emerging earlier.
• Coral reefs are “bleaching” more frequently.

50. Climate change predictions: Impacts
The IPCC and other groups have predicted future
impacts of climate change. Predictions for the U.S.
include:
• Temperature will rise 3–5°C (5–9°F).
• Droughts, floods, snowpack decline, and water shortages will
create diverse problems.
• Temperature extremes will cause health problems; tropical
diseases will move north into the U.S.
• Sea level rise will flood coastal wetlands, real estate.
• Ecosystems will be altered; some will disappear.
• Agriculture and forestry may have mixed results.

51. Factors Leading to potential vulnerability to
climate change
Unsustainable use of natural resources
Lack of mitigation of greenhouse gas
emissions in the industrial sector
Weak waste management systems and
poor environmental sanitation
Imports of over-aged vehicles