Download Components of the Climate System and the Greenhouse

Component of the climate System and
greenhouse effect
Ladislaus Chang a
Institute of Resource Assessment
Tanzania Meteorological Agency
Education Program on Climate Change and Biodiversity
Conservation, Institute of Resource Assessment, University of Dar
es Salaam,
19 July, 2010 - 3rd September 2010
OUTLINE
1.  Weather and Climate
2.  Components of the climate system
3.  Characteristics of the climate system
4.  The greenhouse effect
Questions to think about
•  What is climate?
•  How is climate different from weather?
•  What controls the climate?
•  Which are greenhouse gases?
•  The role of greenhouse gas in climate
change
Weather vs. Climate
•  Weather variables:
–  Temperature
–  Pressure
–  Clouds
–  Dew point
–  Precipitation
–  Wind
–  Visibility
•  Weather describes
current conditions
•  Climate describes longterm synthesis
–  Means
–  Extremes
–  Frequencies
–  Spatial patterns
•  Impacts are also
assessed
The Climate System
•  Global climate is:
–  Driven by solar radiation (Earth s external
heat engine)
–  Composed of diverse, interrelated
components that function as a whole
Components of the Climate
System
Atmosphere
Biosphere
- Vegetation
- Anthrosphere
Lisosphere
- land
Cryosphere
-ice
Hydrosphere
-ocean
Climate System
Fig. 1.1 Bigg
The role of the climate system
Atmosphere: Volatile turbulent fluid, strong winds,
Chaotic weather, clouds, water vapor feedback
Transports heat, moisture, materials etc. Heat
capacity equivalent to 3.2 m of ocean
Ocean: 70% of Earth, wet, fluid, high heat capacity
Stores, moves heat, fresh water, gases, chemicals
Adds delay of 10 to 100 years to response time
Land: Small heat capacity, small mass involved (conduction)
Water storage varies: affects sensible vs latent fluxes
Wide variety of features, slopes, vegetation, soils
Mixture of natural and managed
Vital in carbon and water cycles, ecosystems
Ice:
Huge heat capacity, long time scales (conduction)
High albedo: ice-albedo feedback
Fresh water, changes sea level
Antarctica 65 m (WAIS 4-6m), Greenland 7m,
other glaciers 0.35m
The role of the atmosphere in energy
v The atmosphere is the most volatile component of
climate system
v Winds in jet streams exceed 100 mph or even 200
mph; winds move energy around.
v Thin envelope around planet 90% within 10 miles of
surface 1/400th of the radius of Earth; clouds
appear to hug the surface from space.
v The atmosphere does not have much heat capacity
v  Weather occurs in troposphere (lowest part)
v Weather systems: cyclones, anticyclones, tropical
storms/hurricanes move heat around: mostly
upwards and polewards
Role of Oceans
v  The oceans cover 70.8% of the Earth s surface.
v  The oceans are wet: water vapor from the surface
provides source for rainfall and thus latent heat
energy to the atmosphere.
v  The heat capacity of the atmosphere is equivalent to
that of 3.5 m of ocean. The oceans slowly adjust to
climate changes and can sequester heat for years.
v  The ocean is well mixed to about 20 m depth in
summer and over 100 m in winter. An overall average
of 90 m would delay climate response by 6 years.
v  Estimate of delay overall is 10 to 100 years.
v  The ocean currents redistribute heat, fresh water,
and dissolved chemicals around the globe.
Role of Land
Ø Heat capacity of land is much less than water:
Ø Specific heat of land 4½ less than sea water
Ø Land plays lesser role than oceans in storing heat.
Consequently:
Ø  Surface air temperature changes over land are large and occur much
faster than over the oceans.
Ø Land has enormous variety of features: topography,
soils, vegetation, slopes, water capacity.
Ø Changes in land and vegetation affect climate through
albedo, roughness and evapotranspiration.
The Role of Ice
Major ice sheets, e.g., Antarctica and Greenland. Penetration of heat
occurs primarily through conduction.
Unlike land, ice melts ⇒ changes in sea level on longer time-scales.
Ice volumes: 28,000,000 km3 water is in ice sheets, ice caps and
glaciers.
Most is in the Antarctic ice sheet which, if melted, would increase sea
level by ∼65 m, vs Greenland 7 m and the other glaciers and ice caps
0.35 m.
In Arctic: sea ice ~ 3-4 m thick
Around Antarctic: ~ 1-2 m thick
CLIMATE SYSTEM
HYDROSPHERE
ATMOSPHERE
CRYOSPHERE
L. VICTORIA
BIOSPHERE
Mt. Kilimanjaro
КИЛИМАНДЖАРО (5895 М)
LISOSPHERE
13
The Climate System
Systems Approach
•  Systems
–  Comprised of diverse components that
function as a whole
•  Climate System
–  Flow of energy and mass between
components
–  Change in one component will affect other
components
–  Linked (coupled) interactions
Climate System
•  Example of coupling
– 
– 
– 
– 
– 
– 
– 
– 
Increase seafloor spreading rate (volcanism) geosphere
More CO2 to atmosphere
atmosphere
Warmer climate
Melt ice
cryosphere
Raise sea level
Alters ocean circulation
hydrosphere
Alters distribution of nutrients- productivity
biosphere
Impact on CO2….
atmosphere...
Climate System
•  Interactions:
–  Complex
• Each component works at a different rate
• Feedbacks
–  Complicated
• Nonlinear patterns of variation
Components of the Climate
System
•  Discuss each component in terms of:
–  Response time- how quickly it responds to
inputs
–  Heat capacity- amount of energy that must be
put into the component to cause a change
–  Albedo -reflectivity of incoming short wave
radiation
Biosphere
- Vegetation
- Anthrosphere
Geosphere
- land
Hydrosphere
-ocean
Atmosphere
Cryosphere
-ice
Atmosphere
•  Response time
–  Strong diurnal cycle
–  Fastest response to perturbation- days to months
–  Mixes globally in months to years
•  Heat Capacity
–  Low heat capacity
–  Easily heated and set into motion
–  Strong vertical and horizontal gradients
Atmosphere
•  Albedo
–  Clouds reflect 50-55%
–  Clear skies reflect ~5%
•  Coupled to other systems through
energy and chemical exchanges
–  Evaporation/precipitation
–  Wind stress
–  Trace gas exchange
Hydrosphere
•  Heat Capacity
–  Very high
–  Stores heat and buffers the system against
change
•  Albedo
–  Ocean surface ~8%
Hydrosphere
•  Coupled to other components through
exchange of energy and mass
–  Evaporation/precipitation
–  Trace gas exchange
–  Land/sea boundary defined by sea level
–  Drives chemical reactions (weathering)
–  Necessary for life (photosynthesis)
Cryosphere- Ice
•  Cryosphere includes: continental ice
sheets, mountain glaciers, ice shelves, sea
ice, snow, permafrost
•  Currently 6% of Earth permanently
covered by ice (highly variable)
Cryosphere
•  Antarctic Ice Sheet
(AAIS)
–  60% of world s
fresh water
–  Sea level would rise
73 m if AAIS melted
(7.4 m sea level rise
if Greenland
melted)
Cryosphere
•  Response time- multiple time scales
–  Rapid seasonal variations- annual meltback
–  Observed decadal changes
–  Ice sheet growth- 10,000 to 100,000 yrs
–  Ice sheet decay- 1,000 to 10,000 yrs
•  Heat Capacity
–  High- lots of energy required for phase transition
(melting)
Cryosphere
•  Albedo
–  Primary role in climate system = reflectivity
–  Highly reflective
• Old snow ~50%
• Fresh snow 80-90%
Lisosphere
Mt Pinatubo
Erupted June 1991
Philippines
Reduced mean global
surface temperature by
0.5C for ~2 years
Lisosphere
•  Albedo
– 
– 
– 
– 
Dark soil ~10%
Light soil ~30%
Black top~5-10%
Concrete ~20%
•  Major impacts on climate
–  Continentality
–  Topography (atm circulation)
Biosphere
•  Can include people (anthropogenic
effects)
•  Response time
–  Individuals – seasonal or annual
–  Communities- centuries
Biosphere
•  Albedo
–  Forests ~5-10%
–  Meadows and crops ~5-25%
–  Rainforests- lowest albedo on Earth
•  Important contributions to climate
–  Evapotranspiration rates
–  Atmospheric composition
–  Albedo (forest ~10%; soil ~25%)
Properties of a System
•  Feedback loops
–  A particular type of interaction between
components of a system
–  A change in Component 1 elicits a change in
Component 2, which in turn comes back to
affect Component 1
Requires a disturbance/perturbation to initiate
the change
Feedback Loops
•  Positive Feedback Loop
–  Interactions amplify the effects of the
disturbance
•  Negative feedback loop
–  Interactions diminish the effects of the
disturbance
Positive Feedback Loop
(amplifies)
•  Temperature decreases
•  Ice grows
•  Albedo increases
•  Temperature decreases
•  More ice grows…
Negative Feedback Loop
(diminishes)
•  Temperature increases
•  Increased evaporation
•  Increased cloud cover
Negative Feedback Loop
(diminishes)
•  Temperature increases
•  Increased evaporation
•  Increased cloud cover
•  Albedo increases
•  Temperature decreases
•  Less evaporation
•  Fewer clouds
Climate Change
Change
–  Compare climate state at one time to some
time in the past or the future
–  Requires record of past climate or predictions
of future climate
Climate Variability
•  Periodic (seasons, annual)
•  Quasiperiodic (El Niño)
•  Chaotic
GREENHOUSE EFFECT & OZONE DEPLETION
The GREENHOUSE EFFECT, like a real greenhouse (below) is
to allow heat in, but not out. Gases in the atmosphere (CO2,
Methane) naturally trap outgoing LW radiation more
effectively than they do incoming SW radiation. This retains
heat, warming the earth’s atmosphere.
This has, over
geological time, been in
balance. Now, human
activity is increasing
such gases so the
warming effect is
(possibly) beyond recall.
This is the modern
The Earth would be -19°C (-2°F) without atmosphere.
99% of the atmosphere is nitrogen and oxygen
which are transparent to radiation
The Natural Greenhouse Effect: clear sky
O3
8%
Carbon
Dioxide
26%
CH4
N20
6%
Water
Vapor
60%
Clouds also have a greenhouse effect
Kiehl and Trenberth 1997
Greenhouse Gases
•  Carbon dioxide – fossil fuel
combustion.
•  Methane – fossil fuel production,
decomposition of organic
wastes.
•  Nitrous oxide - agricultural and
industrial activities, as well as
during combustion of solid
waste and fossil fuels.
Greenhouse
Gases
•  Greenhouse
gases are
emitted by
human
activities.
Do you know ?
Without green house effect, the global
average temperature on earth would
be
-18°C, whereas at the moment it is
+15°C.
Definitions of 'greenhouse
effect'
•  warming that results when solar radiation is trapped by
the atmosphere: caused by atmospheric gases that allow
sunshine to pass through but absorb heat that is
radiated back from the warmed surface of the earth
•  FACT:- If the greenhouse effect did not exist at all the
earth would be a frozen lifeless planet.
•  FACT:- Carbon dioxide is responsible for about 50% of
the Greenhouse Effect.
•  These gasses are known as greenhouse gasses, and the
main ones are Carbon dioxide Methane and
Chlorofluorocarbons better known as CFC's.
Gases involved in the Greenhouse Effect: past and
present concentration and sources.
Greenhouse Gas
Concentration Concentration
1750
2003
Carbon Dioxide
280 ppm
376 ppm
Methane
0.71 ppm
1.79 ppm
270 ppb
319 ppb
0
880 ppt
Nitrous Oxide
Chlorofluorocarbons
(CFCs)
Natural and
Anthropogenic
Sources
Organic decay;
Forest fires;
Volcanoes;
Burning fossil
34%
fuels;
Deforestation;
Land-use
change
Wetlands;
Organic decay;
Termites;
Natural gas &
oil extraction;
152%
Biomass
burning; Rice
cultivation;
Cattle; Refuse
landfills
Forests;
Grasslands;
Oceans; Soils;
Soil
cultivation;
18%
Fertilizers;
Biomass
burning;
Burning of
fossil fuels
Refrigerators;
Aerosol spray
Not
propellants;
Applicable
Cleaning
solvents
Percent
Change
Questions for group discussion
1.  Which component of the climate system is more affected by
climate change?
2.  Discuss the linkage between the components of the climate
system and from African perspective identify the component
that is more affected by human activities?
3.  Discuss the relationship between climate variability and
climate change. Identify a country or region in Africa where
rainfall is increasing and temperature is decreasing and
explain the reason
4.  Discuss the Greenhouse effect and identify the major sources
of Carbon dioxide and Methane in Africa
Thank You