Transcript Sustainability4 PowerPoint presentation

Sustainability
and
Globalization
Global Warming
Global Warming
 A global issue with
regards to sustainability
 A world-wide warming
of the Earth’s lower
atmosphere.
Definitions
Climate: The long term average
weather for an area: Months, years,
centuries.
Definitions
Climate: The long term average
weather for an area: Months,
years, centuries.
Weather: the state of
atmospheric conditions over a
short period of time: Hours or
days.
Climate Control
Orbital factors - Milankovitch
Reflectivity of Earth’s surface
(Albedo)
Solar radiation
Volcanic activity
Ocean currents
Atmospheric composition
Climate Control
Orbital factors Milankovitch cycles
Milankovitch cycles
 Amount of heat reaching earth
from the sun varies due to:
1. Eccentricity - 100,000 yrs
Eccentricity
Tilt
W. W. Norton
Precession
Milankovitch cycles
 Amount of heat reaching earth
from the sun varies due to:
1. Eccentricity - 100,000 yrs
2. Earth’s tilt - 41,000 yrs
Eccentricity
Tilt
W. W. Norton
Precession
Milankovitch cycles
 Amount of heat reaching earth
from the sun varies due to:
1. Eccentricity - 100,000 yrs
2. Earth’s tilt - 41,000 yrs
3. Precession - 23,000 yrs
Eccentricity
Tilt
W. W. Norton
Precession
Milankovitch cycles
 Amount of heat reaching earth
from the sun varies due to:
1. Eccentricity - 100,000 yrs
2. Earth’s tilt - 41,000 yrs
3. Precession - 23,000 yrs
 Overall temperature effect +/-
4˚C
W. W. Norton
Climate Control
Orbital factors - Milankovitch
Reflectivity of Earth’s surface
(Albedo)
Reflectivity of Earth’s Surface
(Abedo)
Reflectivity
Sun’s heat may be reflected back
out -thus not absorbed by Earth.
Reflectivity
Sun’s heat may be reflected back
out -thus not absorbed by Earth.
Albedo = the degree of
reflectivity
Reflectivity
Sun’s heat may be reflected back
out -thus not absorbed by Earth.
Albedo = the degree of
reflectivity
Albedo increases with:
 Increased cloud cover
 Increased snow cover
 Increased aerosols in atmosphere
Climate Control
Orbital factors - Milankovitch
Reflectivity of Earth’s surface
(Albedo)
Solar radiation
Solar radiation
Fluctuates with sunspot activity
Increases in sunspots = increased
energy production of sun.
Sunspot cycle is ~9 to 11.5 years
Courtesy of SOHO/MDI consortium. SOHO is a project of
international cooperation between ESA and NASA
Climate Control
Orbital factors - Milankovitch
Reflectivity of Earth’s surface
(Albedo)
Solar radiation
Volcanic Activity
Volcanic Activity
 Sulfur dioxide gas is
ejected into the
stratosphere,
 Combines with water to
form an aerosol (mist) of
sulfuric acid
 Blocks in coming solar
radiation
 Cools Earth
Climate Control
Orbital factors - Milankovitch
Reflectivity of Earth’s surface
(Albedo)
Solar radiation
Volcanic Activity
Ocean currents
Ocean currents
 Important system that moves cold
and warm water.
 Can redistribute heat on earth’s
surface
Climate Control
Milankovitz cycles
Reflectivity of Earth’s surface
(Albedo)
Solar radiation
Volcanic activity
Ocean currents
Atmospheric composition
Atmospheric composition
Greenhouse gases
 Carbon dioxide, methane, CFCs, water
vapor
Atmospheric composition
Greenhouse gases
 Carbon dioxide, methane, CFCs, water
vapor
Earth has a natural Greenhouse
Effect
 Warmer than moon
Atmospheric composition
Greenhouse gases
 Carbon dioxide, methane, CFCs, water
vapor
Earth has a Greenhouse Effect
 Warmer than moon
 Past record shows correlation
between composition and
temperatures.
Why does CO2 Matter?
Greenhouse Effect:
Naturally occurs
CO2 holds Earth’s heat in
The greenhouse effect
 The Sun radiates UV energy towards Earth.
 One third of that Ultraviolet energy is simply reflected
away from the Earth.
 But the rest is absorbed by the Earth.
 In response, the Earth radiates IR energy.
 This Infrared energy is also known as heat.
The greenhouse effect
 Gas molecules in the Earth’s atmosphere absorb the
heat (IR energy) that the Earth radiates.
 These gases are known as “greenhouse gases”.
 The gases then re-emit the IR energy back down
towards the Earth, warming the atmosphere.
Why does CO2 Matter?
Greenhouse Effect:
Naturally occurs
CO2 holds Earth’s heat in
Amount of CO2 in atmosphere
has increased over past 150
years
Where does CO2 come from?
 Short term carbon cycling occurs between plants,
animals and the atmosphere through respiration.
 Long term cycling occurs when the plant or animal
remains are buried with sediments in the crust and
cannot decay.
Where does CO2 come from?
 Long term cycling occurs when the plant or animal
remains are buried with sediments in the crust and
cannot decay.
 Some of these remains become fossil fuels:
 Coal, oil, gas
Where does CO2 come from?
 Burning carbon-based fuel (fossil fuels)
produces Carbon Dioxide (CO2)
fossil fuel + O2 = Heat energy + H2O + CO2
Carbon-based fuels (fossil fuels)
 Provide > 40% world’s energy needs
 Provides 90% of world’s transportation needs.
 Also used to make: plastic, paint, nylon, synthetic
rubber, fertilizer.
How do we know the CO2 comes
from humans burning fossils fuels?
 Climate models
 Scientists use what we know about the controls on
climate to reproduce the record of past
temperatures.
 Then look at which controls influence it the most.
Record of past temperatures
Results of Climate Models for
last 1000 yrs

Solar and volcanic forcing have been
responsible for some of the variations
in Northern Hemisphere temperature
over the past 1000 years.
Results of Climate Models for
last 1000 yrs
 Neither solar nor volcanic influence
can explain the dramatic warming of
the late 20th century.
 Influences of solar or volcanic effects
during the 20th century would
actually have resulted in a small
cooling since 1960.
Results of Climate Models for
last 1000 yrs

Only by adding the human-caused
increase in greenhouse gas
concentrations are the models able to
explain the unprecedented warmth of
the late 20th century.
IPCC:
Intergovernmental
Panel on
Climate
Change
Results of Climate Models for
last 1000 yrs
 The rate of increase of CO2 into the
atmosphere has been very fast, and the
natural cycles have not kept up with it.
Climate Models
Which factor is causing current
increase in global temperature?
 NOAA Paleoclimate group:
 http://www.ncdc.noaa.gov/paleo/globalwarming/mod
eling.html
 Climate Models