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Sustainabilityand
Globalization
Global Warming
Global WarmingA global issue with
regards to sustainability
A world-wide warming of the Earth’s lower atmosphere.
DefinitionsClimate: The long term average weather for an area: Months, years, centuries.
DefinitionsClimate: 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 ControlOrbital factors - Milankovitch
Reflectivity of Earth’s surface (Albedo)
Solar radiationVolcanic activityOcean currentsAtmospheric composition
Climate ControlOrbital factors - Milankovitch cycles
Milankovitch cycles Amount of heat reaching
earth from the sun varies due to:
1. Eccentricity - 100,000 yrs
W. W. Norton
Eccentricity
Tilt
Precession
Milankovitch cycles Amount of heat reaching
earth from the sun varies due to:
1. Eccentricity - 100,000 yrs2. Earth’s tilt - 41,000 yrs
W. W. Norton
Eccentricity
Tilt
Precession
Milankovitch cycles Amount of heat reaching
earth from the sun varies due to:
1. Eccentricity - 100,000 yrs2. Earth’s tilt - 41,000 yrs3. Precession - 23,000 yrs
W. W. Norton
Eccentricity
Tilt
Precession
Milankovitch cycles Amount of heat reaching
earth from the sun varies due to:
1. Eccentricity - 100,000 yrs2. Earth’s tilt - 41,000 yrs3. Precession - 23,000 yrs
Overall temperature effect +/-4˚C
W. W. Norton
Climate ControlOrbital factors - Milankovitch
Reflectivity of Earth’s surface (Albedo)
ReflectivitySun’s heat may be reflected back out -thus not absorbed by Earth.
ReflectivitySun’s heat may be reflected back out -thus not absorbed by Earth.
Albedo = the degree of reflectivity
ReflectivitySun’s heat may be reflected back out -thus not absorbed by Earth.
Albedo = the degree of reflectivity
Albedo increases with:Increased cloud coverIncreased snow coverIncreased aerosols in atmosphere
Climate ControlOrbital factors - Milankovitch
Reflectivity of Earth’s surface (Albedo)
Solar radiation
Solar radiationFluctuates 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 ControlOrbital factors - Milankovitch
Reflectivity of Earth’s surface (Albedo)
Solar radiationVolcanic Activity
Volcanic ActivitySulfur 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 ControlOrbital factors - Milankovitch
Reflectivity of Earth’s surface (Albedo)
Solar radiationVolcanic ActivityOcean currents
Ocean currentsImportant system that moves cold and warm water.
Can redistribute heat on earth’s surface
Climate ControlMilankovitz cyclesReflectivity of Earth’s surface (Albedo)
Solar radiationVolcanic activityOcean currentsAtmospheric composition
Atmospheric compositionGreenhouse gases
Carbon dioxide, methane, CFCs, water vapor
Atmospheric compositionGreenhouse gases
Carbon dioxide, methane, CFCs, water vapor
Earth has a natural Greenhouse EffectWarmer than moon
Atmospheric compositionGreenhouse gases
Carbon dioxide, methane, CFCs, water vapor
Earth has a Greenhouse EffectWarmer than moon
Past record shows correlation between composition and temperatures.
Why does CO2 Matter?Greenhouse Effect:
Naturally occursCO2 holds Earth’s heat in
The greenhouse effectThe 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 effectGas 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 occursCO2 holds Earth’s heat inAmount 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 modelsScientists 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
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.
Results of Climate Models for last 1000 yrs
IPCC:
Intergovern-mentalPanel on ClimateChange
The rate of increase of CO2 into the atmosphere has been very fast, and the natural cycles have not kept up with it.
Results of Climate Models for last 1000 yrs
Climate Models
Which factor is causing current increase in global temperature?NOAA Paleoclimate group:
http://www.ncdc.noaa.gov/paleo/globalwarming/modeling.html
Climate Models
