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