Sustainability and Globalization 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

W. W. Norton Eccentricity Tilt 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

W. W. Norton Eccentricity Tilt 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

W. W. Norton Eccentricity Tilt 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

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

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

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

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 CO 2 Matter? Greenhouse Effect : Naturally occurs CO 2 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 CO 2 Matter? Greenhouse Effect : Naturally occurs CO 2 holds Earth’s heat in Amount of CO 2 in atmosphere has increased over past 150 years

Where does CO 2 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 CO 2 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 CO 2 come from? Burning carbon-based fuel (fossil fuels) produces Carbon Dioxide (CO 2 ) fossil fuel + O 2 = Heat energy + H 2 O + CO 2

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 CO 2 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

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 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- mental Panel on Climate Change

The rate of increase of CO 2 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: eling.html eling.html Climate Models