Case Studies of Important Scientific and Technological Issues

•Nature and Development of Science and Technology

Global Warming Global Warming

IntroductionIntroduction

Greenhouse Effect Greenhouse Effect andand

Composition of the Earth’s Atmosphere

(Gases – Percent by Volume)

Other – 1.4%

Oxygen – 20.6%

Nitrogen – 78%

Argon (0.934%)

Water Vapor (0.4%)

* Carbon Dioxide (0.035%)

Neon (0.00182%)

Hellum (0.000524%)

* Methane (0.00015%)

Krypton (0.000114%)

Hydrogen (0.00005%)

* N2O (0.00003%)

* Ozone (0.000005%)

* CFCS (0.0000001%)

* Known Greenhouse Gas

78% nitrogen

20.6% oxygen

< 1% argon

0.4% water vapor

0.036% carbon dioxide

traces gases:Ne, He, Kr, H, O3 Methane, Nitrous Oxide

Burning of fossil fuelsBurning of fossil fuels

Source: OSTP

DeforestationDeforestation

Source: OSTP

Greenhouse Effect

The Greenhouse Effect

Some solar radiation is reflected by the

Earth and the atmosphere.

SUN

Solar radiation pass through

the clearatmosphere. ATMOSPHERE

EARTH

Some of the infrared radiation passes through the atmosphere,

and some is atmosphere and re-emitted in all directions bygreenhouse gas molecules.

The effect of this is to warm theEarth’s surface and the lower

atmosphere.

Most radiation is absorbed by the Earth’s surface and warms it.

Most radiation is absorbed by the Earth’s surface and warms it.

Infrared radiation isemitted from the

Earth’s surface.

Infrared radiation isemitted from the

Earth’s surface.

Greenhouse Effect & Global Warming

•The “greenhouse effect” & global warming are not the same thing. •Global warming refers to a rise in the temperature of the surface of the earth

•An increase in the concentration of greenhouse gases leads to an increase in the the magnitude of the greenhouse effect. (Called enhanced greenhouse effect) •This results in global warming

Is Global Warming occurring?

Global warmingdoesn’t exist!

Okey, it exists, but it isn’t man-made!

1990 1995

2000 2005OK, so It’s man-made, but it’s effects aren’t all bad

It’s effects will be really bad, but not until after I’m dead.