Green House Gases: An

Introduction

Prepared for Philazine by Philip Woodard – 2008 – all rights reserved ©

Definition• Earth gets energy from the Sun mostly from visible

light • Half of this energy is passed through Earth’s

atmosphere since the atmosphere is transparent to visible light

• Energy that reaches the Earth is absorbed by the surface as heat

• Earth's surface radiates heat energy back out as infrared waves

• Greenhouse gases, not transparent to infrared, trap and absorb earth’s returning infrared radiations

• This delicate system prevents the wild swings in temperature between day and night that planets with no green house gases experience

The Problem is the Balance

• Too many green house gases and the earth warms up– Venus, with lots of CO2 , heats up to 872◦

F

• Too few green house gases and the earth cools off, and day and night temperatures swing more wildly

THE GREENHOUSE GASES

• Water vapor• Carbon Dioxide• Methane• Nitrous Oxide

• NF3

• Ozone• CFC-12• CFC-11

Contributions of Green House Gases

Watervapor

Carbondioxide

Methane

OzoneNOCFCsOthers

Rise in Greenhouse Gases

Man and the Rise of CO2

• The concentration of CO2 in our atmosphere today far exceeds the natural range over the last 650,000 years

• Held steady at 180 to 300 ppm over the last 650,000 years

• By the end of the 21st century, CO2

concentrations will rise to 490 ppm to 1260 ppm (75-350% above the pre-industrial concentration)

Spike in CO2 Since 2000

• Three percent rise in CO2 levels every year since 2000

• China has been responsible for most of this global growth

• Largely from building coal power plants in poorer internal provinces

• The rate of atmospheric CO2 rise is increasing• The rare of increase during the 1960s was

about a third of the rate of increase in the 2000s

Man and the Rise of Methane• The amount of methane in the air has jumped by nearly 28

million tons from June 2006 to October 2007• More than 5.6 billion tons of methane in the air• Methane comes from landfills, natural gas, coal mining,

animal waste, and decaying plants trapped in the Arctic permafrost– Thousands of years ago billions of tons of methane were

created by decaying Arctic plants and frozen in permafrost wetlands and trapped in the ocean floor

• As the Arctic warms, this methane will be freed and worsen warming– Methane is more than 20 times more potent than carbon

dioxide on a per molecule basis in trapping atmospheric heat waves

• Scientists are concerned that what they are seeing could be the start of the release of the Arctic methane

Man and the Rise of NF3

• None in atmosphere naturally• Nitrogen trifluoride has quadrupled in the

last decade and increased 30-fold since 1978

• Used as a cleaning agent in manufacturing liquid crystal displays, computer monitors, and thin-film solar panels

Rises in Greenhouse Gases: 5000

Years

Increase in Some Green House Gases

GasPreindustrial

Level Current Level

Increase since 1750

Carbon Dioxide

280 ppm 384 ppm 104 ppm

Methane 700 ppm 1745 ppm 1045 ppm

Nitrous Oxide

270 ppb 314 ppb 44 ppb

CFC12 -- -- 553 ppt 553 ppt

Where They

Come From

In 2008, a white paper from the Chinese government admitted China’s contributions of green house gases had exceeded those of the United States 10.1

From 1990 to 2007, overall U.S. green house gas emissions have rise by 14.7 percent. the United States 10.2

In the U.S.

Emissions Are Rising

All the Trends Point to a Change

Northern Hemisphere Temps

Population

CO 2 Concentrations

Water Use

Species Extinctions

GDP

Loss of Rain Forest and Woodlands

Paper Consumption

Motor Vehicles

Fisheries Exploitation

Ozone Depletion

Foreign Investment

Longevity of Green House Gases

• Water vapor stays in the atmosphere for days• Other greenhouse gases take many years to

leave the atmosphere– CO2 has an affective lifetime of tens of thousands of

years– Methane has an atmospheric lifetime of 13½ years – Nitrous oxide has an atmospheric lifetime of 120

years– CFC-12 has an atmospheric lifetime of 100 years

Endnotes

10.1 Clifford Coonan, “China Catches up with US in Greenhouse Gas Emissions” Irish Times, November 1, 2008 BACK

10.2 Website, U.S. Environmental Protection Agency, USEPA, August, 2008, USEPA #430-R-08-005 BACK