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