Date post: | 19-Dec-2015 |
Category: |
Documents |
View: | 214 times |
Download: | 1 times |
Earth : Atmosphere
Lecture 18
2.2 billion years o
ld
Increase in Atmospheric Oxygen
The amount of oxygen in the atmosphere has evolved with time.
Outgassing losing H & He, N2 remain increased O2 & decrease of CO2
Comparing Atmosphere
Structure of Earth Atmosphere Like the interior, the atmosphere has a layered structure.
Layered Structure
Greenhouse effect
Greenhouse effect
Moderate Greenhouse effect is good! Without the modest greenhouse effect
on the Earth, the average global temperature of the Earth would be
-2°F
With the right amount of greenhouse gas, Earth’s average temperature is
58°F
Human and the Earth
A.D.2000
A.D.1000
A.D.1
1000B.C.
2000B.C.
3000B.C.
4000B.C.
5000B.C.
6000B.C.
7000B.C.
1+ million years
8
7
6
5
2
1
4
3
OldStoneAge New Stone Age
BronzeAge
IronAge
MiddleAges
ModernAge
Black Death — The Plague
9
10
11
12
A.D.3000
A.D.4000
A.D.5000
18001900
1950
1975
2000
2100Prediction
Billi
ons
Source: Population Reference Bureau; and United Nations, World Population Projections to 2100 (1998).
World Population Growth Through History
Expo
nenti
al G
row
th
Just how many of us are there?
Paul MacCready, designer of the first solar-powered aircraft, has estimated the total weight of all terrestrial and avian vertebrates.
When agriculture began, we humans and our pets and livestock together accounted for less than 0.1% of the total.
Today, we and our domesticated animals account for 98% of the total
Tokyo Water Park Slogan
“Welcome to breathtaking Tokyo Water Park where you can wash away the pressure and stress of the overcrowded city and relax with your friends in the smoothing enjoyment of sun, fun and splashing."
Summer Beach in Busan, Korea
With its huge and still growing population and rapidly growing per capita use of
resources, China is a disaster not only for China’s own environment, but for the world
as a whole.
• Endless construction of coal burning power plants• Destruction of the world’s rainforests to supply China with food and other
resources• Massacre of 100 million sharks a year for shark’s fin soup• Funding of numerous environmentally and socially destructive dams world-
wide
Just a few specific examples:
Did something change here?
Logarithmic plot straight line in thisplot is exponential behavior
slope indicates growth rate
0.035% per year
1%/yr
A closer look at recent trends…
0.4%/yr
0.8%/yr
1.9%/yr
1865
1950
industrial revolution
green (oil) revolution(pesticides, irrigation, fertilizers…)
Human Impacts on the Earth!
Deforestation : Amazon
Global Warming
Doesn’t everyone already know about Global Warming?
GALLUP annual poll
global warming is generally exaggerated?
392.40 ppm
Venus and Earth
Venus0.7 Astronomical Unit0.95 Rearth
Rocky planetGeological activityThick atmosphere
900°F200,000 more CO2 in atmo
Earth1.0 Astronomical Unit (AU)1.0 Rearth
Rocky planetGeological activityThick atmosphere
57°F
Venus was like a tropical paradise (~80°F) before
Dry effect
Temp was high enough initially so that there was no water condensation
no CO2 dissolutionaccumulated outgassed CO2
warmer tempmore evaporation of waterH2O broken by solar UVhigher CO2 and hotter temp
Wet effect
More net evaporation than precipitation
ocean gradually vanishedhigher T caused rocks to release
stored carbonmore H2O in the atmosphere
causing even stronger greenhouseH2O broken by solar UVdry, barren, hot planet
Either through “Dry” or “Wet” runaway greenhouse effect, Venus lost all her water and CO2 had to be remained in the atmosphere
Can Earth follow the same footsteps of Venus
YES!
“Wet” runaway greenhouse effect on Earth would require that the majority of the oceans around the world would evaporate more water than precipitate critical temperature is about 80F
By 2100, average global temperature can rise ~70F which is dangerously close to the critical point.
The only thing that has prevented Earth from being another Venus was the CO2 cycle which is a slow, yet very delicate process.
If this process were ever to start, there is not way to stop it
Localized Runaway Greenhouse effect Pacific ocean to the NE of Australia exhibited a runaway effect (May 2002)
This location was warm enough year round to continually evaporate more water vapor than precipitated back to it.
Luckily, this is only a localized effect and surrounding ocean compensate for it. But, this may be an example tells us that we are uncomfortably close to the entire planetary runaway effect.
Should we take a risk with the tipping point?
Dr. Martin Luther King, Jr.
"Unlike the plagues of the dark ages or contemporary diseases we do not yet understand, the modern plague of overpopulation is soluble by means we have discovered and with resources we possess. What is lacking is not sufficient knowledge of the solution, but universal consciousness of the gravity of the problem and the education of the billions who are its victims.”
Acceptance Speech: Margaret Sanger Award in Human Rights, 1966
As educated people and citizens, we have responsibilities to remind the public.
In summary…
Important ConceptsEarth’s AtmosphereGreenhouse effect• runaway greenhouse effect
Global warmingSimilarity b/w Venus & Earth
Important TermsRunaway greenhouse effectExponential growth
Chapter/sections covered in this lecture : sections 9-5 through 9-7