EARTH’S ATMOSPHERE, PAST AND...
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Transcript of EARTH’S ATMOSPHERE, PAST AND...
EARTH’S ATMOSPHERE,
PAST AND PRESENT
1. Introduction
2. Evolution of Earth’s atmosphere
3. Present-day composition
4. Atmospheric density and pressure
5. Atmospheric structure
6. Air pollution
Earth’s atmosphere: a thin envelope of gases.
Source: Christopherson, 2009, p. 63.
Earth’s atmosphere: a thin envelope of gases.
Source: Weber State University HARBOR balloon flight, August 2009.
Age
(bn. yrs BP)
Composition Features
4.6 to 4.0 H2O, HCN, NH3,
CH4, S, Cl, others
Primary atmosphere, lost to
space
4.0 to 3.3 At 4.0: H2O, CO2,
N2, S, hydrocarbons,
little/no free O2
Outgassing; anaerobic.
At 3.6: chemosynthetic
bacteria
3.3 to 0.6 At 3.0: CO2, H2O,
N2, <1% O2
Outgassing
At 3.3: first photosynthesis
in cyanobacteria
0.6 to present Today: 78% N2, 21%
O2, 0.9% Ar, 0.036%
CO2, trace gases
Gradual development of
atmosphere; abundance of
LIFE
EVOLUTION OF EARTH’S ATMOSPHERE
(Source: After Christopherson, 1997)
The GAIA hypothesis, formulated by
Jim Lovelock in the 1970s and early ’80s
Basic concepts:
• The Earth is ‘alive’, that is, functions as
one enormous organism
• Consequently, the Earth’s biosphere helps
regulate conditions to keep conditions
suitable for itself
Formation of Earth
and the solar system Present day
The Faint Young Sun Paradox
4 3 2 1 0
Billion years BP
0.8
0.9
1.0
1
10
100
1000
CO2
relative to
present Temp.
(K)
320
230
140
Solar luminosity
relative to present
The ‘faint young sun’ paradox. Source: Frakes, et al., 1992.
Evolution of Earth’s atmosphere over
billions of years shows that
composition is DYNAMIC, not static,
i.e. it can and does change over time.
Components of the Lower Atmosphere (% dry air)
Oxygen
Nitrogen
Others
Oxygen 21
Nitrogen 78
Others 1
Argon 0.93
CO2 0.03
Others 0.04
ATMOSPHERE
BIOSPHERE
LITHOSPHERE
HYDROSPHERE
The ecosystem
concept: biotic
and abiotic
components. Source: Christopherson,
2012, p. 558.
Producers
Consumers
Decomposers
Nutrients
Carbon dioxide cycle. Source: Christopherson, 2012, p. 566.
On time-scales less than billions of years,
atmospheric composition changes less
dramatically, but still changes, especially
concentrations of gases such as carbon
dioxide and methane.
These changes are natural over relatively
longer time-scales (100,000 year cycles), but
recent evidence suggests humans have
affected the composition of Earth’s
atmosphere since the industrial revolution
(roughly 1850).
Atmospheric carbon dioxide concentrations
over the last 1000 years. Source: IPCC, 1996.
Car
bon d
ioxid
e co
nce
ntr
atio
n (
ppm
)
Years before
present
Source: data from WDC Paleoclimatology and NOAA Mauna Loa CO2 records.
Couldn’t this all be part of a natural cycle? Atmospheric CO2 recorded in the Vostok ice core, Antarctica, and
measured at Mauna Loa, Hawaii.
Recent carbon
dioxide
increases in the
context of the
last 1000
years.
Source: Christopherson,
2012, p. 285; Arctic Climate
Impact Assessment, 2004.
Atmospheric carbon dioxide concentration recorded at
Mauna Loa, Hawaii. See Christopherson, 2012, p. 64.
300
310
320
330
340
350
360
370
380
390
400
1958 1968 1978 1988 1998 2008
Atm
os
ph
eri
c c
arb
on
dio
xid
e (
pp
m)
Year
Data source: NOAA Earth Systems Research Laboratory, http://www.esrl.noaa.gov/gmd/ccgg/trends/.
Trends in atmospheric carbon dioxide
concentration over the last 800,000 years.
Source: NOAA Earth Systems Research Laboratory, http://www.esrl.noaa.gov/gmd/ccgg/trends/history.html
Atmospheric methane concentrations. Source: IPCC, 1996.
Global average temperature change over the last 140 years.
Source: IPCC, 2001.
Global average temperature change over the last 140 years.
Source: The heat is on, The Economist, 2011.
Global average temperature change over the last 1000 years. Source: IPCC, 2001.
Recent carbon
dioxide
increases in the
context of the
last 1000
years.
Source: Christopherson,
2012, p. 285; Arctic Climate
Impact Assessment, 2004.
Source: Christopherson,
2012, p. 62.
Height
in miles
Height in
kilometres
Atmospheric
pressure in millibars
Sourc
e: C
hri
stopher
son,
2012, p.6
2.
Height
in miles
Height in
kilometres
Temperature
Troposphere
Stratosphere
Mesosphere
Thermosphere
Sourc
e: C
hri
stopher
son
, 2012, p61.
Normal lapse rate.
Source: Christopherson, 2012,
p. 66.
The atmosphere as
a protective filter.
Source: Christopherson, 2012, p. 66.
Space shuttle Endeavour viewed from the International
Space Station. Source: Eos volume 92 number 50, p. 471, 13 December 2011
Troposphere
Stratosphere
Mesosphere
Smog in the Wasatch Front/Salt Lake City area.
Source: Salt Lake Tribune, 2002.
Smog in the Wasatch
Front/Salt Lake City
area, during and after
an inversion.
Source: Salt Lake Tribune, 2007.
County Grade
Cache C
Weber F
Davis F
Salt Lake F
Utah F
Utah air quality
grades 2007 for
ozone (24-hr).
Source: American Lung Association.
County Grade
Cache F
Weber F
Davis F
Salt Lake F
Utah F
Utah air quality
grades 2007 for
particulates (24-hr).
Source: American Lung Association.
Formation of
photochemical
smog. Source: Christopherson, 2012, p. 74.
Air pollution and mixing in the atmosphere:
the effects of inversions. Source: Christopherson, 2012, p. 72.
Air pollution and mixing in the atmosphere:
the effects of inversions. Source: Christopherson, 2012, p. 72.
Atmospheric concentration of CFC-11. Source: IPCC, 1996.
Source;
Christopherson,
2009, p. 71.
Source; Christopherson, 2012, p. 69.
Antarctic ozone hole as measured
by NASA TOMS instrument.
Antarctic ozone hole, September 12 2008.
Source; Christopherson, 2012, p. 68.