Download Fundamentals

Fundamentals
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Atmosphere
Climate Variation
Greenhouse Effect
Climate Drivers
Carbon Cycle
Energy Balance
System Inertia
Geologic time
Causes of Climate Change
Earth’s Atmospheric Composition,
Temperatures and Pressure
Composition
Percent
Nitrogen (N2)
78
Oxygen (O2)
21
Argon (Ar)
Carbon Dioxide (CO2)
Water Vapor (H2O)
Sea level Surface Pressure (Bars)
Extreme Surface Temperatures
(°C)
0.93
0.038
0-4
1
60 to −130 (Global Mean = 14.6)
Atmospheric Abundance of CO2
and Global Temperatures
CO2
Percent
Average
Global
Temperature
(°C)
0.018
9
Last Ice Age Maximum
0.028
13
Interglacial Period (Holocene)
0.038
14.6
0.045
16
Critical for Humans and Other Species
0.065
18
Catastrophic for Humans and Other
Species
~0.15
25
Hot House Maximum
96.5
480
Venus Surface
Event
Today
Climate Shift and Temperature
Natural Variations of Climate during Warming
One Way of Causing Short-term Climate Variations
The Greenhouse Effect
changes in the global
average temperature result in
Small
large climate changes
• A 5° C drop in the global average
temperature places us in the depths of an
Ice Age.
• An 8° C rise in the global average
temperature places us near the top of a
Hot House.
Greenhouse Gases and Percent Warming
• Carbon Dioxide - CO2 (56%)
• Methane - CH4 (16%)
• Tropospheric Ozone - O3 (12%)
• Halocarbons (11%)
• Nitrous Oxide - N2O (5%)
Climate Drivers
Change in Temperature with
Height for 2 Amounts of CO2
Continental Absorption of CO2
Energy Balance of the Earth
INERTIA
• General Physics…the resistance to
change in some physical property of a
body or system.
• Global Warming…the resistance to
change in direction of various elements
of the climate system, such as rising
atmospheric CO2, rising temperatures
and melting ice.
Inertia in Action
• CFCs have decreased
dramatically during the
past 20 years.
• The ozone hole in 2006
was as large as ever
because of the long
lifetime of CFCs in the
stratosphere and
continuing emissions.
• It will take about 70
years for the ozone
hole to disappear.
Other Climate Basics
• Feedbacks can cause the climate to
move in one direction or the other
independent of the original cause.
• Abrupt climate changes can drive
the climate very rapidly; up to 8°
C in 10 years or less.
• Uncertainties
Geologic Time
and
Natural Causes of Climate Change
Geologic Timescale
Red and blue areas indicate hot (Hot House) and cold (Ice House) periods
The Geologic Time Scale Relative
to One Year
Absolute Time
Eon or Era
Duration
Percent
(million years) Geologic time
Relative to a year
Starting time
Duration
Precambrian
3,996
88.0
January 1
10 mo. 17 d
Paleozoic
296
6.5
November
18
24 days
Mesozoic
183
4.1
December
12
15 days
Cenozoic
65
1.4
December
26
5 days
Major Human Events Relative to One Year
December 31
Years
before
present
Starting time
Duration*
Human development begins
~7 million
10:30 a.m.
13 hr., 30 min.
Homo species begins
2.3 million
7:34 p.m.
4 hr., 26 min.
Early Homo Sapiens
400,000
11:14 p.m.
46 min.
Homo Sapiens Sapiens (us)
125,000
11:46 p.m.
14 min.
12,000
11:58:21 p.m.
1 min., 21 sec.
Bonze Age begins
5000
11:59:34 p.m.
35 sec.
Early writing
4000
11:59:32 p.m.
28 sec.
250
11:59:58.3 p.m.
1.7 sec.
Average human lifetime
75
11:59:59.4 p.m.
0.6 sec.
Current rapid climate warming
25
11:59:59.9 p.m.
0.1 sec.
Major Event
Civilization begins (Agriculture)
Industrial Revolution (technology)
*Starting time to the present.
The Anthopocene Epoch
• The Anthopocene is a new Epoch
characterized by human-caused
major global changes that have
altered the Earth in fundamental
ways.
• It starts near the beginning of the
Industrial Revolution in 1751.
• We are no longer in the Holocene.
Some Major Changes to Earth by Humans
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Changed Carbon Cycle
Climate Change
Ocean Acidification
Urbanization and Habitat
Encroachment
• Deforestation
• Major Depletion of Marine Food Fish
• Major Disruption of Land Surfaces
Beginning of the Anthropocene
• The diagram shows
some of the criteria
that defines the
Anthropocene.
• The effects of these
changes will leave a
distinct
stratigraphic
marker.
Mass Extinctions
• The K/T extinction was
probably due to a large
impact that radically
changed the climate.
• The other extinctions
appear to be due to
natural climate changes.
• The greatest mass
extinction (P/T) was due
to a climate change from
an Ice House to a Hot
House.
Causes of Climate Change
• Abundance of Greenhouse Gases
• Major Volcanic Eruptions
• Large Asteroid or Comet Impact
• Change in Sun’s Irradiance
• Change in Ocean Circulation
• Continental Drift
• Change in Earth’s Motions
Red = main cause of current global warming
Past Oxygen and CO2
Abundances
Major Volcanic Eruptions
• Large volcanic eruptions can cool
the climate for a few years by
injecting ash into the stratosphere
to reflect the Sun’s radiation back
to space.
• Enormous eruptions over long
periods can emit large amounts of
CO2 to warm the climate.
Mt. Pinatubo eruption lowered the global average temperature between
0.2 and 0.6° C from mid-June 1991 and about 1995
Large Asteroid or Comet Impacts
• Large impacts cool the climate by
injecting dust into the stratosphere
to reflect sunlight back to space.
• If the impact is in limestone a large
impact will first cool the climate
and then heat it up by releasing
large amount of CO2 from the
limestone.
Changes in the Ocean’s Thermohaline
Circulation Can Change the Climate
Continental Drift due to Plate Tectonics can
Change Climate over Millions of Years
Changes in Earth’s Motions can Change the Climate
Variations in the Earth’s Insolation with Time
Changes in the Sun’s Irradiance
Soar irradiance through September 2008.
Reference: Fröhlich, C. and J. Lean, Astron.
Astrophys. Rev., 12, pp. 273--320, 2004. http://www.pmodwrc.ch/pmod.php?topic=tsi/composite/SolarConstant
Solar Irradiance Does Not Correlate with
Human-caused Temperature Increase
Measurements of Surface Temperature and Sun’s Energy
Solar Irradiance, Temperature,
and Atmospheric CO2
Solar Irradiance, Temperature, and
Human-Caused CO2 Emissions
Conclusions
• Only two causes can operate on time scales short
enough to account for today’s rapid warming: 1)
increase in solar irradiance, or 2) increase in
greenhouse gases.
• The increase in solar irradiance is not enough to
account for the present warming, and does not
correlate with its rapid rise.
• The increase in greenhouse gases must be the
primary cause of global warming.
• This is consistent with the observed rapid rise in
both greenhouse gases and their emission by
human activities.