Natural Hazards
Climate and Climate Change
Chapter 12
Learning Objectives

Understand the difference between climate and weather,
and how their variability is related to natural hazards

Know the basic concepts of atmospheric science such as
structure, composition, and dynamics of the atmosphere

Understand how climate has changed during the last
million years, through glacial and interglacial conditions,
and how human activity is altering our current climate
Learning Objectives, cont.

Understand the potential causes of climate change

Know how climate change is related to natural hazards

Know the ways we may mitigate climate change and
associated hazards
Climate and Weather

Weather = short periods of time.

Climate = a long period of time.

Climate zones

Defined using Koeppen System

Uses monthly average temperature and precipitation

What information is provided in a climograph?
Climographs - Annual Temperature and Precipitation
Notice that in the northern hemisphere
June and July are warmest months.
Notice that in the southern hemisphere
June and July are coldest months.
Notice that some places have a DRY season.
The United States exhibits all of the major world climate zones
E = Polar
D = severe
continental
C = mild
B = dry
A = tropical
H = mountains
Koeppen’s Classification
System

A-tropical, temp>18oC (64oF) year round

B-Dry, evaporation > precipitation

C- Mild Mid-latitude, 18oC (64oF)>coldest month> -3oC
(27oF)

D- Severe Mid-latitude, coldest month< -3oC (27oF)

E – Polar, temp < -3oC (27oF) year round

H-Highland, Mountain areas
Allred’s climate zone summary for the United States
E
Polar
B cold
C mild
Marine West Coast
B hot
D
cold-wet
C
warmwet
C mild
A
coastal
Mediterranean
Tropical
H
mountains are mostly in the western
United States
Hawaii also has
tropical “A”
Atmospheric Conditions

Permanent gases

Variable gases
Gases whose proportions
Water is key to
everything else.
CO2 is now
above 400 ppm
Permanent Gases

Nitrogen, oxygen, and argon

About 99% of the atmosphere

Relatively unimportant to atmospheric dynamics
Permanent Gases
Nitrogen in the air is mostly inert. However,
if you put energy into making nitrogen
compounds, you can get that energy back later:
Fertilizer
Rocket fuel
Explosives
Oxygen is largely inert until it ‘oxidizes’ other
elements and compounds, creating powerful,
variable atmospheric gases.
Humans create far more variable gases than
nature needs to maintain earth stability.
Oxygen is also relatively inert as an
atmospheric component.
However, oxidation combines oxygen with
carbon, nitrogen and many other elements to
produce molecules that are complex, reactive
and important.
Are combustion, fire and explosion forms of
oxidation? <Yes.>
Consider the variable gases that result.
Variable Gases – Carbon Dioxide (CO2)

Extremely important, but still only about 400 parts per
million in the air

Released naturally by volcanic activity, plant and animal
respiration, decay of organic material.

Released unnaturally by anthro (human) processes.

Don’t forget the carbon monoxide also results from
combustion and is a genuine poison.
Variable Gases – Carbon Dioxide (CO2),

Anthropogenic (human) sources


Burning of fossil fuels increases CO2 .
Deforestation means that excess CO2 not removed.

Atmospheric levels are increasing by 2 ppm per year.

Soil and oceans may be reaching their limits in how
much CO2 they can absorb.
Let’s look at variable gases – starting with
water vapor

Water processes are a solar energy function

Water vapor is humidity created by evaporation

Storing energy in the atmosphere as vapor is an efficient
way to move energy and provoke vast earth changes and
life processes.
Storing heat as water vapor is also a source of energy for
violent storms.

.
Ice contains
substantial heat
energy.
Liquid water
contains a lot
more heat
Water vapor
contains dangerous
amounts of
latent heat
Variable Gases – Ozone O3

Forms when atomic oxygen (O) collides with oxygen
molecule (O2) – ozone is produced by collision with
incoming ultraviolet solar energy.

Mostly found in stratosphere

Acts as a shield for ultraviolet light and is essential to life
on earth

Chlorofluorocarbons (CFCs) partially destroyed ozone
shield


Increases skin cancer, cataracts, caused local crop failures
Ozone is also created by sunlight interacting with oxides of
nitrogen and sulfur.
True or False?
1. If human activity can reduce the
earth’s ‘ozone layer’ then doing so
should help make the surface of the
earth warmer.
2. A small increase in ocean
temperature represents a vast increase
in energy.
3. A small change in atmospheric gases
can warm the atmosphere and the
ocean beneath.
Consider current Salt Lake area news: The Stericycle company uses high
heat to kill pathogens in medical waste.
Neighbors want the waste management plant shut down.
Questions:
1. Does burning waste contribute to climate-changing greenhouse gases?
<yes>
2. Can the process simply fail at times -- releasing excess air pollution?
<yes>
3. Does high heat reduce halogens (chlorine, fluorine, bromine-based
chemicals), heavy metals and other toxins, such as radio-active isotopes?
<many toxic substances are not destroyed by fire>
4. If Uv and Ozone are dangerous, then can they be used to sterilize food and
kill pathogens?
<yes>
Variable Gases – Methane (CH4)

Primary constituent of natural gas

Occurs naturally from bacterial decay, intestinal tracks of
termites, cows, and sheep

Anthropogenic sources: coal mines, oil wells, leaking
natural gas pipelines, rice cultivation, landfills, and
livestock

Levels have doubled since 1700 and is a significant
contributor to warming

Methane is more than 20 times per unit more powerful
than CO2 as a ‘greenhouse’ gas.
Variable Gases – Oxides of
Nitrogen (N O, NO , NO, etc.)
2
2

Nature makes some oxides of nitrogen through wildfires,
ocean waves and soil building.

Human sources include fertilizers and burning fossil
fuels.

Contributes to atmospheric warming.
N2O is also “laughing gas”
at the dentist’s office and
dragster racing fuel.
Variable Gases – Halocarbons

Chemical compounds containing halogen elements bonded
with carbon

Include CFCs and are almost entirely anthropogenic

Used in industrial processes, fire fighting, and as
fumigants, refrigerants, and propellants

Contribute to warming in troposphere and ozone depletion
in stratosphere

Halocarbons are extremely useful, inexpensive and not
particularly toxic when in appropriate use. Replacements
are less competent and cost more.
Aerosols
(microscopic particles including ice)

Provide surfaces that help water vapor condense back to
liquid – rain/snow may not occur without a place to go.

Associated with air pollution

Natural sources: desert dust, wildfires, sea spray, and
volcanoes

Human sources: burning of forests and fossil fuels

Aerosols can be dense enough to cool the earth by
screening out solar energy.
Aerosols
During a drought “rain makers” might throw dust in the air
to provide ‘condensation nuclei’
How does that process compare to what your car is doing
right now in the parking lot?
On “911” when airliners were grounded, the absence of
vapor contrails allowed the earth to warm-up by about one
degree.
Rain sometimes occurs after bomb blasts toss dust and
smoke into the air.
Montreal Protocol
(banned CFCs – ozone layer is slowly repairing itself)
Kyoto Protocol
(tries to limit CO2 but has not been fully ratified CO2
is still increasing in the atmosphere)
Structure of Atmosphere,
revisited

Defined by changes in air
temperature

Troposphere is where
weather happens

Stratosphere dry, cold
layer


Little weather occurs here
Strong winds circulate
aerosols
Atmospheric Circulation

Responsible for location of climate zones

At equator, warm air rises towards poles

Dry air descends near 30o North and South latitude

Descending air produces high pressure and low rainfall

High pressures at North and South Poles – dry/cold
dense air

Mid-latitude storms are the ‘battleground’ between the
dry heat of deserts to the south and polar deserts to the
north.
Mid-latitudes
host the world’s
most violent
storms and the
most people.
Pleistocene Epoch

Multiple ice ages

Glaciers covered 30% of
Earth (today 10%)

Maximum extent 21,000
years ago

Global sea level >100 m
(330 ft) lower than today
The Greenhouse Effect
Earth’s temperature depends on three things:
1.
Amount of sunlight received – variations in solar flow
2.
Amount of sunlight reflected
3.
Degree to which the atmosphere retains heat
•
•
Water vapor, carbon dioxide, methane, nitrous oxides, and
halocarbons absorb IR radiation
Gases act as “blanket” to retain heat in troposphere
Key factor: mostly shortwave solar energy
gets in easily. Once converted to mostly
long wave energy, it is harder to get back
out. Over-warming happens rather easily.
How solar energy enters the atmosphere and then leaves
See simplified version
next page
We can simplify the earth’s “solar budget”
For each 100 incoming:
31 reflected back out
69 absorbed:
- 45 by land and water
- 21 by the atmosphere
- 3 by the ozone layer
Total for atmosphere = about
24 percent
69 total absorbed
How much leaves quickly by longer-wave
radiation? <69>
The “Greenhouse Effect” is
vital to keep the earth at a
healthy temperature
(average 59°F)
However, human air
emissions appear to be
making the earth too warm:
CO2, CO, CH4, Nox, Sox, O3.
Carbon Dioxide and The
Greenhouse Effect

Carbon dioxide accounts
for most of humancaused greenhouse effect.
Air Temperature and
Carbon Dioxide
Notice that air temperature varies with carbon dioxide in
the atmosphere – more CO2 => more heat
Atmospheric Carbon
Dioxide Concentrations

Burning fossil fuels raises
world CO2 concentration
exponentially.
Human industrial age
Atmospheric Carbon Dioxide
Concentrations, cont.

CO2 levels go down in
summer when plants
absorb it.

CO2 goes up in winter
when plants are dormant
and humans continue to
drive cars and run power
plants.
Global Temperature
Change–Last 140 Years



1750, warming trend begins until 1940s.
1910 to 1998, global temperatures rise.
Temperatures in past 30 years are warmest since monitoring began.
Volcanic Forcing

Ash from eruptions becomes suspended in the
atmosphere, reflects sunlight having a cooling effect.

Mount Tambora, 1815 eruption contributed to cooling in
North America and Europe.

Mount Pinatubo in 1991 counterbalanced global
warming during 1991 and 1992.
Effects of Climate Change
November 11, 2013 New York Times article on
concerns in Miami and environs. High-tide flooding.
Desertification and Drought

Climate change increases human induced conversion of
land to desert

Causes soil and natural vegetation degradation

Long-term loses for agriculture and grazing

Increase in drought events

Wildfires may become more common and more violent
As the
atmosphere
gets warmer
Sea level
should rise.
In a sense, Geography 1700 is not as much about
the earth as it is about how people think,
wherever they are.
Systematic thinking is helped by systematic
visualizing.
Consider two ‘climate change’ problems:
Problem 1. The sequence of
building a thunderstorm.
Problem 2. The sequence of
atmospheric gas interaction.
Problem #1: The Sequence of building a
thunderstorm
Step 1:
The Big Six
Characteristics
of the
Atmosphere
(and sequence)






Air temperature
Air pressure
Wind
Humidity
Cloudiness
Precipitation
Step #2 Storms are a SOLAR Process
Air warms
Warming air expands  pressure
Pressure  wind
Wind and heat  evaporate water
Vapor is latent heat hidden in humidity
Warm vapor is light-weight  rises
Rising air  decompresses
Decompressing air  cools by expansion
Cooling leads to  saturation condensation –
 vapor goes to liquid
Liquid precipitates  rain, snow
With enough heat, the process repeats and builds
Anything that alters the
atmosphere to retain more
heat will lead to more energy
for:
- severe storms
- drought
- rising sea levels
Example #2 – Climate Change is
About Atmospheric Warming
99% Permanent Gases – neutral
(except as plant food)
Humans burn fossil fuel  adds
more oxides of carbon
and oxidizes nitrogen and sulfur
1% Variable Gases include greenhouse’
gases (GHG) that keep the earth warm.
More GHG  more earth warming
More warming  more evaporation
 smog (Nox, Sox)
 more energy for storms
 Sunshine and Nox, Sox  ozone
(more smog)
 bigger deserts
 more heat worsens smog
“Bottom Line”?
Burning fossil fuels
returns vast amounts of
ancient “stored sunshine”
back into the atmosphere,
promoting:
-
More heat
More acidity
Air pollution
Even neutral nitrogen
gets pulled into the
fire and converts to
more acidic oxides
and more ‘smog.’
Sunshine then
combines with smog
oxides to produce
more ozone.
What is the “Ozone” story?
Atmospheric ozone
is made naturally in the
stratosphere by Uv
colliding with oxygen.

That process absorbs 95%
of dangerous Uv.
Man-made CFCs destroy
atmospheric ozone.

Ground-level ozone is
made by natural &
human processes.

Nasty stuff.
Solution: Humans have banned
CFCs, but we still produce vast
quantities of hazardous groundlevel ozone.
Excessive ozone is the #1
reason for Utah air-quality alerts.
Bicycles are the answer.