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GLOBAL CLIMATE CHANGE
GLOBAL CLIMATE ISSUES

Earth-Based Climate Change
◦ Milankovitch Cycles
◦ Volcanic Eruptions
◦ ENSO

Anthropogenic Climate Change
◦
◦
◦
◦
Acid Rain
Greenhouse Effect
Global Warming
Ozone Depletion
MILANKOVITCH CYCLES
Earth’s spin wobbles
 Earth’s elliptical orbit lengthens &
shortens every 100,000 years
 Earth’s angle of tilt fluctuates & wobbles
over a 26,000 year period
 Shift exposes different latitudes to
different amounts of sunlight
 May be responsible for shifts in climate
over the centuries

VOLCANIC ERUPTIONS

Particulate matter from volcanoes blocks
sun’s rays and can cause a drop in global
temperatures
AEROSOL EFFECT

Particulate matter (aerosols) block sun’s
rays & cool Earth
EL NINO/SOUTHERN
OSCILLAION (ENSO)
El Niño describes abnormal oceanic and
atmospheric conditions.
 When the Trade Winds falter, warm water
piles up in the western Pacific about 1 &
½ feet higher than the average ocean
surface
 ENSO cycles are periodic, occurring
every 2-8 years

NORMAL
Normally, trade winds blow warm surface water toward the
western Pacific.
This causes upwelling in the eastern Pacific.
8
EL
NIÑO
10
RESULTS OF ENSO
Warm water & moisture brought to
South America
 Cooler jet stream brings rains to Central
& North America
 More ppt in western US & Gulf region
 Normally moist areas in Australia,
Indonesia, Southeast experience drought,
crop failure & fires

ENSO
Tree ring, ice cap and coral reef data
indicate events becoming more frequent
 La Nina when an El Nino not taking place
 Oscillation between two called El Nino
Southern Oscillation (ENSO)

ACID RAIN
Leaches metals (mercury & cadmium) toxic
to aquatic species & plants
 Changes pH which can change species
present
 Leaches nutrients from soils
 Damage to cells
 Increases nitrates & nitrite nutrients
 Damaged plants more susceptible to
pathogens & insects synergistically (more
pathogens & pests spread to other
organisms easier)

Sources of acid deposition

Originates from burning fossil fuels that
release sulfur dioxide and nitrogen oxides
◦ These compounds react with water to form
sulfuric and nitric acids
Effects of acid deposition
Nutrients are leached from
topsoil
 Soil chemistry is changed
 Metal ions (aluminum, zinc,
etc.) are converted into
soluble forms that pollute
water
 Widespread tree mortality
 Affects surface water and
kills fish
 Damages agricultural crops
 Erodes stone buildings,
corrodes cars, erases
writing on tombstones

pH of precipitation in the U.S.
Many regions of acidification are downwind of major
sources of pollution
GREENHOUSE EFFECT
1/3 of solar radiation is reflected back to
space
 Absorbed radiation is converted to lowenergy long wavelength EMR
 Under normal conditions long-wavelength
EMR emitted back to space
 Certain molecules in the air absorb the
radiation and convert it to heat

THE GREENHOUSE EFFECT
THE GREENHOUSE EFFECT
Absorb infrared radiation
 H2O, CO2, CH4,CFCs, NOx

◦ CO2 largest culprit
 From burning fossil fuels
Carbon dioxide is of primary
concern

Not the most potent
greenhouse gas (GHG), but it
is extremely abundant
◦ The major contributor to
global warming

Human activities have
boosted atmospheric
concentrations from 280
parts per million (ppm) to
383 ppm
◦ To their highest levels in more
than 650,000 years
Other greenhouse gases add to
warming
Methane = fossil fuel deposits, livestock, landfills,
and crops such as rice
 Nitrous oxide = feedlots, chemical manufacturing
plants, auto emissions, and synthetic nitrogen
fertilizers
 Ozone = risen due to photochemical smog
 Halocarbon gases (CFCs) = are declining due to
the Montreal Protocol
 Water vapor = the most abundant greenhouse
gas and contributes most to the greenhouse
effect

◦ Could increase cloudiness, which might slow global
warming by reflecting more solar radiation back into
space
U.S. emissions of major greenhouse
gases
Electricity generation
A coal-fired, electricitygenerating power
plant


Largest source of U.S. CO2 emissions
Two ways to reduce fossil fuel use: conservation and
efficiency
◦ Arise from technology and individual choices
◦ Replacing worn-down appliances with newer models,
lifestyle choices
◦ Use fewer greenhouse-gas-producing products
Transportation
2nd largest U.S. greenhouse gas source
 The typical automobile is highly inefficient
 Ways to help:

◦ Technology: make vehicles more fuel-efficient,
hybrid cars
◦ Drive less and use public transportation
◦ Public transportation is the most effective way to
conserve energy, reduce pollution
◦ Live nearer your workplace, so you can bike or
walk
What causes levels of CO2 to increase?

Burned fossil fuels in our homes, factories,
and automobiles
◦ Transfers large amounts of carbon dioxide from
lithospheric reservoirs into the atmosphere
 main reason atmospheric carbon dioxide
concentrations have increased so dramatically

Deforestation has contributed to rising
atmospheric CO2 concentration
◦ Forests serve as sinks for recently active carbon
◦ Their removal reduces the biosphere’s ability to
absorb carbon dioxide from the atmosphere
Conventional cars are inefficient
Efficiency of Some Common Devices
Device Efficiency (%)








Dry-cell flashlight battery
Home gas furnace
Storage battery
Home oil furnace
Small electric motor
Steam power plant
Diesel engine
High-intensity lamp
 Automobile engine
 Fluorescent lamp
 Incandescent lamp
90
85
70
65
62
38
38
32
25
22
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GLOBAL WARMING

An increase in Earth’s average surface
temperature
GLOBAL WARMING

An increase in Earth’s average surface temperature
Direct atmospheric sampling tells us about the present
Trends in atmospheric
concentrations of carbon
dioxide show that
concentrations have
increased from 315 ppm
in 1955 to 383 ppm in
2010
EFFECTS OF GLOBAL WARMING

Melting Arctic & Antarctic ice caps
◦ Increases sea levels & methane
◦ Flood major population centers

Alpine glaciers melting
◦ Decreased freshwater
Spread of disease-carrying vectors
 Alteration of major biotic factors

◦ Organisms may not be able to survive
EFFECTS OF GLOBAL WARMING
Bleaching of coral reefs
 Melting of permafrost in tundra biomes

◦ Damage structures
◦ Release methane
Release of CO2 when peat warms
 Oceans evaporate causing more energetic
storms

Models help us understand climate

Coupled general circulation
model (climate models) =
programs that combine what is
known about atmospheric
circulation, ocean circulation,
atmosphere-ocean interactions,
and feedback mechanisms to
simulate climate processes
◦ These models are becoming
more reliable in predicting
climate change
KOYOTO PROTOCOL
The Kyoto Protocol is an international
agreement linked to the United Nations
Framework Convention on Climate Change
(FCCC), which commits its Parties by
setting internationally binding emission
reduction targets.
 The Kyoto Protocol was adopted in Kyoto,
Japan, on 11 December 1997


This treaty took effect in 2005, after Russia became
the 127th nation to ratify it
The Kyoto Protocol seeks to limit
emissions
The Kyoto Protocol mandates that, between 2008-2012,
signatory nations must reduce emissions of six GHGs to
levels below those of 1990
 Parties committed to reduce GHG emissions by at least
18 percent below 1990 levels in the eight-year period
from 2013 to 2020
 192 parties have ratified the protocol. The Untied States
has not; it dropped out in 2001.

◦ The United States will not ratify the Kyoto Protocol because it
requires industrialized nations to reduce emissions, but it does
not require the same of rapidly industrializing nations such as
China and India

Businesses in industrialized nations feel they have more
to lose economically from restrictions
Carbon offsets are in vogue


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Emissions trading programs allow participants who cannot
or will not reduce their emissions to use carbon offsets
instead
Carbon offset = a voluntary payment to another entity
intended to enable that entity to reduce the greenhouse
emissions that one is unable or unwilling to reduce oneself
◦ Becoming popular among utilities, businesses, universities,
governments, and individuals trying to achieve carbonneutrality, where no net carbon is emitted
Carbon offsets fall short
◦ A lack of oversight to make sure that the offset money
accomplishes what it is intended for
IPCC

Intergovernmental Panel on Climate Change
◦ Assesses the scientific, technical and socio-economic
information relevant for the understanding of the risk
of human-induced climate change
OZONE DEPLETION
First reported in 1985
 Ozone provides a shield from UV
radiation
 Ice crystals in Antarctic bring CFCs and
O3 together
 Most likely culprit CFCs

◦ CFCs are persistent catalysts and are not
used up in the reaction
Synthetic chemicals deplete
stratospheric ozone

Ozone layer = ozone in the lower
stratosphere
◦ 12 ppm concentrations effectively block
incoming damaging ultraviolet radiation

Chlorofluorocarbons (CFCs) =
chemicals that attack ozone
◦ 1 million metric tons/year were produced
◦ Releases chlorine atoms that split ozone
The hole in the ozone

Ozone hole = ozone levels over Antarctica
had declined by 40-60%
◦ Depletion also in the Arctic and globally
◦ Causes skin cancer, harms crops and decreases
ocean productivity
The Montreal Protocol addressed
ozone depletion


Montreal Protocol = 180 nations agreed to cut CFC
production in half
◦ Follow-up agreements deepened cuts, advanced timetables
and addresses other ozone-depleting chemicals
◦ Today, production and use of ozone-depleting chemicals
has decreased 95%
◦ The ozone layer is beginning to recover
Challenges still face us
◦ CFCs will remain in the stratosphere for a long time
◦ Nations can ask for exemptions to the ban
The Montreal Protocol is a success

Considered the biggest environmental success
story
◦ Policymakers included industry in helping solve the
problem
◦ Implementation of the plan allowed an adaptive
management strategy that changed strategies in
response to new scientific data, technological
advances, and economic figures

The Montreal Protocol can serve as a model
for international environmental cooperation
WEATHER & POLLUTION

Grasshopper Effect – net transfer of
pollutants from milder climates to cooler
climates
◦ Toxins taken up in warmer climates (more soluble)
transported to cooler climates (convection) and
released with or without precipitation (less
soluble in cold)