Transcript Climate Disruption and Ozone Depletion

Climate Disruption
and Ozone Depletion
Chapter 15, Part 2
Weather temperature and precipitation in a given area over a
period of hours or days.
Climate temperature and precipitation over at least 30 years.
Section 15-4
HOW MIGHT THE EARTH’S CLIMATE
CHANGE IN THE FUTURE?
The NATURAL Greenhouse Effect
➢ Major
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factors shaping the earth’s climate:
The sun.
Atmosphere
-Greenhouse effect that warms the earth’s lower
troposphere and surface because of the
presence of greenhouse gases.
-Natural cooling process through water vapor in
the troposphere (heat rises).
Oceans store CO2 and heat, evaporate and
receive water, move stored heat to other parts of
the world.
Past
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3.5 billion years - volcanic emissions,
changes in solar input, continents
moving have altered climate.
900,000 years - glacial (cooling) and
interglacial (warming) periods .
10,000 years – steady interglacial period
1000 years – temp. rise, esp. w/ burning
more fossil fuels.
Past temperature changes are
estimated through:- radioisotopes in rocks
and fossils
- trapped bubbles and other materials in glaciers;
- pollen, tree rings
- temperature measurements since 1861
PAST CLIMATE AND THE
GREENHOUSE EFFECT
Major Greenhouse GASES
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The major greenhouse gases in the lower atmosphere are
water vapor (H2O), carbon dioxide (CO2), methane (CH4),
and nitrous oxide (N2O). Also CFCs (which cause ozone
depletion as well!).
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These gases have always been present in the earth’s troposphere in
varying concentrations.
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Fluctuations in these gases, plus changes in solar output are the
major factors causing the changes in tropospheric temperature over
the past 400,000 years.
Global warming and human actions
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➢ CO2 from human activities. 285 parts per
Ice cores show that CO2 levels
million (ppm) in1850 to 390 ppm in 2010
in the troposphere are the
(37% inc).
highest they have been in
➢ Tipping point @ 450 ppm?
650,000 years.
How CO2 emissions from the burning of fossil fuels in
selected countries increased between 1965 and 2009
The SCIENTIFIC Consensus about
Future Climate Change
The Intergovernmental Panel on Climate Change (IPCC)
established in 1988 to document past climate changes and
project future changes; more than 2,500 climate scientists from
more than 130 countries. Findings:
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1906 and 2005, the average global
surface temperature has risen by
about 0.74 C° (1.3 F°). Primarily
since 1980
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(2000–2009) was the warmest
decade since, and 2010 was the
warmest year on record.
In some parts of the world,
glaciers are melting and floating
sea ice is shrinking.
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FACTORS AFFECTING THE
EARTH’S TEMPERATURE
➢ Some
factors can amplify (positive feedback)
and some can dampen (negative feedback)
projected global warming.
Global warming FEEDBACK
Can lead to
“tipping point”
Positive (more warming)
➢Water absorbs heat, melted ice reflects less sunlight back into space.
➢Accelerated C cycle in soils = more CO2 in atm
➢Warmer oceans hold less dissolved CO2Ocean acidification - dissolves CaCO3 in
shells, corals
➢Drought – more fires – more CO2- ↑warming - ↑drought
➢Warmer temperatures melt permafrost releasing trapped CO2 and CH4.
➢Click for short video on feedback systems
Unpredictable?
➢Aerosol and soot pollutants produced by human activities can warm or cool the
atmosphere.
➢Cloud cover can warm or cool the atmosphere as well.
Negative (less warming)
> Ice caps reflect heat (this is lost with melting)
> Increased CO2 in the troposphere can increase plant photosynthesis (effect slows
as plants mature and CO2 released when plants die).
Section 15-5
WHAT ARE SOME POSSIBLE
EFFECTS OF A WARMER
ATMOSPHERE?
PREDICTIONS
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CO2 remains in the atmosphere for 25-100 years, so
even if we stop emissions completely now, there will be
warming effects for a long time.
A minimum increase in average global temperatures of
2 degrees Celsius is considered inevitable (Hertsgaard,
Hot, 2011, p. 51).
This could be accompanied by a 3 ft rise in sea levels
by 2100 around California (Pacific Institute, from Hot, p.
35). USGS (2008) predicts 3-6.5 feet.
There is little time to deal with harmful effects. Cut
global CO2 emissions in half over the next 50 years.
EFFECTS OF GLOBAL WARMING
➢A
warmer climate would have beneficial and
harmful effects but poor nations in the tropics
would suffer the most.
Impact of oceans rise by 14m on Florida, USA
Source: Google Earth
http://flood.firetree.net/?ll=27.2839,80.7275&z=10&m=14&t=1
EFFECTS: Melting Ice
Satellite data shows a 39% drop in the average cover
of summer arctic sea ice between 1979 and 2010
EFFECTS: Ocean Acidification
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A warmer troposphere can decrease the ability of the ocean
to remove and store CO2 by decreasing the nutrient supply for
phytoplankton and increasing the acidity of ocean water.
➢ The ocean can absorb massive amounts of CO2. Dissolved
CO2 forms carbonic acid in water.
➢ More CO2 = More ocean acidity
➢ This lowers the pH = “Acidification”
➢ Can pose problems for marine organisms
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http://www.nsf.gov/news/special_reports/degree/carbon.jsp
EFFECTS: Rising Sea Levels
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During this century rising seas levels
are projected to flood low-lying urban
areas, coastal estuaries, wetlands,
coral reefs, and barrier islands and
beaches.
If seas levels
rise by 9-88cm
during this
century, most of
the Maldives
islands and their
coral reefs will
be flooded.
150 million
coastal people
could be
displaced
EFFECTS: Changing Ocean Currents
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Global warming could alter ocean currents and cause both
excessive warming and severe cooling. Dense, salty, cool
water in north Atlantic initiates the currents above. Climate
change could bring more fresh water (less dense) to N
Altantic and alter or stop the current.
EFFECTS: Extreme Weather
➢ Global
warming will lead to prolonged heat
waves and droughts in some areas and
prolonged heavy rains and increased flooding
in other areas.
EFFECTS:
Biodiversity Winners and Losers
30% of the land-based plant and
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animal species assessed so far
could disappear if the average
global temperature change exceeds
1.5–2.5º. Especially:
-Plant and animal species in
colder climates
-Species at higher elevations
-Plant and animal species with
limited ranges
-Those with limited tolerance for
temperature change.
-Coral reefs.
-Coastal wetlands.
Possible effects of global
warming on the geographic
range of beech trees
based on ecological
evidence and computer
models.
EFFECTS: Agriculture
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By 2059 up to 45% of the world’s land area could experience
extreme drought.
By 2050, 200–600 million more people could face starvation
and malnutrition
In a warmer world, agricultural productivity may increase in
some areas and decrease in others.
Crop and fish production in some areas could be reduced by
rising sea levels that would flood river deltas.
Global warming will increase deaths from:
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Heat and disruption of food supply.
Spread of tropical diseases to temperate regions.
Increase the number of environmental refugees.
EFFECTS: Health
Microbes that cause infectious tropical diseases such as
dengue fever and yellow fever are likely to expand their ranges
Areas in blue show counties in 28 U.S.
states where one or both species of
mosquitoes that transmit dengue fever
have been found as of 2005
Effects for non-human organisms as
well: The orange-colored trees are those
that are dead or dying—killed by
mountain pine beetles
Section 15-6
WHAT CAN WE DO TO SLOW
PROJECTED CLIMATE CHANGE?
Scientists have come up with this list of
possible climate change tipping points
DEALING WITH GLOBAL WARMING
➢ Climate
change is such a difficult problem to
deal with because:
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The problem is global.
The effects will last a long time.
The problem is a long-term political issue.
The harmful and beneficial impacts of climate
change are not spread evenly.
Many actions that might reduce the threat are
controversial because they can impact
economies and lifestyles.
DEALING WITH GLOBAL WARMING
➢ Two
general ways to deal with global
warming:
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Mitigation that reduces greenhouse gas
emissions: reduce fossil fuel use
Adaptation, where we recognize that some
warming is unavoidable and devise strategies to
reduce its harmful effects: build sea walls
Solutions
Mitigation
Global Warming
Prevention
Cut fossil fuel use (especially
coal)
Shift from coal to
natural gas
Cleanup
Remove CO2 from smoke stack
and vehicle emissions
Store (sequester)
CO2 by planting trees
Improve energy efficiency
Shift to renewable energy
resources
Transfer energy efficiency and
renewable energy technologies
to developing countries
Reduce deforestation
Use more sustainable
agriculture and forestry
Limit urban sprawl
Reduce poverty
Slow population growth
Sequester CO2 deep underground
Sequester CO2 in soil by using
no-till cultivation
and taking cropland out
of production
Sequester CO2 in the deep ocean
Repair leaky natural gas pipelines
and facilities
Use animal feeds that reduce CH4
emissions by belching cows
Adaptatio
n
Develop crops that
need less water
Waste less water
Connect wildlife
reserves with
corridors
Move hazardous
material
storage tanks away
from coast
Move people away
from low-lying
coastal areas
Stockpile 1- to 5-year
supply of key foods
Prohibit new construction
on low-lying coastal areas
or build houses on stilts
Expand existing
wildlife
reserves
toward poles
Sea wall
…and dam glacial lakes, colony on Mars?, etc.
SOLUTIONS: Reducing the Threat
➢ We
can improve energy efficiency, rely more
on carbon-free renewable energy resources,
and find ways to keep much of the CO2 we
produce out of the troposphere.
SOLUTIONS:
Removing and Storing CO2
➢ Methods
for
removing CO2
from the
atmosphere or
from
smokestacks and
storing
(sequestering) it.
DEALING WITH GLOBAL WARMING:
Legal and cultural changes
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Tax greenhouse gas emissions, increase
subsidies and tax breaks for saving energy,
use cap-and-trade
Regulate CO2 and CH4, phase out polluting
energies (ie coal)
A crash program to MITIGATE and ADAPT
to global warming now is very likely to cost
less than waiting and having to deal with its
harmful effects later.
BUT… getting countries to agree on
reducing their greenhouse emissions is
difficult.
A 2006 poll showed that 83% of Americans
want more leadership from federal
government on dealing with global warming.
International Climate Negotiations:
The Kyoto Protocol
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Treaty on global warming (signed 1997) which first phase went
into effect January, 2005 with 189 countries participating.
It requires 38 participating developed countries to cut their
emissions of CO2, CH4, and N2O to 5.2% below their 1990
levels by 2012.
Developing countries were excluded.
• The U.S. did not sign, but California and Maine are participating.
• U.S. did not sign because developing countries such as China, India and
Brazil were excluded.
• Negotiations have failed to extend the original agreement after 2012.
Global Leadership
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Costa Rica aims to be the first country to become carbon
neutral by cutting its net carbon emissions to zero by 2030.
China has one of the world’s most intensive energy efficiency
programs (still a big polluter though).
By 2010, at least 30 U.S. states had set goals for reducing
greenhouse gas emissions.
Since 1990, local governments in more than 650 cities
around the world (including more than 450 U.S. cities) have
established programs to reduce their greenhouse gas
emissions.
California has adopted a goal of reducing its greenhouse gas
emission to 1990 levels by 2020, and 80% below by 2050.
Companies as well…see textbook
Individual Leadership
Section 15-7
HOW HAVE WE DEPLETED OZONE IN
THE STRATOSPHERE AND WHAT CAN
WE DO ABOUT IT?
OZONE DEPLETION IN THE
STRATOSPHERE
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Less ozone in the stratosphere allows for more harmful UV
radiation to reach the earth’s surface.
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The ozone layer keeps about 95% of the sun’s harmful UV radiation
from reaching the earth’s surface.
Chlorofluorocarbon (CFCs) have lowered the average concentrations
of ozone in the stratosphere.
In 1988 CFCs were no longer manufactured.
Ozone thinning: caused by CFCs and other ozone
depleting chemicals (ODCs).
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Increased UV radiation reaching the earth’s surface from ozone
depletion in the stratosphere is harmful to human health, crops,
forests, animals, and materials such as plastic and paints.
Ultraviolet light hits a chlorofluorocarbon
(CFC) molecule, such as CFCl3, breaking
off a chlorine atom and
leaving CFCl2.
Sun
Cl
UV radiation
The chlorine atom attacks
an ozone (O3) molecule,
pulling an oxygen atom off
it and leaving an oxygen
molecule (O2).
Summary of Reactions
CCl3F + UV Cl + CCl2F
Cl + O3 ClO + O2
Repeated
Cl + O Cl + O2
many times
Once free, the chlorine atom is off
to attack another ozone molecule
and begin the cycle again.
A free oxygen atom pulls
the oxygen atom off
the chlorine monoxide
molecule to form O2.
The chlorine atom
and the oxygen atom
join to form a chlorine
monoxide molecule
(ClO).
OZONE DEPLETION IN THE
STRATOSPHERE
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Since 1976, in Antarctica, ozone levels
have markedly decreased during October
and November.
Worst at cold poles b/c CFC associates
with ice crystals and builds up there.
In 2008, the area of ozone thinning was
still near its record high of 29 million
square kilometers (11 million square
miles), set in 2006.
Models indicate that even with immediate
and sustained action.
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About 60 years for the earth’s ozone layer
to recover the levels of ozone it had in
1980.
About 100 years for recovery to pre-1950
levels.
Natural Capital Degradation
Effects of Ozone Depletion
Human Health
• Worse sunburn
• More eye cataracts
• More skin cancers
• Immune system suppression
Food and Forests
• Reduced yields for some crops
• Reduced seafood supplies from reduced phytoplankton
• Decreased forest productivity for UV-sensitive tree species
Wildlife
• Increased eye cataracts in some species
• Decreased population of aquatic species sensitive to UV radiation
• Reduced population of surface phytoplankton
• Disrupted aquatic food webs from reduced phytoplankton
Air Pollution and Materials
• Increased acid deposition
• Increased photochemical smog
• Degradation of outdoor paints and plastics
Global Warming
• Accelerated warming because of decreased ocean uptake of CO2 from
atmosphere by phytoplankton and CFCs acting as greenhouse gases
Case Study: Skin Cancer
➢ Structure
of
the human
skin and
relationship
between
radiation
and skin
cancer.
PROTECTING THE OZONE LAYER
➢ To
reduce ozone depletion, we must stop producing
all ozone-depleting chemicals.
➢ A big step towards doing this was the Montreal
Protocol (1987). The most widely ratified treaty in UN
history. In 1992, the Copenhagen Protocol was an
amendment signed by 195 countries.
➢ If followed, ozone predicted to recover by 2050.
What Can You Do?
Reducing Exposure to UV Radiation
• Stay out of the sun, especially between 10 A.M. and 3 P.M.
• Do not use tanning parlors or sunlamps.
• When in the sun, wear protective clothing and sun–
glasses that protect against UV-A and UV-B radiation.
• Be aware that overcast skies do not protect you.
• Do not expose yourself to the sun if you are taking
antibiotics or birth control pills.
• Use a sunscreen with a protection factor of 15 or 30
anytime you are in the sun if you have light skin.
• Examine your skin and scalp at least once a month for
moles or warts that change in size, shape, or color or
sores that keep oozing, bleeding, and crusting over. If
you observe any of these signs, consult a doctor
immediately.
Three big ideas
• Prevent outdoor and indoor air pollution (from Part 1).
• Reducing the projected harmful effects of rapid climate
disruption during this century requires emergency
action.
• Continue phasing out the use of chemicals that have
reduced stratospheric ozone levels.