Download Climate Change, Global Warming, Ozone Depletion…

Global Environmental Change
CLIMATE CHANGE,
GLOBAL WARMING,
OZONE
DEPLETION…
…WHAT’S GOING
ON?
Stratospheric Ozone Depletion
https://www.youtube.com/watch?v=I1wrEvc2URE
What are Halogen Gases?
Where do CFC’s come from?
Where else can we find Ozone depleting chemicals?
How long do CFC’s last???
The chlorine atoms can break down tens of
thousands of ozone molecules before being
removed from the stratosphere. Given the
longevity of CFC molecules, recovery times are
measured in decades. It is calculated that a CFC
molecule takes an average of 15 years to go from
the ground level up to the upper atmosphere, and
it can stay there for about a century, destroying up
to one hundred thousand ozone molecules during
that time.
What are the effects of Ozone depletion?
 Skin cancer
 Cataracts
 Damage to crops
 Loss in productivity of phytoplankton in the ocean.,
Montreal Protocol
After a series of rigorous meetings and negotiations, the
Montreal Protocol on Substances that Deplete the Ozone Layer
was finally agreed upon on 16 September 1987 at the
Headquarters of the International Civil Aviation Organization
in Montreal. The Montreal Protocol stipulates that the
production and consumption of compounds that deplete ozone
in the stratosphere--chlorofluorocarbons (CFCs), halons,
carbon tetrachloride, and methyl chloroform--are to be phased
out by 2000 (2005 for methyl chloroform). Scientific theory
and evidence suggest that, once emitted to the atmosphere,
these compounds could significantly deplete the stratospheric
ozone layer that shields the planet from damaging UV-B
radiation.
Back to the Troposphere
 Climate change is the fastest-developing area of
environmental science
What is Climate?
 Climate = the average and variations of weather over a long period
of time (~30 years)
The changes in temperature, moisture, wind, precipitation, etc.
Above: Global average for atmospheric water vapor.
What is Weather?
 Weather = all natural phenonmena within the
atmosphere at a given time (hours to days)
 Short-term conditions at localized sites
What is climate change?
 Global climate change = describes trends and
variations in Earth’s climate

Temperature, precipitation, storm frequency
 Global warming and climate change are not the
same
 Global warming = an increase in Earth’s average
temperature

Only one aspect of climate change
Global warming
 Climate change and global warming refer to current
trends

Earth’s climate has varied naturally through time
 The current rapid climatic changes are due to humans
 Fossil fuel combustion and deforestation
 Understanding climate change requires understanding
how our planet’s climate works
The sun and atmosphere keep Earth warm
 Four factors exert the most influence on climate
 The sun = without it, Earth would be dark and frozen
 Supplies most of Earth’s energy
 The atmosphere = without it, Earth’s temperature
would be much colder
 The oceans = shape climate by storing and
transporting heat and moisture
 How Earth spins, tilts, and moves through space
influence how climate varies over long periods of time
The Climate System
Oceans
Atmosphere
 The Earth has many
Ice
Biosphere
Land
different systems
that interact with
each other in
different ways.
The fate of solar radiation
• The atmosphere, land, ice, and water absorb 70% of
incoming solar radiation
Greenhouse gases warm the lower atmosphere
 As Earth’s surface absorbs solar radiation, the surface
increases in temperature and emits infrared radiation
 Greenhouse gases = atmospheric gases that absorb
infrared radiation

Water vapor, ozone, carbon dioxide, nitrous oxide, methane,
halocarbons [chlorofluorocarbons (CFCs)]
 After absorbing radiation, greenhouse gases re-emit
infrared energy, losing some energy to space
 Greenhouse effect = energy that travels
downward, warming the atmosphere and the planet’s
surface
Modern Climate Systems
 Atmosphere and Greenhouse Effect
 The Earth’s atmosphere keeps it around 30°C warmer
than it would otherwise be.
 This is the Greenhouse Effect
The temperature of the Earth
depends on the amount of energy we
receive from the sun versus the
amount of energy lost back out to
space.
The greenhouse effect is natural
 Greenhouse gases have always been in the
atmosphere
 We are not worried about the natural greenhouse
effect

Anthropogenic intensification is of concern
 Global warming potential = the relative ability of one
molecule of a greenhouse gas to contribute to
warming


Expressed in relation to carbon dioxide (potential = 1)
Methane is 25 times as potent as carbon dioxide
Carbon dioxide is of primary concern
 It is not the most potent greenhouse gas, but it is
extremely abundant

The major contributor to the greenhouse effects
 CO2 exerts six times more impact than methane,
nitrous oxide, and halocarbons combined
 Deposition, partial decay, and compression of organic
matter (mostly plants) in wetlands or marine areas led
to formation of coal, oil, and natural gas

These deposits remained buried for millions of years
The Carbon Cycle
What caused levels of CO2 to increase?
 Burning fossil fuels transfer CO2 from lithospheric
reservoirs into the atmosphere

The main reason atmospheric carbon dioxide concentrations
have increased so dramatically
 Deforestation contributes to rising atmospheric CO2
 Forests serve as reservoirs for carbon
 Removing trees reduces the carbon dioxide absorbed from the
atmosphere
 Human activities increased atmospheric CO2 from
280 parts per million (ppm) to 389 ppm

The highest levels in more than 800,000 years
Other greenhouse gases add to warming
 Methane = fossil fuels, livestock, landfills, crops (rice)

Levels have doubled since 1750
 Nitrous oxide = feedlots, chemical manufacturing plants,
auto emissions, and synthetic nitrogen fertilizers
 Ozone levels have risen 36% due to photochemical smog
 Halocarbon gases (CFCs) are declining due to the Montreal
Protocol
 Water vapor = the most abundant greenhouse gas


Contributes most to the natural greenhouse effect
Concentrations have not changed
U.S. emissions of major greenhouse gases
Feedback complicates our predictions
 Tropospheric warming will transfer more water to the air

But the effects are uncertain
 A positive feedback loop = more water vapor … more
warming … more evaporation … more water vapor …
 A negative feedback loop = more water vapor … more
clouds … shade and cool Earth OR increase evaporation
 Minor modifications of the atmosphere can lead to major
effects on climate
Most aerosols exert a cooling effect
 Aerosols = microscopic droplets and particles
 They have either a warming or a cooling effect
 Soot (black carbon aerosols) causes warming by
absorbing solar energy

But most tropospheric aerosols cool the atmosphere by
reflecting the sun’s rays
 Sulfate aerosols produced by fossil fuel combustion
may slow global warming, at least in the short term

Volcanic eruptions reduce sunlight reaching Earth’s surface
and cool the Earth
Radiative forcing expresses change in energy
 Radiative forcing = the amount of change in thermal
energy that a given factor causes


Positive forcing warms the surface
Negative forcing cools it
Earth is experiencing
radiative forcing of 1.6
watts/m2 more than it is
emitting to space – enough
to alter the climate
Milankovitch cycles influence climate
 Milankovitch cycles =
periodic changes in Earth’s
rotation and orbit around the
sun

Alter the way solar radiation is
distributed over Earth
 These cycles modify patterns
of atmospheric heating


Triggering climate variation
For example, periods of cold
glaciation and warm interglacial
times
Solar output and ocean absorption
influence climate
 Solar output = the sun varies in the radiation it emits
 Variation in solar energy (e.g., solar flares) has not been great
enough to change Earth’s temperature
 Radiative forcing is 0.12 watts/m2 – much less than human
causes
 Ocean absorption = the ocean holds 50 times more
carbon than the atmosphere

Slowing global warming but not preventing it
 Warmer oceans absorb less CO2
 A positive feedback effect that accelerates warming
Ocean circulation influences climate
 Ocean circulation = ocean water exchanges heat with
the atmosphere,

Currents move energy from place to place
 The ocean’s thermohaline circulation system affects
regional climates


Moving warm tropical water north, etc.
Greenland’s melting ice sheet will affect this flow
 El Niño–Southern Oscillation (ENSO)
 Shifts atmospheric pressure, sea surface temperature, ocean
circulation in the tropical Pacific
Direct measurements tell us about the present
 We document daily fluctuations in weather
Precise thermometer measurements over the past 100
years
 Measuring of ocean and
atmospheric chemistry began in
1958
 Precise records of historical
events


Droughts, etc.
Atmospheric CO2 concentrations
have increased from 315 ppm to
389 ppm
How Do We Know about Past Climate Systems
1. Early human record
cc. W.V. Bailey
Rock paintings provide evidence of
fertile Sahara region (now desert)
6,000 years ago.
Tourism NT http://www.travelnt.com
Past Climate Systems
2. Geomorphology
River deltas
show where
rivers entered the
ocean or a lake.
Above: A “U” shaped valley
shows that it was formed by
a glacier.
Past Climate Systems
4. Ice cores
Ice cores can preserve
seasonal layering.
Studying the chemistry of
each layer can give clues
about climate change.
GISP2 ice core at 1837m depth with clearly visible annual layers.
Ice cores from Antarctica
 Ice cores let us go back in time 800,000 years
 Reading Earth’s history across eight glacial cycles
Is the Climate Changing?
What are the current climate trends?
Global temperature for the
last 150 years
cc. Robert A. Rohde http://www.globalwarmingart.com/wiki/Image:Instrumental_Temperature_Record_png
Temperatures continue to increase
 Average surface temperatures increased 0.74 °C
since 1906



Most of the increase occurred in the last few decades
Extremely hot days have increased
The 16 warmest years on record have been since 1990
The future will be hotter
 In the next 20 years, temperatures will rise 0.4 °C
 At the end of the 21st century, temperatures will be 1.8–4.0
°C higher than today’s
 We
will have unusually hot days and heat waves
 Polar areas will have the most intense warming
 Sea surface temperatures will rise
 Hurricanes and tropical storms will increase

In power and duration
Temperatures will rise globally
Projected increases in surface temperature
for 2090–2099 relative to 1980–1999
Precipitation is changing, too
 Some regions are receiving more precipitation than
usual, and others are receiving less
 Droughts have become more frequent and severe

Harming agriculture, promoting soil erosion, reducing water
supplies, and triggering fires
 Heavy rains contribute to flooding
 Killing people, destroying homes, and inflicting billions of
dollars in damage
Projected changes in precipitation
Precipitation will increase at high latitudes
and decrease at low and middle latitudes
Melting snow and ice
 Mountaintop glaciers are disappearing
 Glaciers on tropical mountaintops have disappeared
 The remaining 26 of 150 glaciers in Glacier National Park will be
gone by 2020 or 2030
 Reducing summertime water supplies
 Melting of Greenland’s Arctic ice sheet is accelerating
 Warmer water is melting Antarctic coastal ice shelves
 Interior snow is increasing due to more precipitation
 Melting ice exposes darker, less-reflective surfaces,
which absorb more sunlight, causing more melting
Coral reefs are threatened
 Coral reefs are habitat for food fish
 Snorkeling and scuba diving sites for tourism
 Warmer waters contribute to coral bleaching
 Which kills corals
 Increased CO2 is acidifying the ocean
 Organisms can’t build their exoskeletons
 Oceans have already decreased by 0.1 pH unit
 Enough to kill most coral reefs
Climate change affects organisms and ecosystems
 Organisms are adapted to their environments
 They are affected when those environments change
 Global warming modifies temperature-dependent
phenomena (e.g., timing of migration, breeding)
 Animals and plants will move toward the poles or
upward in elevation


20–30% of species will be threatened with extinction
Rare species will be pushed out of preserves
 Droughts, fire, and disease will decrease plant growth
 Fewer plants means more CO2 in the atmosphere
Climate change affects people
 Societies are feeling the impacts of climate change
 Agriculture: shortened growing seasons, decreased
production, crops more susceptible to droughts

Increasing hunger
 Forestry: increased fires, invasive species
 Insect and disease outbreaks
 Health: heat waves and stress can cause death
 Respiratory ailments, expansion of tropical diseases
 Disease and sanitation problems from flooding
 Drowning from storms
Impacts of climate change
The Arctic has suffered
the most so far
U.S. temperatures will continue to rise
Impacts of climate change will vary
Predictions from two climate models
By 2050, Illinois will
have a climate like
Missouri’s
By 2090, it will have a
climate like Louisiana’s
Causes and consequences of climate change
Shall we pursue mitigation or adaptation?
 Most people accept that our planet is changing
 They are searching for solutions
 Mitigation = pursue actions that reduce greenhouse
gas emissions to lessen severity of future climate
change

Energy efficiency, renewable energy, protecting soil,
preventing deforestation
 Adaptation = accept that climate change is
happening


Pursue strategies to minimize its impacts on us
Seawalls, leaving the area, coping with drought, etc.
 Both are necessary
Electricity generation
A coal-fired,
electricity-generating
power plant
 The largest source of U.S. CO2 emissions
 70% of electricity comes from fossil fuels
 Coal causes 50% of emissions
 To reduce fossil fuel use:
 Encourage conservation and efficiency
 Switch to cleaner and renewable energy sources
Conservation and efficiency
 We can make lifestyle choices to reduce electricity use
 Use fewer greenhouse-gas-producing appliances
 Use electricity more efficiently
 The EPA’s Energy Star Program rates appliances,
lights, windows, etc. by their energy efficiency



Replace old appliances with efficient ones
Use compact fluorescent lights
Use efficient windows, ducts, insulation, heating and cooling
systems
Sources of electricity
 We need to switch to clean energy sources
 Nuclear power, biomass energy, solar, wind, etc.
 We need to consider how we use fossil fuels
 Switching from coal to natural gas cuts emissions 50%
 Cogeneration produces fewer emissions
 Carbon capture = removes CO2 from power plant
emissions
 Carbon sequestration (storage) = storing
carbon underground where it will not seep out


Use depleted oil and gas deposits, salt mines, etc.
We can’t store enough CO2 to make a difference
Transportation
 2nd largest source of U.S.
greenhouse gases

Cars are inefficient
 Ways to help:
 More efficient cars
 Hybrid or electric cars
 Drive less and use public
transportation
 Live near your job, so you can
bike or walk
U.S. public transportation
saves 4.2 billion gallons of
gasoline and 37 million
metric tons of CO2
emissions
We can reduce emissions in other ways
•
Agriculture: sustainable land management lets soil store more
carbon


Reduce methane emissions from rice and cattle
Grow renewable biofuels
 Forestry: reforest cleared land, preserve existing
forests

Sustainable forestry practices
 Waste management: treating wastewater


Generating electricity by incinerating waste
Recovering methane from landfills
 Individuals can recycle, compost, reduce, or reuse
goods
Questions to be answered…
 How fast will the sea level rise?
 How much warmer will it get?
 When will the Arctic Ocean be ice-free?
 Will the water cycle accelerate?
 Are climate extremes increasing?
 Will there be abrupt changes?
Boiling Frog Syndrome