Chapter 18 Climate Change and Ozone Loss

1
Chapter 18Climate Change and Ozone Loss
2
Temperatures in the Past

• Not new or unusual
• Last 90,000 years prolonged periods of global
  cooling and global warming
• Global cooling thick glacial ice covered much
  of the earths surface
• Interglacial warming follows a global cooling
  (We live in interglacial cooling) Temperature
  changes are analyzed by
• Radioisotopes in rocks and fossils
• Plankton and radioisotopes in ocean sediments
• Pollen from lake bottoms, bogs, and volcanic ash
• Ice cores from ancient glaciers
• Tree rings
• Radioisotopes in coral
• Historical records
• Temperature measurements

3
Greenhouse Effect

• Greenhouse effect warms the earths lower
  troposphere and surface certain greenhouse gases
  absorb some of the infrared radiation (heat)
  radiated by the earths surface. The molecules
  vibrate and transform the absorbed energy into
  longer wavelength heat in the troposphere.
• Heat released by the molecules of the greenhouse
  gases is spread through the atmosphere by
  convection ? Tropospheric heating effect
  (greenhouse effect)

4
Examples of Greenhouse Gases

• Greenhouse Gases
• Water Vapor controlled by the water cycle
• Carbon Dioxide - controlled by the carbon cycle
• Methane
• Nitrous Oxide
• Chloroflourocarbons (CFCs)
• Hydrochlorofluorocarbons (HCFCs)
• Hydrofluorocarbons (HFCs)
• Halons
• Carbon tetrachloride

5
What is Global Warming?

• Since the beginning of the industrial revolution,
  there has been a sharp rise in
• Fossil Fuels
• Deforestation, clearing, and burning of
  grasslands to raise crops
• Cultivation of rice in paddies and use of
  inorganic fertilizers
• Largest contributors to current CO2 emissions
• Coal burning power plants and industrial power
  plants
• Gasoline burning vehicles
• Most scientists believe that the increased inputs
  of CO2 and other greenhouse gases from human
  activities will
• Enhance the earths natural greenhouse effect
• Raise the average global temperature near that
  earths surface

6
Are We Experiencing Global Warming?

• Yes, evidence suggests it is occurring
• Ice core samples
• Temperature measurements

7
Correlations and Sources of Change

• Correlation between
• Increases in fossil fuel use
• Increases in atmospheric concentrations of CO2
• Increases in global temperature between 1970 and
  2000
• Possible sources of changes
• Natural climate fluctuations
• Changes in climate from human activities
• Combination of both factors

8
Evidence of Global Warming

• Increased temperatures and some melting of
  land-based ice caps and floating ice at the
  earths poles and Greenland
• Shrinking of some glaciers
• An average global sea level rise
• Northward migration of some fish, tree, and other
  species to find optimum temperatures
• Earlier springs and later autumn frosts
• CO2 concentration is higher than it has been in
  the last 420,000 years
• About 75 of emissions of CO2 are due to fossil
  fuel burning and the rest is due to
  deforestation, agriculture, and other human
  changes in land use
• The 20th century was the hottest century in the
  past 1,000 years
• The global temperature of the troposphere has
  risen about 1 degree F (most taking place since
  1946)
• Since 1861, nine of the ten warmest years
  occurred since 1990

9
Results of Rapid Climate Change

• Affect the availability of water resources by
  altering rates of evaporation and precipitation
• Shift areas where crops can be grown
• Change average sea levels
• Alter the structure and location of the worlds
  biomes

10
Arctic Warnings

• Temperatures tend to be greater at and near the
  poles because as the atmosphere warms, it causes
  more convection that transfers the surplus heat
  from the equator
• Since 1980 Surface temperatures at nine
  stations have rise more than the average global
  temperature and are projected to rise more
  quickly
• The ice reflects 80 of the sunlight it receives.
  If it doesnt do this, the water would absorb 80
  of its sunlight input which would affect global
  temperatures
• Widespread melting would amplify warming of the
  Arctic region
• Reroute warm ocean currents and weather patterns
  further south
• Cause significant cooling in parts of the N.
  hemisphere
• Arctic tundra soil has been warmed so much that
  is has been giving off more CO2 than it absorbs

11
Antarctica Warnings

• Arctic Cap contains 70 of the worlds fresh
  water and 90 of its reflective ice
• Average temperature has risen 2.5 degrees C in
  summer and 5.6 degrees C in winter
• Large pieces of ice shelf have begun breaking off
  (process called calving)
• Could cause the increase in sea levels

12
Greenland Warnings

• Greenland the worlds largest island
• Holds 6 of the worlds fresh water
• Close to the equator, so more likely to melt
• Average sea levels could rise by 4 6 meters
• Would cause flooding in low-lying coastal areas
• Could shut off currents such as the Gulf Stream
  and North Atlantic which keep Europe warmer than
  it would otherwise be.

13
Modeling Changes

• Mathematical models of the global air circulation
  systems and run them on super computers
• General Circulation Models (GCMs) provide a 3D
  representation of how energy, air masses, and
  moisture flow through the atmosphere
• Ocean circulation models
• Interactions between the atmosphere and the ocean
• Changes in solar output
• Inputs of aerosols into the atmosphere
• Improved estimate of the effect of clouds on
  climate
• Models allow scientists to
• Account for past changes
• Project future changes

14
Scientific Consensus on Climate Change

• Intergovernmental Panel on Climate Change (IPCC)
• Created by the UN and World Meteorological
  Organization
• A network of 2,000 of the leading climate experts
  from 70 nations
• Published reports on past changes in global
  temperatures and climate models projecting future
  changes in average global temperatures andclimate
• Most warming is due to human activities
• There is a 90 95 change that the earths
  surface temperature will increase by 1.4- 5.8
  degrees C between 2000 and 2100.

15
Why Do People Not Believe There is a Problem?

• Insufficient knowledge about natural climate
  variables
• Computer models are improving, but are not
  reliable
• May be less damaging than people think and not
  necessarily caused by human activities
• Global warming can be beneficial for some
  regions increase crop productivity due to more
  rainfall and longer growing seasons

16
Will The Earth Continue to Warm?

• The average temperature at the earths surface
  has increased in the past 20 years
• It is highly likely that it will continue, but we
  do not know for sure
• Human and natural factors might amplify or dampen
• Could influence how much and how fast
  temperatures might climb or drop
• Could influence what effects might happen in
  various areas
• Rise in temperatures will not be distributed
  evenly over the surface
• Higher over land than over oceans
• Greater in higher latitudes near the earths
  poles
• Higher in many inland regions in the northern
  latitudes

17
Earths Reflectivity

• Albedo ability to reflect light.
• White or shiny surfaces reflect most of the
  sunlight that hits them
• Albedo increases when polar ice caps expand and
  decrease when it melts
• Positive Ice Albedo Affect could accelerate
  global warming as the ice shrinks it is replaced
  by less reflective water or land

18
Oceans and Climate

• The oceans remove about 29 of the excess CO2
• The solubility of CO2 in ocean water decreases
  with increasing temperature so, if the oceans
  heat up, some of the dissolved CO2 can be
  released into the atmosphere.
• Oceans absorb heat from the atmosphere and
  transfer it to the deep ocean where it can be
  stored
• Could affect ocean currents (which are driven by
  differences in water density and winds) because
  the increased fresh water might slow or disrupt
  the conveyor belt and decrease the amount of heat
  it brings to the North Atlantic region.
• Changes in sea level could affect
• The amount of heat and CO2 that can be stored in
  the ocean
• Changes in the earths biomes

19
Cloud Feedback System

• Warmer temperatures increase evaporation of
  surface water and creates more clouds
• Could have a warming effect by absorbing and
  releasing heat into the troposphere
• Could have a cooling effect by reflecting
  sunlight back into space.
• Depends on whether it is day or night
• The type, coverage, and altitude of clouds
• Size and number of water droplets formed in
  clouds

20
Increased CO2 and Plants

• More CO2 in the atmosphere could increase the
  rate of photosynthesis in areas with adequate
  amounts of water and other soil nutrient ? This
  would remove more CO2 from the atmosphere and
  help slow atmospheric warming
• Slow as the plants reach maturity and take up
  less CO2
• When the plants die, the carbon they store is
  returned to atmosphere as CO2
• Varies with the different types of plants and in
  different climate zones

21
Warm Air and Methane

• Can increase the release of methane from
• Bogs and other wetlands
• Icelike compounds called methane hydrates
  melting the permafrost or extracting to increase
  natural gas supplies

22
Soils and CO2

• When a plant dies and is decomposed, some of its
  carbon returns to the atmosphere as CO2 and some
  is released into the soil
• Can we slow global warming by increasing the
  amount of carbon stored in soils by planting more
  trees, improving forest management, and reducing
  soil erosion?
• Found that much was released back into the
  atmosphere

23
Rapid Climate Change and Adaptations

• If it happens moderately, people might be able to
  adapt to changes taking place.
• However, if it happens quickly, we might not have
  enough time and money to
• Switch food-growing regions
• Relocate millions of people from low-lying
  coastal areas
• Build systems of dikes and levees to help protect
  the large portion of the worlds population
  living near coastal areas.

24
Global Warming Will Affect

• Water Distribution
• Plant and Animal Distribution
• Biodiversity
• Ocean Currents
• Sea Level
• Extreme Weather
• Human Health

25
Warming in Different Regions

• Africa
• Asia
• Europe
• Latin America
• North America
• Polar Areas
• Small Island States

26
What Are Our Options?

• Do nothing
• Do more research before acting
• Act now to reduce the risks from climate change
• Act now as a part of a no-regrets strategy (Even
  if we dont know the effects)

27
What Can Humans Do?

• Waste less energy by improving energy efficiency
• Use less oil and coal
• Rely more on cleaner energy sources such as
  natural gas, solar, wind, and hydrogen
• Shifting to organic farming and other more
  sustainable forms of agriculture
• ?Could reduce the threats of global warming, air
  pollution, deforestation, and biodiversity loss

28
What Can Governments Do?

• Impose output carbon taxes on each unit of CO2
  emitted by fossil fuels and input energy taxes on
  each unit of fossil fuel that is burned
• Decrease taxes on income, labor, and profits to
  match any increases in consumption taxes on
  carbon emissions or fossil fuel use
• Greatly increase government subsidies for
  energy-efficiency and renewable energy
  technologies, sustainable agriculture
• Fund the transfer of energy efficient and
  renewable energy technologies from developed
  countries to developing countries

29
Economic Consequences and the Marketplace

• Will cost the worlds economy more than 300
  billion annually by 2050.
• Some say that reducing CO2 gases is too costly
• Others say it will boost the global economy,
  provide needed jobs, and cost much less than
  trying to deal with the harmful effects of these
  problems
• Agree to global and national limits on greenhouse
  gas emissions
• Encourage industries and countries to meet these
  limits by selling and trading greenhouse gas
  emission permits
• Why people dont like this idea
• Difficult to monitor
• Can the worlds countries divide up greenhouse
  gas emission credits?

30
Can We Store CO2?

• Possible ways to remove or store CO2
• Immature trees
• Plants that store it in the soil
• Deep underground reservoirs
• Deep Ocean
• Issues of biodiversity, cost
• NEED MORE RESEARCH

31
Any Tecnofixes?

• Adding iron to the oceans to stimulate the growth
  of marine algae
• Unfurling gigantic foil-surfaced sun mirrors in
  space or placing such mirrors on satellites to
  reduce solar input
• Releasing trillions of reflective balloons filled
  with helium into the atmosphere
• Injecting sunlight-reflecting sulfate
  particulates or firing sulfur dioxide cannonballs
  into the stratosphere to cool the earths surface

32
Kyoto Treaty

• 1992 Earth Summit - 106 nations approved a UN
  Framework Convention on Climate Change
• Two Basic Principles
• Scientific uncertainty must not be used to avoid
  precautionary action
• Industrial nations must take the lead in slowing
  down the projected rate and degree of global
  warming so that its effects can be managed
  without disrupting economies, societies, and the
  earths biodiversity
• Did not require countries to reach this goal, and
  most countries did not achieve it.
• 1997 161 nations met in Kyoto, Japan to
  negotiate a new treaty to help stop global
  warming
• Would require 38 developed countries to cut
  greenhouse emissions to an average of about 5.2
  below 1990 levels by 2012
• Not require developing countries to make any cuts
  until a later version
• Allow emissions trading among participating
  countries

33
US and the Kyoto Treaty

• Should the United States Ratify the Kyoto Treaty?
• Has not been ratified because of
• Its failure to require emission reductions from
  developing countries
• Intensive lobbying by coal, oil, steel, chemical,
  and automobile companies
• 2001 Bush withdrew US participation
• The US
• Will not reduce CO2 and other emissions.
• Will not have US industries report their annual
  emissions

34
Threat from Ozone Depletion

• A layer of ozone in the lower stratosphere keeps
  about 95 of the suns harmful UV radiation from
  reaching the earths surface.
• Ozone depletion is a serious threat to humans,
  many other animals, and the sunlight-driven
  primary producers (mostly plants) that support
  the earths food chains and webs.

35
How is the Ozone Depleted?

• Chlorofluorocarbon (CFC) 1930 chemically
  stable, odorless, nonflammable, nontoxic, and
  noncorrosive compounds seem to be dream chemicals
• Realized that they were lowering the average
  concentration of ozone in the stratosphere and
  called for an immediate ban
• They are insoluble in water and chemically
  unreactive
• They rise into the stratosphere mostly through
  convection, random drift, and the mixing of air
• They break down under the influence of
  high-energy UV radiation which releases reactive
  chlorine atoms, which speed up the breakdown of
  O3 into O2 and O in a cyclic chain of chemical
  reactions ? Ozone is destroyed faster than it is
  formed
• Each CFC can last for 65 385 years

36
Life in the UV Zone

• Affects
• Humans
• Food and Forests
• Wildlife
• Air Pollution and Materials
• Global Warming

37
Protecting the Ozone Layer

• We should immediately stop producing all
  ozone-depleting chemicals (ODCs)
• It will still take 50 years for the ozone to
  return to its original levels
• Substitutes are available for CFCs and others are
  being developed

38
Any Technofixes?

• Launch 20 -30 radio controlled blimps into the
  stratosphere above Antarctica and inject
  negatively charged electrons to react with the
  chlorine
• Using tens of thousands of lasers to blast CFCs
  out of the atmosphere before they reach the
  stratosphere

39
Global Warming Vs. Ozone

• Ozone problem has been easier to fix...
• Global Warming has more barriers.