Sources of Feed back

1
Sources of Feed back

• Positive
• Water vapor
• Clouds
• Ice albedo
• Arctic methane release
• Reduced carbon dioxide absorption in the oceans

• Negative
• Lapse rate

2
Negative feedback

• Lapse Rate
• Increased heating means increased IR emission
• Global warming reduces the rate of temperature
  decrease with height, which means more long
  wavelength radiation will be emitted by the upper
  atmosphere
• This will weaken the greenhouse effect

3
Positive feedback

• Water vapor
• Warming increases the amount of water vapor in
  the atmosphere, which increases the warming since
  water vapor is also a greenhouse gas
• Clouds
• Act as a blanket, reflect IR radiation downward
  toward the surface
• Ice albedo
• Melting ice reveals land and water, both reflect
  less light than ice-more warmth is absorbed
  increasing warming
• Arctic methane release
• Warming releases sources of carbon dioxide
• Reduce carbon dioxide absorption in oceans
• Warm waters favor the growth of plankton rather
  than diatoms-diatoms are more efficient carbon
  dioxide absorbers

4
Global dimming

• An effect that has been counteracting some of
  global warming from about 1960 forward
• Aerosols produced by volcanoes and pollutants
  such as sulfur dioxide reflect incoming sunlight
• Soot suspended in the atmosphere, it can absorb
  solar radiation and heat the atmosphere, but cool
  the surface

5
What are we seeing

• Besides the increases in Temperature
• Worlds glaciers are melting
• Arctic sea ice is reducing in both extent ( 9
  reduction in area per decade) and thickness
  (15-40 in thickness in the last 30 years)
• Ocean levels are rising-both due to melting of
  Antarctic ice and thermal expansion of sea water
• Longer growing seasons
• Thawing of permafrost in Alaska
• Coral reef bleaching-whitening of reefs due to
  increased temperature
• Earlier plant flowering
• Earlier bird arrivals
• Shifting of animal ranges poleward
• More frequent EL Nino-warming of the Pacific
  ocean surface temperatures-causes changes in
  local weather patterns

6
Global warming-the debate

• The fact that the Earth is warming is not a
  matter of debate, the evidence is clear
• The fact that global carbon dioxide levels have
  increased is also clear
• The debate centers around how much of it is
  caused by human involvement vs a natural cycle
• Think about it in terms of the steps in the
  scientific method

7
Global warming in the context of the scientific
method

• Observations-Earths temperature is warming
• Hypothesis-due to a man-made increase in green
  house gases
• Testing the hypothesis-many scientists hold
  different views and interpret data differently,
  but the consensus is that it is due to increases
  in greenhouse gasses from man made sources.
• Until the data is incontrovertible, there will
  always be naysayers. Thats ok, they keep us
  honest and push the method forward-as long as
  they are within the realm of the scientific
  method
• Lots of examples like this in modern science
  (evolution, big bang, cosmological
  interpretations of galaxy redshifts)

8
Dissenting opinions

• American Association of Petroleum Geologists was
  the last scientific body to acknowledge human
  influence on climate change
• Individual scientists fall into 5 categories
• Believe global warming is not occurring or has
  ceased
• Believe accuracy of IPCC climate projections is
  questionable
• Believe global warming is primarily caused by
  natural processes
• Believe cause of global warming is unknown
• Believe global warming will benefit human society
• In the end, only time will tell.

9
Prognosis

• How do we know what is going to happen?
• We dont , but it can be predicted
• We call these global climate models
• Based on physics (fluid dynamics and radiative
  transfer, for eg.)
• Different models consider different effects, have
  different inputs and give a range of results
• Model validity is verified by using them to
  predict past and current climate conditions
• No, they are not perfect

10
Projections
11
Prognosis

• Sea level rise of up to 1 foot
• Reductions in ozone layer
• More intense, less frequent hurricanes
• Ocean ph and oxygen level reduced
• Spread of diseases including malaria, Lyme
  disease, cholera and bubonic plague
• Extinctions of plant an animal species
• Population growth due to less deaths from cold
  weather
• Changes in rainfall patterns

12
What are we doing about it

• Kyoto Protocol
• International environmental treaty to achieve
  stabilization of greenhouse gas concentrations in
  the atmosphere at a level that would prevent
  man-made interference with the climate
• establishes legally binding commitments for the
  reduction of four greenhouse gases (carbon
  dioxide, methane, nitrous oxide, sulphur
  hexafluoride), and two groups of gases
  (hydrofluorocarbons and perfluorocarbons)
  produced by (industrialized) nations,
• general commitments for all member countries.
• Did not impose limitations on developing
  countries (such as China)
• initially adopted for use on 11 December 1997 in
  Kyoto, Japan
• entered into force on 16 February 2005.
• Signed but not ratified by the US

13
Kyoto

• industrialized countries agreed to reduce their
  collective GHG emissions by 5.2 compared to the
  year 1990.
• National limitations range from 8 reductions for
  the European Union and some others to 7 for the
  United States, 6 for Japan, and 0 for Russia.
• The treaty permitted GHG emission increases of 8
  for Australia and 10 for Iceland.

14
US position

• US signed in 1998, but this was symbolic-treaty
  is not binding until ratified.
• Yet the US is the largest per capita emitter of
  carbon dioxide
• Prior to Kyoto, (though with a knowledge of what
  it said) the US Senate passed a resolution that
  stated stated the sense of the Senate was that
  the United States should not be a signatory to
  any protocol that did not include binding targets
  and timetables for developing nations as well as
  industrialized nations or "would result in
  serious harm to the economy of the United
  States
• Main concern is the economic losses associated
  with instituting the caps on carbon emission
• Neither the Clinton nor Bush administration
  submitted the treaty for ratification
• Obama Administrations position is that the
  treaty is about to end, there is no point in
  ratifying it (it has a little less than 3 years
  left)
• States and cities have adopted initiatives to cap
  carbon emissions on their own, based at least in
  part on Kyoto.

15
Reasons for opposition

• Global socialism-a scheme to transfer wealth to
  third world countries and or slow the growth of
  the worlds industrialized democracies
• Doesnt go far enough to curb GHG emissions
• Costs outweigh benefits
• Using a single base year (1990) may result in
  inequities in the caps

16
Next step-beyond Kyoto

• Meeting in Copenhagen in December 2009
• The Copenhagen Accord was drafted by the US,
  China, India, Brazil and South Africa on December
  18, and judged a "meaningful agreement" by the
  United States government.
• It was "taken note of", but not "adopted", in a
  debate of all the participating countries the
  next day, and it was not passed unanimously.
• The document recognized that climate change is
  one of the greatest challenges of the present day
  and that actions should be taken to keep any
  temperature increases to below 2C.
• The document is not legally binding and does not
  contain any legally binding commitments for
  reducing CO2 emissions.
• Many countries and non-governmental organizations
  were opposed to this agreement, but, as of
  January 4, 2010, 138 countries have signed the
  agreement.

17
Cap and Trade

• An environmental policy that caps emissions while
  giving source flexibility in how they comply with
  those caps-uses economic incentives to get
  compliance
• A limit or cap on the amount of a pollutant that
  can be emitted is set. Companies or other groups
  are issued emission permits and are required to
  hold an equivalent number of allowances (or
  credits) which represent the right to emit a
  specific amount. The total amount of allowances
  and credits cannot exceed the cap, limiting total
  emissions to that level. Companies that need to
  increase their emission allowance must buy
  credits from those who pollute less called a
  trade. In effect, the buyer is paying a charge
  for polluting, while the seller is being rewarded
  for having reduced emissions by more than was
  needed. Thus, in theory, those who can reduce
  emissions most cheaply will do so, achieving the
  pollution reduction at the lowest cost to
  society.
• Allowed under Kyoto for nations to sell their
  credits.

18
American Clean Energy and Security Act

• Also known as the Waxman-Markey Act
• Proposes a cap and trade system for Greenhouse
  Gas emissions
• Requires electric utilities to meet 20 of their
  electricity demand through renewable energy
  sources and energy efficiency by 2020.
• Invests in new clean energy technologies and
  energy efficiency, including renewable energy,
  carbon capture and sequestration, electric and
  other advanced technology vehicles, and basic
  scientific research and development.
• Protects consumers from energy price increases.
  According to estimates from the Environmental
  Protection Agency, the reductions in carbon
  pollution required by the legislation will cost
  American families less than a postage stamp per
  day.
• The bill requires a 17-percent emissions
  reduction from 2005 levels by 2020 this would
  reduce United States' emissions by about 80
  percent by 2050. Complementary measures in the
  legislation, such as investments in preventing
  tropical deforestation, will achieve significant
  additional reductions in carbon emissions.
• It includes a renewable electricity standard)
  requiring each electricity provider who supplies
  over 4 million MWh to produce 20 percent of its
  electricity from renewable by 2020. There is a
  provision whereby 5 of this standard can be met
  through energy efficiency savings, as well as an
  additional 3 with certification of the Governor
  of the state in which the provider operates.
• It provides for modernization of the electrical
  grid
• It provides for expanded production of electric
  vehicles
• It mandates significant increases in energy
  efficiency in buildings, home appliances, and
  electricity generation.