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Introduction to Global Warming and Climate Change

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Introduction to Global Warming and Climate Change APES/MOC/2007-2008 – PowerPoint PPT presentation

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Title: Introduction to Global Warming and Climate Change


1
Introduction to Global Warming and Climate Change
  • APES/MOC/2007-2008

2
Factors That Affect Climate Changes
  • Ice core data shows that Earths temperature
    varies over time
  • Earths energy balance and albedo surfaces
  • Variation in insolation
  • Milankovitch cycles
  • Volcanoes, dust
  • Ocean currents
  • El Nino/La Nina cycles

3
Earths Energy Balance
Incoming solar radiation energy reflected
energy absorbed
4
  • Scientists from the National Aeronautics and
    Space Administration (NASA), The Earth Institute
    at Columbia University, and Lawrence Berkeley
    National Laboratory have confirmed that more
    energy is being absorbed from the Sun than is
    emitted back to space, throwing the Earth's
    energy "out of balance" and warming the planet.
    ( Using satellites, data from buoys and computer
    models . )

5
Albedo a measure of how much solar energy is
absorbed by a surface
Reds and oranges show high albedo where the
surface is very absorbing radiation, while blues
and purples show surfaces that reflect more light.
6
Insolation Varies
  • Normal variations in the suns radiation
  • Known from ice core data

7
  • Q Could reduced reflectivity, rather than
    greenhouse gases, explain the Earth's warming?  
  • A Scientists have concluded after monitoring
    the Earth's reflectivity for decades, changes in
    our planet's reflectivity can't explain the
    warming trend we currently are experiencing

8
Milankovitch Cycles
  • Earths rotation and revolution combine to make
    the planet wobble in its orbit
  • This changes the position of the earth and
    affects seasonal temperatures and albedo
  • Such changes are believed to be principally
    responsible for the waxing and waning of glacial
    periods (100,000 yr. time spans) and normal
    climate cycles (20,000 40,000 year cycles)

9
  • Milankovitch cycles have tremendous value as a
    theory to explain ice-ages and long-term changes
    in the climate
  • they are unlikely to have very much impact on the
    decade-century timescale of global warming
    phenomenon
  • http//apollo.lsc.vsc.edu/classes/met130/notes/cha
    pter16/graphics/71_Orbital_Fluctuations/A_71.swf

10
Volcanoes and Dust
  • Volcanic dust blasted into the atmosphere causes
    temporary cooling. The amount of cooling depends
    on the amount of dust put into the air, and the
    duration of the cooling depends on the size of
    the dust particles

11
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12
  • dust thrown up by windstorms or human activity
    can affect the passage of heat and light through
    the air

13
ENSO
  • Climate variability are smaller-scale changes
    in the energy balance
  • Climate change may affect the intensity and
    frequency of ENSO events

14
Ocean Currents
Because freshwater is less dense than seawater,
increased precipitation, melting of polar
glaciers and ice caps could block the system by
reducing the amount of cold water that sinks
downwards. Models currently predict a 25 slow
down of the Gulf Stream.
15
  • There is no doubt that climate has natural
    variability over long periods of time

16
HOWEVER The most significant factor attributing
to global warming and climate change at this time
is believed to be the rising amount of greenhouse
gases, such as carbon dioxide and methane, in the
atmosphere...
17
Greenhouse Effect Natural Processthat
moderates our climate and makes life possible on
earth.
18
  • The Effect of Carbon Dioxide on Warming
  • The greenhouse effect refers to circumstances
    where the short wavelengths of visible light from
    the sun pass through the atmosphere and are
    absorbed by the earths surface.
  • The longer wavelengths of the infrared
    re-radiation from the heated surfaces are unable
    to pass through the atmosphere.
  • The trapping of the long wavelength radiation
    leads to more heating and a higher resultant
    temperature.
  • Carbon dioxide strongly absorbs infrared
    radiation, so the greater the carbon dioxide the
    more infrared absorption.
  • This leads to greater heat retention in the
    atmosphere.

19
Human Impact on the Greenhouse Effect
20
  • These are sketches of the graphs produced in the
    IPCC 2007 report of the increase in key
    greenhouse gases. They make clear that most of
    the increase of the last thousand years has
    occurred in the past 200 years.

21
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22
From 1980 to the end of the 21st century,
temperatures are projected to increase by 1.8C
to 4.0C.
23
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24
IPCC Conclusions
  • Current warming trends are unequivocal. It is
    very likely that greenhouse gases released by
    human activities are responsible for most of the
    warming observed in the past fifty years. The
    warming is projected to continue and to increase
    over the course of the 21st century and beyond.
  • Climate change already has a measurable impact on
    many natural and human systems snow and ice are
    melting and frozen ground is thawing,
    hydrological and biological systems are changing
    and in some cases being disrupted, migrations are
    starting earlier, and species' geographic ranges
    are shifting towards the poles. Effects are
    projected to increase in the future and to be
    more severe with greater increases in
    temperature. Adaptation measures are already
    being implemented, and will be essential in order
    to address the projected consequences. There is,
    however, a limit to adaptation mitigation
    measures will also be needed in order to reduce
    the severity of impacts. (NOTE difficult to
    separate natural variability from climate change
    effects, more research needed).
  • Mitigation measures that aim to reduce greenhouse
    gas emissions can help avoid, reduce or delay
    many impacts of climate change. Policy
    instruments could create incentives for producers
    and consumers to significantly invest in
    products, technologies and processes which emit
    less greenhouse gases. Without new mitigation
    policies, global greenhouse gas emissions will
    continue to grow over the coming decades and
    beyond. Rapid world-wide investments and
    deployment of mitigation technologies, as well as
    research into new energy sources will be
    necessary to achieve a stabilization of the
    concentration of greenhouse gases in the
    atmosphere.
  • Additional research addressing gaps in knowledge
    would further reduce uncertainties and thus
    facilitate decision-making related to climate
    change.

25
ADAPTATION and MITIGATION
  • ADAPT coastal defenses, government response to
    heat waves and flooding, technology solutions,
    modify consumption habits
  • MITIGATE reduce greenhouse gas emission
  • Kyoto (international cooperation) individual
    government policies to reduce emissions
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