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Global Warming Debate

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Title: Global Warming Debate


1
Global Warming Debate
2
QA Climate change
  • Accelerating ice-melt may be a sign of global
    climate change
  • The Earth is getting warmer. Scientists predict
    increasing droughts, floods and extreme weather
    and say there is growing evidence that human
    activities are to blame.
  • BBC News Online looks at the key questions behind
    climate change and global warming.

http//news.bbc.co.uk/1/hi/sci/tech/3928017.stm
3
  • What is climate change?
  • The planet's climate is constantly changing. The
    global average temperature is currently in the
    region of 15C. Geological and other evidence
    suggests that, in the past, this average may have
    been as high as 27C and as low as 7C.
  • But scientists are concerned that the natural
    fluctuation has been overtaken by a rapid
    human-induced warming that has serious
    implications for the stability of the climate on
    which much life on the planet depends.

4
  • What is the "greenhouse effect"?
  • The "greenhouse effect" refers to the role played
    by a layer of gases which effectively trap the
    heat from the Sun in the Earth's atmosphere.
    Without them, the planet would be too cold to
    sustain life as we know it.
  • These gases include carbon dioxide, methane and
    nitrous oxide, which are released by modern
    industry, agriculture and the burning of fossil
    fuels.
  • Their concentration in the atmosphere is
    increasing - the concentration of carbon dioxide
    has risen by more than 30 since 1800.
  • The majority of scientists accept the theory that
    an increase in these gases will cause a rise in
    the Earth's temperature.

5
  • What is the evidence of warming?
  • Temperature records go back to the late 19th
    Century and show that global average temperature
    increased by about 0.6C in the 20th Century.
  • Sea levels have risen 10 - 20cm - thought to be
    due mainly to the expansion of warming oceans.
  • Most of the recorded non-polar glaciers are in
    retreat and records show Arctic sea-ice has
    thinned by 40 in recent decades in summer and
    autumn.
  • There are anomalies however - parts of the
    Antarctic appear to be getting colder, and there
    are discrepancies between trends in surface
    temperatures and those in the troposphere.

6
  • How much will temperatures rise?
  • If nothing is done to reduce emissions, current
    climate models predict a global temperature
    increase of 1.4 - 5.8C by 2100.
  • To put this in context, global temperatures are
    thought to have fluctuated by only one degree
    Celsius since the dawn of human civilisation.
  • Even if we cut greenhouse gas emissions
    dramatically now, scientists say the effects
    would continue because parts of the climate
    system, particularly large bodies of water and
    ice, can take hundreds of years to respond to
    changes in temperature.
  • Some scientists say it is possible that we have
    already irrevocably committed the Greenland ice
    sheet to melting.
  • This would take centuries - if not millennia -
    but would cause an estimated seven metre rise in
    sea level.

7
  • How will the weather change?
  • Globally, we can expect more extreme weather
    events, with heat waves becoming hotter and more
    frequent.
  • Scientists predict more rainfall overall, but say
    the risk of drought in inland areas during hot
    summers will increase.
  • More flooding is expected from storms and rising
    sea levels.
  • There are, however, likely to be very strong
    regional variations in these patterns, and these
    are difficult to predict.

8
  • What will the effects be?
  • The potential impact is huge, with predicted
    freshwater shortages, sweeping changes in food
    production conditions, and increases in deaths
    from floods, storms, heat waves and droughts.
  • Poorer countries, which are least equipped to
    deal with rapid change, will suffer most.
  • Plant and animal extinctions are predicted as
    habitats change faster than species can adapt,
    and the World Health Organisation has warned that
    the health of millions could be threatened by
    increases in malaria, water-borne disease and
    malnutrition.

9
  • What don't we know?
  • We don't know exactly how much warming is caused
    by human activities or what the knock-on effects
    of the warming will be.
  • Global warming will cause some changes which will
    speed up further warming, such as the release of
    large quantities of the greenhouse gas methane as
    permafrost melts.
  • Other factors may mitigate warming - such as
    plants taking more CO2 from the atmosphere as
    their growth rate is increased by warmer
    conditions.
  • Scientists are sure how the complex balance
    between these positive and negative feedback
    effects will play out.

10
  • What about the sceptics?
  • Most global warming sceptics do not deny that the
    world is getting warmer, but they do doubt that
    human activity is the cause.
  • Some say the changes now being witnessed are not
    extraordinary - similar, rapid changes can be
    seen at other times in Earth's history when
    humans did not exist.
  • Some point to the Sun's present high activity as
    the prime influence on recent temperature trends.
  • Nevertheless, there is a growing scientific
    consensus that, even on top of the natural
    variability of the climate, something out of the
    ordinary is happening and humans are to blame.

11
  • What is the international community doing?
  • An international agreement, the Kyoto Protocol,
    commits industrialised countries to specific
    targets for reducing their greenhouse gas
    emissions.
  • It must be ratified by a certain number of
    countries before it becomes binding. The protocol
    suffered a huge blow when the US - responsible
    for a quarter of global emissions - pulled out in
    2001.
  • The agreement will now only come into force if
    Russia ratifies it.
  • While many countries have taken steps to reduce
    their emissions, the Kyoto targets are just a
    fraction of the emissions reductions thought
    necessary to slow global warming significantly.

12
  • History of Global Warming
  • NOW with Bill Moyers

13
  • Debating Global Warming
  • NOW with Bill Moyers

14
Skeptical of global warming fears In favor of a global effort to reverse climate change
"Environmentalists have viewed climate change as a catastrophe necessitating immediate and major steps to head off or mitigate. Whether global warming will occur is uncertain. Although temperature data until now could reflect a warming planet, they are also consistent with normal fluctuations in weather. From a scientific viewpoint the evidence for global warming must be 'not proven.'" - Thomas Gale Moore, Hoover Institute "Even if the theory of global warming is wrong, we will be doing the right thing in terms of economic policy and environmental policy." - Tim Wirth, former U.S. Senator from Colorado



Source http//www.pbs.org/now/science/climatedeba
te.html
15
Skeptical of global warming fears In favor of a global effort to reverse climate change
"I believe that it is fair to say that the people once labeled as 'a small band of skeptics' those who championed the position that warming would be modest and primarily in the coldest air-masses have won the day. Many of these same scientists are now forming a new environmental paradigm. It is that the concept of 'fragile earth' must be abandoned. And it asks the impertinent question since when is everything that man does to the planet necessarily bad?" - Patrick J. Michaels, CATO Institute Congressional Testimony "In the United Stateswe have to first convince the American people and the Congress that the climate problem is real." - former President Bill Clinton, 1997 address to the United Nations


Source http//www.pbs.org/now/science/climatedeba
te.html
16
Skeptical of global warming fears In favor of a global effort to reverse climate change
"Scientists who want to attract attention to themselves, who want to attract great funding to themselves, have to (find a) way to scare the publicand this you can achieve only by making things bigger and more dangerous than they really are." - Petr Chylek, Professor of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia "People are changing the climate that made life on earth possible and the results are disastrous - extreme weather events, such as droughts and floods, disruption of water supplies, melting Polar regions, rising sea levels, loss of coral reefs and much more. It is not too late to slow global warming and avoid the climate catastrophe that scientists predict. The solutions already exist. Renewable energy sources such as wind and solar offer abundant clean energy that is safe for the environment and good for the economy." - Greenpeace
Source http//www.pbs.org/now/science/climatedeba
te.html
17
Skeptical of global warming fears In favor of a global effort to reverse climate change
"The Little Ice Age and the Medieval Warming that preceded it from 950 to 1300 AD stand out in every temperature record as the major weather events of the last 1,000 years, and they're a hefty problem for global warming advocates. If the world was warmer in 1200 AD than today, and far colder in the year 1400, why would we blame current temperatures trends on auto exhausts?" - Dennis Avery, Center for Global Food Issues "Emissions of greenhouse gases and aerosols due to human activities continue to alter the atmosphere in ways that are expected to affect the climate." - Summary for Policymakers, A Report of Working Group 1 of the Intergovernmental Panel on Climate Change
Source http//www.pbs.org/now/science/climatedeba
te.html
18
  • BBC Global warning? program

19
CLIMATE WARSProgramme 1 The scienceTwo
Harvard astronomers became the toast of
Washington as they attacked the consensus view
that global warming is a problem, and argued that
humanity has survived similar episodes as
recently as the Middle Ages. Gerry Northam
charts the genesis and fate of this research, how
it has been taken up by Washington conservatives,
and the highly enflamed debate that followed.
20
CLIMATE WARSProgramme 2 The actionThe Kyoto
protocol was meant to be the first step towards
stopping and reversing global warming, but when
the US declared it would have nothing to do with
it in 2001, the treaty looked dead. That's what
the US administration argued at the time. But
with Russia perhaps on the brink of signing the
protocol, despite a fog of words suggesting the
opposite, and with the rest of the industrialised
world and even individual states in the USA
moving ahead with climate measures, it may be
that Washington gets left behind.
21
  • The Kyoto Agreement BBC site

22
  • Extreme Weather
  • Increasing temperatures means the World is likely
    to see less frosty days and cold spells, but we
    are expected to experience an increase in heat
    waves and hot spells
  • Greater risk of drought in summer in continental
    areas
  • The greatest warming over the next 100 years is
    expected to be at higher latitudes and the
    smallest amount of warming, in the tropics
  • Increase in extreme precipitation events
  • Hurricanes likely to be more intense in some
    parts of the World due to more rainfall and more
    intense winds
  • Its not clear what will happen with
    thunderstorms or tornadoes
  • An intensification of the Asian summer monsoon is
    expected
  • There is no evidence for changes in the
    frequency, intensity or location of tropical
    storms
  • Storm surges are expected to increase in
    frequency and in the UK the south east coast is
    expected to see the largest surges at around 1.2m
    higher than we have now (this is in the 2080s
    with the "medium high emissions" scenario)
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