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Global Warming Debate
Q&A: 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.
• 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.
• 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
• 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
• How much will temperatures rise?
• If nothing is done to reduce emissions, current climate
models predict a global temperature increase of 1.4 5.8°C 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
• This would take centuries - if not millennia - but would
cause an estimated seven metre rise in sea level.
• 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
• More flooding is expected from storms and rising sea
• There are, however, likely to be very strong regional
variations in these patterns, and these are difficult to
• 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.
• 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
• 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
• 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.
• 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.
• History of Global Warming
NOW with Bill Moyers
• Debating Global Warming
NOW with Bill Moyers
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
"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
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
"In the United States…we 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
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 public…and 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
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
- 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
• BBC Global warning? program
Programme 1: The science
Two 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.
Programme 2: The action
The 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
• The Kyoto Agreement BBC site
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
• It’s 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 2080’s with the "medium high
emissions" scenario)