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Climate
change is “a change of climate which is attributed directly or indirectly
to human activity that alters the composition of the global atmosphere and
which is in addition to natural climate variability observed over
comparable time periods.” (from United Nation’s Framework Convention on
Climate Change) |
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Observed warming |
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0.6°C
in the last 100 years. |
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Tectonic Scale |
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Cooling by 0.00002°C within 100 years |
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Orbital Scale |
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Cooling by 0.02°C within 100 years |
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Millennial Scale |
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Uncertain, but probably on the order of 0.02°C (such as the net
cooling into the Little Ice Age) |
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Solar Activities |
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May
cause 0.2°C warming |
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How do
we weight the possible harm of our actions against the advantage of
economic growth? |
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è Policy makers want scientists to make
precise predictions of the timing and magnitude of the future global
warming. |
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YES. Our
understandings of the climate system and the recent advancements in
computer climate modeling have allowed us to predict the future global
warming and its impacts. |
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But with uncertainties. There are still
significant uncertainties in predicting the timing and magnitude of the
warming. |
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Earth’s climate is determined by enormously
complex interactions among the atmosphere, ocean, land surface, vegetation,
ice ….. |
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The complexity of the Earth climate system leads
to inevitable uncertainties in scientific predictions of the impacts of
human activities. |
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In an
effort to study the predictability of weather, Edward Lorenz (a meteorology
professor at MIT) started the study of “chaos” systems. |
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The weather/climate system is a nonlinear
system. A small change in its initial condition can be amplified to a huge
disproportionate effect on the whole system. |
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For example, the small change caused by the
flapping of the butterfly's wings in the Far East may causes massive
changes in the eventual overall behavior of the storm in the North America. |
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It is
important to accept that fact that “..although accurate predictions are, in
principle, possible on the basis of the laws of physics, such forecasts may
be impossible in practice..” because the complexity of our climate system. |
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Rather
than implement comprehensive programs that decree a rigid course of
action to reach grand and final
solution, |
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We
should promote adaptive programs whose evolution is determined by the
results of these programs and by the new scientific results that become
available. |
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In 1987,
the world agreed in the Montreal Protocol that each country would limit its
production of the chlorofluorocarbons (CFCs) that contribute to the
depletion of the ozone hole. |
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This
decision was made before clear evidence
that CFCs are harmful to the ozone layer. |
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The
regulations were agreed in subject to periodic reviews to accommodate new
scientific results. |
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A
gardener finds that his pond has one lily pad on a certain day, two the
next day, four the subsequent day and so on. After 100 days the pond is
completely filled with lily pads. On what day was the pond half full? |
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ANSWER: Day 99 |
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Suppose
the gardener, once he realizes what is happening, quickly enlarge the pond
to twice its size. On what day will the new pond be completely filled? |
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ANSWER: Day 101 |
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Is our
global warming problem close to Day 1 or Day 100? |
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In stead
of waiting for a precise answer to end this debate, it is more important to
recognize the explosive-growth nature of the global warming problem. |
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It is
wiser to act sooner than later. |
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The Gaia hypothesis argues that life itself has
been responsible for regulating Earth’s climate. |
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This hypothesis states that the biosphere acts
as an organism that maintains conditions that are favor to life. |
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When the intensity of sunshine increase |
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è increase
global temperature |
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è favor
the growth of daisy |
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è increase
the number of white daisies |
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è daisies
reflect more sunshine back to space |
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è global
temperatures stop to increase |
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è daisy
acts as a thermostat to control global temperature |
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è support
the Gaia hypothesis. |
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However,
if there is threshold temperature beyond which the white daisy would die,
then the Gaia hypothesis won’t work. |
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When the intensity of sunshine increase |
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è increase
global temperature TOO MUCH |
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è decrease
the number of white daisies |
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è daisies
reflect less sunshine back to space |
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è global
temperatures continue to increase |
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è white
daisies distinct |
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è against the
Gaia hypothesis. |
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There is no doubt that life can affect global
climate. |
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But it is controversy whether the biosphere is
capable of controlling the global environment to its own benefit. |
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Our
planet may seem robust from the perspective of the entire biosphere, but it
can appear fragile from the perspective of individual species, specially
for us. |
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Uncertainties in science are inevitable. |
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We need
to familiarize ourselves with the processes that determine the climate of
this planet and the sensitivity of these processes to perturbations. |
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Over
tens of thousands of years, we are unlikely to do great harm to our planet
as a whole. |
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We can, however, cause inconvenience to
ourselves in the next several decades by continually perturbing the global
climate. |
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