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Transcript
Climate Change
The consensus of scientific opinion is that the
climate is changing rapidly and that those changes
are being forced by human activities: industrial,
forestry, personal lifestyle choices, and agricultural.
This course does not include a debate about the
pros and cons of this position because this is a
science based, employment preparation course. The
political and economic pressures created by climate
change will impact the work of and skills required of
technical workers. Employers will be forced to
change energy use methods either through
legislation or public opinion. Therefore technicians
will need to improve energy efficiency and
sustainability of their workplaces. They will also
have to advise about adopting alternative energy
sources then troubleshoot, maintain, and repair
those systems.
The goal with this section is to understand the
science behind climate change theory. Note theory
is used here in its scientific meaning.)
1
Climate change = global warming = climate
instability
Throughout the earth’s history (deep time) climate
has shifted many times. The evidence is found in
geological research and ice core analysis. Often,
though not always climate shifts were linked to
increases and declines in CO2 levels. High CO2 =
hotter temperatures. Other climate changes were
related to the earth's orbit and/or the tilt of the
earth. So climate is not "set" or stable. It changes
usually over long time frames, but occasionally
dramatically fast.
Temperatures and CO2derived tree rings, coral,
ice cores, lake sediments tell us that pre
industrial CO2 levels were about 280 ppm. Now
they are about 386 ppm, and this increase
coincides with the increased combustion of
fossil fuels that began with the industrial
revolution.
Deep time studies: “This confirms the general
notion that substantial greenhouse warming is
2
the expected consequences of a buildup of
atmospheric CO2."
Deep time is difficulty to understand for us
short-lived humans. Deep time = a damn long
time, so long that humans can not understand
its ramifications. During its history earth has
been a ball of molten rock, completely ice
covered, and mostly tropical.
One visualization of the immensity of deep time
is this:
The distance from an English king's nose to the
tip of his outstretched hand is the original
standard for the English yard. Imagine deep
time as that king extending his arm. One stroke
of a nail file on his middle finger erases all of
human history.
The only constant in life is change
Intergovernmental Panel on Climate Change
(IPCC)
3
There are two basic types of climate forcers
(external) sun, volcanic eruptions, earth’s orbit,
(internal) human activities (anthropogenic)
Anthropogenic = carbon dioxide CO2, methane
CH4, nitrous oxides N20, aerosols (small
particles tend to reflect solar radiation), water
vapor
Our Earth is warmed by absorbed solar energy.
The warm earth radiates heat away into frigid
space and this heat energy must pass upward
through the atmosphere. As it passes through
the atmosphere some of that heat is absorbed
by the greenhouse gasses and they warm the
surrounding atmosphere. The warmer
atmosphere radiates some heat to space, but
some returns back to the earth. Today there is
less heat being radiated than absorbed so the
earth gets gradually warmer.
BUT, climate is very, very complicated. For
example increasing CO2 leads to global
warming which increases the evaporation of
water which helps to trap radiated heat and/or
the increased water vapor creates more low
4
clouds which trap heat, but the tops of the
clouds reflect solar radiation.
“The average rate of global warming over the
full 20th century was slightly less than 0.1C per
decade, but in the past few decades the
warming rate has nearly doubled to about 0.2 C
per decade.”
We would like science to be precise and give
exact answers like simple high school chemistry
experiments, but in reality science is always
modifying its knowledge. New assertions are
reported and challenged by other scientists, or
experiments are repeated with different results,
or observations are reinterpreted. Science is a
"best educated guess", but that is better than
an uneducated feeling.
Evidence for the consequences of climate
change:
Increasing regional droughts
The warmest years in 500 years have been
recorded in the past decade
Warmer days and nights all over the world
5
More extreme weather
Warmer ocean surface temps
Mountain snow and glaciers are melting. Mt
Hood climbing season is getting shorter. Mt
Kilimanjaro has had permanent ice field for
12000 years and it has melted back
dramatically since 1912
Ocean levels are rising
The theory of global warming predicts these
results and the scientific records indicate that
this is occurring.
The IPCC, 2007 report projections range fro
99% certainty of warmer days and nights, to
90% certainty of more frequent heat waves and
heavy rains, to a 66% likelihood of glacier
melting, to a 33-59% chance of the West
Antarctic ice sheet melting, to a 10% probability
of the ocean currents stopping with catastrophic
climatic changes including super storms.
This very unlikely event is the premise of the
movie "Day After Tomorrow"
6
There will be climate change, and no one is
sure how much, but it could be bad and that is
the worry.
In addition many of the greenhouse gasses
remain in the atmosphere for centuries so the
long-term consequences are difficult to predict.
Climate models extremely complex, but they
appear accurate when applied to past changes,
so they are the best we have now.
“Climate sensitivity defines the amount of
warming (in degrees Celsius) that we can
expect to occur when there is a change in the
factors that control climate." It is possible that
there could be gradual change or sudden
catastrophic changes since we are adding so
much green house gas into the atmosphere so
quickly. For example temperature rises could
be anywhere from 1.5 to 9°C with anything
above 5-6°C being very dangerous, possibly
fatal.
Some, a great deal of the CO2 can be
absorbed by the oceans and plants, but there
are limits and this could mean more warming.
7
It is possible that the oceans could warm
enough to release large amounts of methane
"burpes of death" and it goes on and on….
Impacts of global warming
Sea level rise floods low coastal lands and
islands
Loss of ecosystems like wetlands, coral reefs (
Species extinction 20-30% extinct with 2°C –
40-70% with 4°C temperature rise.
Floods and droughts
Diminished fresh water, evaporated and
polluted
Famine
Disease
Deforestation due to fires
Mass migrations – wars
Polar meltdown = rise in ocean level,
permafrost thaw with release of methane
8
What to do
Adapt or mitigate
adapt = build dykes etc
mitigate = reduce CO2 and other greenhouse
gasses
Costs = pay me now or pay me later. 1-2%
GDP now, 20% later
Who pays the rich nations, the poor nations?
Build dykes, costly & time consuming and
evacuating low lying islands is costly
Water management = “no regrets” changes for
example use less water
Agriculture food price increases of between 10
– 40 % depending on the level of temp rise
WHAT TO DO?
Technological fixes are at hand – will we
(society) make the changes which change our
economy and lifestyles?
9
As technical workers you will be expected to
improve energy efficiency and help with
decisions regarding the use and adoption of
alternative energy technologies.
The big unknown is that countries like China,
India, and other Asian nations are rapidly
modernizing and their green house gas
emissions to rising rapidly, just as those in the
more developed world have since 1750.
Good luck!
Denis Green
10