EESA01 - EESA01
Lecture
10
 Global
Climate
Change
 November
21,
2011
 Lecture
10
–
Global
Climate
Change
 1


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Unformatted text preview: EESA01
Lecture
10
 Global
Climate
Change
 November
21,
2011
 Lecture
10
–
Global
Climate
Change
 1
 The
Greenhouse
Effect
 Lecture
10
–
Global
Climate
Change
 2
 What
We
Know:
Greenhouse
 Gases
 •  Most greenhouse gases are both naturally and human-generated • Human activities have increased GHG emissions over past 300 years •  This has enhanced the Greenhouse Effect •  Different gases have different global warming potentials Lecture
10
–
Global
Climate
Change
 3
 Sources
of
CO2
 •  •  •  •  •  •  The
decay
of
organic
maJer
(respiraMon;
 decomposiMon)
 Breathing
 Burning
anything
carbon‐based
 Volcanic
erupMons
 Natural
sources
outweigh
anthropogenic
sources,
but
 it
is
human
acMvity
that
has
increased
the
overall
 pool
of
CO2
in
the
atmosphere

removal
from
 lithosphere
and
into
atmosphere
(shiSed
fluxes)
 Increase
from
280
ppm
in
1700’s
to
~390
ppm
today
 Lecture
10
–
Global
Climate
Change
 4
 Recent
Trends
 Figure 14.12 Lecture
10
–
Global
Climate
Change
 5
 Feedbacks
are
Important
 •  Possible
posiMve
feedbacks:

 1.  Increased
temperatures
result
in
increased
evaporaMon,
 which
increases
water
vapour
(GHG),
which
increases
 temperature…
 2.  Increased
temperatures
results
in
increased
soil
gas
 emissions,
which
could
increase
temperatures…
 3.  Aerosols?

White,
black,
or
haze…
 •  Possible
negaMve
feedbacks:

 1.  Increased
temperatures
result
in
increased
evaporaMon,
 which
increases
cloud
cover,
which
decreases
temperature
 2.  Increased
temperatures
and
weJer
condiMons
promote
soil
 formaMon,
sequestering
more
carbon
 Lecture
10
–
Global
Climate
Change
 6
 RadiaMve
Forcing
is
Key
Measure
 •  •  •  •  A
measure
of
the
 influence
of
a
climaMc
 factor
(ice,
albedo,
etc)
 has
in
altering
net
 energy
of
the
Earth‐ atmosphere
 PosiMve
forcing
=
 warmer
 NegaMve
forcing
=
 cooler
 Today:
+1.6
W
m‐2
 compared
to
pre‐ industrial
 Lecture
10
–
Global
Climate
Change
 Variations in solar input ~ 0.12 W m-2 7
 How
do
We
Measure
Past
 Temperatures
and
Predict
Future
Ones?
 •  •  •  •  •  We
only
have
ACTUAL
measurements
of
temperature
 and
other
climaMc
factors
(rainfall)
for
a
few
hundred
 years
at
best
 There
are
several
methods
for
figuring
out
 paleoclimate
by
using
proxies
 Tree‐rings
and
coral
growth
rings
(provide
annual
 Mmeline)
for
up
to
couple
thousand
years
 Pollen
analysis
in
sediment
 Trapped
air
bubbles
in
cores
of
ice
sheets/glaciers
 –  Have
taken
our
knowledge
as
far
back
as
740,000
ybp
 Lecture
10
–
Global
Climate
Change
 8
 Future:
Climate
Modeling
 •  •  •  Coupled
general
 circulaMon
models
 (GCMs)
 “Coupling”
is
between
 climate
influences
of
 atmosphere
and
oceans
 Combine
what
we
know,
 including
feedbacks,
and 
 run
different
scenarios
 related
to
past
and
 future
CO2
 concentraMon
 Lecture
10
–
Global
Climate
Change
 9
 Lecture
10
–
Global
Climate
Change
 10
 Natural
Climate
Variability
 1.  Milankovitch
Cycles
alter
solar
radiaMon
hipng
Earth
 –  1.  2.  3.  Partly
responsible
for
long‐term
climate/glacial
cycles
 Wobble
(Precession):
19,000‐23,000
year
cycle
 Tilt:
3°
shiS
on
41,000
year
cycle
 Orbit
variaMon:
100,000
year
cycle
 2.  Solar
output:
11‐year
sunspot
cycle;
responsible
 forcing
<0.12
W
m‐2
 Lecture
10
–
Global
Climate
Change
 11
 Milankovitch
Cycles
 Figure 14.5 Lecture
10
–
Global
Climate
Change
 12
 So…Are
We
Responsible
For
This?
 •  •  Very
clear
that
the
increase
in
greenhouse
gases
is
 largely
due
to
human
acMviMes
(combusMon
of
fossil
 fuels,
land
use
changes)
 World’s
experts
are
~90%
sure
(remember;
no
 absolute
truth
in
science!)
that
increases
in
global
 temperature
are
a
result
of
increased
greenhouse
gas
 concentraMons
in
the
atmosphere
 “The
scienMfic
understanding
of
climate
change
is
now
sufficiently
clear
to 
 jusMfy
naMons
taking
prompt
acMon.

It
is
vital
that
all
naMons
idenMfy
cost‐ effecMve
 steps
 that
 they
 can
 take
 now,
 to
 contribute
 to
 substanMal
 and 
 long‐term
reducMon
in
net
global
greenhouse
gas
emissions
…
A
lack
of
full 
 scienMfic
certainty
about
some
aspects
of
climate
change
is
not
a
reason 
 for
delaying
an
immediate
response
that
will,
at
a
reasonable
cost,
prevent 
 dangerous
anthropogenic
interference
with
the
climate
system.”
 Lecture
10
–
Global
Climate
Change
 13
 Some
Possible
Climate
Change
 Effects
 •  Increased
Temperatures
(especially
the
ArcMc):

 •  Glacier
MelMng
 Lecture
10
–
Global
Climate
Change
 14
 Some
Possible
Climate
Change
 Effects
 Sea Level Rise Lecture
10
–
Global
Climate
Change
 Ice Cap Melting 15
 Some
Possible
Climate
Change
 Effects
 •  Ecosystem
AlteraMon:

 Lecture
10
–
Global
Climate
Change
 16
 •  A1:

 –  –  –  •  Similar
to
above,
but
more
rapid
change
in
economy
toward
 service‐
and
informaMon‐based
society
 B2:

 –  –  •  Rapid
economic
growth
 Peak
in
global
populaMon
around
2050
 Rapid
introducMon
of
new
and
more
efficient
technologies
 B1:

 –  •  IPCC
Scenarios
 Intermediate
populaMon
and
economic
growth
 Emphasis
on
local
economic,
social,
environmental
 soluMons
 A2:

 –  –  High
populaMon
growth
and
slow
economic
development
 Slow
acceptance
of
lower‐emission
energy
technology
 Lecture
10
–
Global
Climate
Change
 17
 Future
Depends
on
Us
 Lecture
10
–
Global
Climate
Change
 18
 Modeling
in
Climate
Science
 •  •  •  •  There
is
a
TONNE
of
misinformaMon
out
there
 (Internet,
media,
lobbyists,
etc).

 You
need
to
take
the
best
scienMfic
informaMon
 available
to
you
and
then
put
your
criMcal
thinking
 skills
into
hyper‐drive.

 One
of
the
main
issues
that
people
someMmes
 have
is
to
what
extent
we
can
“rely
on”
models
for
 predictability.
 hJp://www.youtube.com/watch? v=D6Un69RMNSw
 Lecture
10
–
Air
PolluMon
and
Climate
Change
 19
 SoluMons:
MiMgaMon
vs
AdaptaMon
 •  Mi/ga/on:
looking
for
ways
of
alleviaMng/solving
a
 problem
 –  •  Adapta/on:
accept
situaMon
and
look
into
ways
to
 minimize
impact
on
us
 –  •  For
this,
it
would
largely
involve
reducing
and
eliminaMng
 greenhouse
gas
emissions
and
stopping
landuse
effects
on
 carbon
sequestraMon
(i.e.,
improve
agricultural
pracMces
 and
halt
deforestaMon)
 Includes
things
like
beJer
flood
protecMon,
more
drought resistant
crops,
more
engineering
in
general
 Although
adaptaMon
is
a
bit
of
a
“cop‐out”,
it
will
be
 necessary
to
take
acMon
on
this
as
well
because
we
 ARE
going
to
see
effects
even
if
we
eliminated
 emissions
tomorrow
(lag
effect)
 Lecture
10
–
Global
Climate
Change
 20
 Current
Government
Strategy
 •  •  •  •  •  Tried
once
in
the
90’s
(1992),
to
form
a
“voluntary”
 global
treaty
on
climate
change
(UN
Framework
 ConvenMon
on
Climate
Change),
which
failed
 miserably
 Led
to
the
Kyoto
Protocol
(started
1997),
which
 REQUIRES
all
signing
naMons
to
reduce
emissions
 Required
naMons
to
reduce
emissions
to
levels
below
 those
of
1990
by
2012
 Canada
raMfied
in
2002;
treaty
took
effect
in
2005
aSer
 Russia
signed
 USA
refused
to
raMfy
mostly
because
it
disagreed
with
 easier
treatment
of
industrializing
naMons
(China,
India)
 Lecture
10
–
Global
Climate
Change
 21
 How’s
it
Going?
 KYOTO HAS FAILED AS WELL! ACTION IS STILL NEEDED! Lecture
10
–
Global
Climate
Change
 22
 2009
Copenhagen
Summit
 •  •  •  •  •  Really
provided
very
liJle
addiMonal
“teeth”
to
what
was
 already
going
on.
 Legal
binding
of
the
accord
not
at
all
clear.
 Basically
a
conMnuaMon
of
the
Kyoto
Accord,
which
 expires
next
year.

 Canada
commiJed
to
reducing
CO2
emissions
by
17%
by
 2020,
compared
to
2005
levels
(same
commitment
as
 USA).

 Canada
won
the
“Colossal
Fossil”
of
the
year
award
(mock
 award
not
associated
with
summit)
for
third
year
in
a
row.
 –  For
essenMally
having
done
nothing
meaningful
in
the
way
of
 fighMng
climate
change
by
reducing
emissions
 Lecture
10
–
Global
Climate
Change
 23
 “Cap
and
Trade”
and
“Carbon
Offsets”
 •  •  •  •  •  •  Financial
insMtuMons
have
picked
up
on
the
economic
 “opportuniMes”
related
to
global
climate
change
 Cap
and
Trade
allows
for
industry
who
reduce
emissions
 below
a
threshold
to
SELL
their
GHG
emission
reducMons
 to
other
companies
who
pollute
more
 There
are
actual
“exchanges”
for
this,
eg.
Chicago
Climate
 Exchange
 Carbon
Offsets
allow
payment
to
someone
else
to
offset
 emissions,
eg.
paying
for
a
reforestaMon
project
that
may
 sequester
as
much
carbon
as
a
coal‐fired
electricity
facility 
 generates
 So,
if
you
have
the
$$,
you
don’t
have
to
change
your
 lifestyle/business;
is
this
a
great
idea?
 Currently
not
parMcularly
transparent
or
enforceable
 Lecture
10
–
Global
Climate
Change
 24
 What
does
Wobble
have
to
do
with
it?
 1.  What
is
wobble
anyway?

 –  “Precession”
is
the
wobbly
moMon
that
a
rotaMng
body
has
 when
subjected
to
torque

this
can
change
the
axis
of
 rotaMon
 2.  Impact
on
climate:
 –  –  –  The
wobbling
causes
the
change
in
Mlt
 With
less
Mlt,
cooler
high‐laMtude
summers
may
feed
back
to
a
cooler
 climate
wherein
a
posiMve
feedback
of
snow
and
ice
accumulaMon
begins
 Has
effect
on
where
Earth
is
“poinMng”
and
thus
impacts
variability
 among
seasons
in
the
northern
and
southern
hemispheres
 Lecture
10
–
Global
Climate
Change
 25
 ...
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This note was uploaded on 02/29/2012 for the course ENVIRONMEN eesa01 taught by Professor Mitchel during the Fall '11 term at University of Toronto- Toronto.

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