Transcript 14-July-2011

In the name of GOD
The Chemistry of Climate
14-July-2011
The Chemistry of Climate
When there is a thing, there is chemistry…
H
He
Relative log(Abundance, Universe)
C
O
N
Ne
F
Li Mg
Na
Be
Al
Fe
Ca
K
Ti
V
Sc
Rb
Sr
Y
Cr
Zr
Mn
Mo
Nb
Ni
Co
Cu
Zn
B Si
Ga
Ru
Rh
Pd
Ag
Cd
In
Os
Ir
Pt
Au
Hg
Tl
Tc
Cs
Fr
Ba
Ra
La
Hf
W
Ta
Re
S
P
Ge
As
Sn
Sb
Pb
Ar
Cl
Se
Br
Kr
Te
I
Xe
Bi
Po
At
Rn
Ac
Ce
Th
Pr
Pa
Nd
Pm
U
Np
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
Yb
No
Lu
Lr
14-July-2011
The Chemistry of Climate
What about the Earth?
Relative log(Abundance, Earth)
O
Ca
K
Rb
V
Ba
Zr
Y
La
Ta
Ra
Ac
Ce
Pr
Ni
Co
Cl
Zn
Cu
Ne
Ga
Ge As
Br
Ar
I
Kr
Se
Mo
Ru
Tc
W
Nd
Th
U
Pa
Cd
Ag
Re
Fr
He
S
C
Mn
Cr
Nb
Hf
Cs
N
P
Fe
Ti
Sc
Sr
F
Al B Si
NaLi HMgBe
Rh
In
Pd
Tl
Ir
Pt
Sm
Eu
Gd
Sb
Pb
Tb
Bi
Dy
Ho
Xe
Te
Hg
Au
Os
Sn
Er
Po
Tm
Rn
At
Yb
Lu
Pm
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr
14-July-2011
The Chemistry of Climate
.....and just for fun
Relative Abundance, Human
O
H
He
C
N
Li
Be
B
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
Cs
Ba
La
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
Fr
Ra
Ac
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr
14-July-2011
The Chemistry of Climate
14-July-2011
The Chemistry of Climate
Chemical composition of Atmosphere:
N2 (78.084%)
O2 (20.946%)
Ar (0.9340%)
H2O
CO2
Ne
He
CH4 • CO2, H2O, CH4, N2O, ground level O3
& CFC, HCFC
Kr
H2 • CH4, N2O,& O3 are much efficient.
N2O • Have, however, short lifetimes, leaving CO2
Xe
as the main cause of atmospheric heating.
O3
NO2 ….
14-July-2011
The Chemistry of Climate
Greenhouse Effect is essential for Life!
– Earth’s radiative balance (solar input vs. IR
output) leaves <TEarth> ~ – 20°C
• Almost all water would be ice everywhere.
• But Life requires ℓiquid water!
– H2O(g), CO2 and … absorb outbound IR and
reradiate it omnidirectionally.
• So Earth intercepts ~½ that absorbed IR and gains
<T> to +15°C.  H2O(ℓ) & we exist.
14-July-2011
The Chemistry of Climate
9G What about the greenhouse effect?
Light reaches us from the Sun.
The
Some ofgreenhouse
it is absorbed by the effect is a theory to
With more greenhouse
Earth and why
warms global
it. Some is
explain
warming
is happening.
gases,
more infrared is
reflected back into space.
reflected back to the Earth,
and it gets warmer still.
The Earth gives off infrared
radiation because it has
been warmed by the Sun.
In the atmosphere is a
layer of greenhouse gases.
Some infrared radiation is
reflected back by the greenhouse
gases. This makes the Earth
warmer than it would be without
the greenhouse gases.
The world needs the greenhouse effect. Without it the
Earth would be too cold for most organisms to live.
14-July-2011
The Chemistry of Climate
Natural
greenhouse
effect
Enhanced
greenhouse
effect
Without the greenhouse effect the
earth’s climate would be …
14-July-2011
The Chemistry of Climate
Growing CO2 warms the earth
Atmospheric CO2 was stable prior to the 19th century.
IPCC
1750
14-July-2011
The Chemistry of Climate
Global warming
Climate change is real –
the evidence is overwhelming
We can reduce the causes of climate change –
no single solution, but needs major changes in
human behaviour
Future climate change (in the next few decades)
is inevitable – we need to start preparing now
14-July-2011
The Chemistry of Climate
The warming is happening almost everywhere.
14-July-2011
9G What is acid rain?
Acid Rain
The Chemistry of Climate
Rain is naturally slightly acidic. Why?
Because carbon dioxide in the air dissolves
in the falling water to make carbonic acid.
carbon dioxide + water
normal rain
acid rain
carbonic acid
So what’s acid rain?
It’s a term used for rain that
is more acidic than normal.
Acid rain forms when acidic
gases in the air dissolve in
the rain. These gases come
from burning fossil fuels.
14-July-2011
The Chemistry of Climate
• Natural Acidity, C2(aq)
pH < 7
• S3 & N25 are strong acid anhydrides.
Acid Rain
14-July-2011
The Chemistry of Climate
9G How is acid rain formed?
Acid rain can fall many miles from the source of the pollution.
Acid gases react together
in the clouds – sunlight
encourages this reaction.
Acid gases
rise in the air.
Dry deposition – acid
particles fall to the
ground in dust.
Falling rain dissolves
the acidic gases.
Acid rain falls to the ground.
It makes soil, lakes and
rivers more acidic.
Burning fuels release acidic gases,
mainly sulphur dioxide (power stations)
and oxides of nitrogen (vehicles).
14-July-2011
9G How acidic is acid rain?
The Chemistry of Climate
How does Acid rain compare with other acids?
Match the pH to the substance.
substance
pH 3
pH 6
pH 2
pH 7
pH 4 pH 1
pH
pure water
unpolluted rain
acid rain from a polluted area
Vinegar
car battery acid
acid in your stomach
14-July-2011
The Chemistry of Climate
9G It takes a while...
Acid rain is a dilute acid solution. The acid in
your stomach is stronger and more corrosive.
But acid rain is dangerous because it acts over many
years.
Think how much rain falls on a building over 200 years!
Even a slight increase in the acidity of rain could
have serious effects over this timescale.
And because the changes from day to
day are small, people do not notice them.
14-July-2011
9G But the effects are serious
The Chemistry of Climate
What problems does acid rain cause?
Acid rain reacts to dissolve
away rocks such as limestone.
This destroys valuable buildings.
It makes rivers and lakes more acidic.
This causes problems on moors and mountains
where the ground is already acidic.
It allows poisonous chemicals such as aluminium salts
to dissolve in water and soil. They poison trees and fish.
It reduces the growth of plants, including food crops.
14-July-2011
The Chemistry of Climate
14-July-2011
Any question
Thanks
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