Transcript No Slide Title

Climate Change
A Meteorological Perspective
William Kininmonth
Melbourne, Australia
Outline
 Characteristics of past climate
 The greenhouse effect and how additional
carbon dioxide has little climate impact
 How computer models exaggerate global
temperature response and why dangerous
human-caused global warming is an
illusion
Ice Core Record - VOSTOK, Antarctica
The ice core provides
a climate record of the
past 450,000 years
Temperature
Carbon dioxide
Dust
• Carbon dioxide follows Temperature
• Glacial periods are dry and dusty
- sea level 130 m lower than now
Earth is currently in an
interglacial period of
relative warmth
The glacial cycles are
regulated by the Earth’s
orbital variations around
the Sun
Greenland
The great global warming event
o
o
o
Earth began to warm about 20,000 years ago
The warming was not regular and temperatures have
fluctuated for the past 10,000 years
We are not in the warmest phase of the interglacial
Murray-Darling Basin Rainfall
Source: Bureau of Meteorology
Annual Rainfall Anomaly
400
300
100
2005
2000
1995
1990
1985
1980
1975
1970
1965
1960
1955
1950
1945
1940
1935
1930
1925
1920
1915
1910
-100
1905
0
1900
Rainfall (mm)
200
A return to the drier climate of
the first half of the 20th century
-200
-300
Years
1000
600
500
550
Decadal Average Annual Rainfall (mm)
Long-term average = 478 mm
500
2005
2000
1995
1990
1985
1980
1975
1970
1965
1960
1955
1950
1945
1940
1935
1930
1925
1920
1915
1910
1905
0
1900
Accumulated Anomaly (mm)
Accumulated Annual Rainfall Anomaly
450
-500
400
-1000
350
-1500
300
-2000
Years
Years
Loy Yang A
Human-caused Global Warming?
 It is claimed that burning fossil fuel will pollute
the atmosphere with carbon dioxide leading
to global warming and dangerous climate
change!
•
•
•
The rate of burning of fossil fuel is increasing.
Carbon dioxide concentration in the atmosphere is increasing.
How much will it enhance the greenhouse effect?
Global Annual Mean Temperature Anomaly
Source: Bureau of Meteorology from Hadley Centre, UK
 Global warming has taken place over two intervals:
1910 – 1940 and 1976 - 2000



Greenhouse gases emit infrared radiation independently of absorption
The greenhouse gases of the atmosphere emit more infrared radiation (to space
and back to the surface) than they absorb and tend to cool the atmosphere.
The earth’s surface emits more infrared than it absorbs and the net infrared loss tends
to cool the surface.
An
Incorrect
Statement
From IPCC
The Global Energy Budget- IPCC
Longwave radiation cools the atmosphere and the earth’s surface
Atmosphere:
emission = 195 + 324 = 519
Loss = 102
absorption = 350 + 67 =417
Surface:
emission = 390; absorption = 324
Loss = 66
The Global Energy Balance
How
radiationgain
energy
transferred
to the
Thereisisexcess
net radiation
at the
earth’s surface
atmosphere168
to balance
net =radiation
– (390 –the
324)
+102 loss?
Net Radiation Loss From The Atmosphere
-102 W/m2
Net Radiation Gain At The Surface
+102 W/m2





Solar energy penetrates the atmosphere and warms the Earth’s surface.
Deep convection towers are constantly distributing energy from the surface
through the atmosphere.
The atmosphere radiates energy to space
Buoyant convection requires an atmospheric temperature lapse rate greater
than -6.5oC/km in the lower troposphere (the moist adiabatic lapse rate).
The need for buoyant convection is why the surface is warmer than the middle
troposphere (where the IR emission to space emanates) – the greenhouse effect.
The Enhanced Greenhouse Effect
Additional carbon dioxide in the atmosphere:
1. Reduces longwave radiation to space
2. Increases back radiation at the surface
Radiation forcing increments (W/m2)
Radiation Forcing increments with CO2 increase
25.0
20.0
15.0
10.0
5.0
0.0
Reduction in Infrared
Radiation Emission to Space
50
100
200
400
800
19.2
2.8
2.8
2.8
2.8
Incremental increase in CO2 concentration
Carbon dioxide’s diminishing impact
 The main forcing was in the first 50 ppm concentration
 Doubling concentration from 400 ppm to 800 ppm
will have little additional impact on radiation
Is Dangerous Global Warming Feasible?
 There is a greenhouse effect
 Increasing Carbon dioxide in the atmosphere will enhance
the greenhouse effect
 How much will temperature rise?
 Temperature is limited by evaporation
in hot climates
- C.H.B. Priestley (CSIRO, 1966)
Surface energy exchanges vary with temperature
Variation of Surface Energy Loss with Temperature
US Standard Atmosphere - clear sky
Surface energy loss Wm-2
600
500
400
300
200
100
0
0
5
Latent heat exchange
10
15
Temperature oC
Net longwave loss
20
Surface Emission
25
Back Radiation
30

Carbon dioxide forcing increases
surface temperature by less than 1oC
Variation of Surface Energy Loss with Temperature
US Standard Atmosphere - clear sky
Surface energy loss Wm-2
260.0
240.0
220.0
200.0
With carbon dioxide forcing
180.0
10
15
Temperature oC
Total surface loss
Solar absorption
20
CO2 Forcing
Direct Surface Temperature Response
Surface energy input - Radiation forcing
 The direct carbon dioxide forcing of 3.7 Wm-2 (IPCC)
Increase in rate of surface energy loss
 As the surface temperature increases, heat loss from
the surface increases by radiation emission and by
evaporation of latent heat:
- for each 1oC temperature rise, 5.4 Wm-2 for radiation
and 6.0 Wm-2 for Latent heat
Temperature response (Conservation of energy)
ΔT1 = Forcing/Rate of surface energy loss = 3.7/(5.4 + 6.0)
= 0.3oC
Feedback Amplification of Direct Forcing
 Atmospheric temperature increases with surface temperature
and water vapour concentration increases with temperature
 There is an incremental increase in back radiation that gives
an incremental increase in surface temperature
 Each incremental increase in surface temperature causes a
further increase in back radiation and a further incremental
increase in surface temperature
 The total increase of surface temperature is given by:
ΔT = ΔT1 (1 + r + r2 + r3 + r4 + .........)
r = rate of increase in back radiation
rate of surface energy loss
ΔT = ΔT1 /(1 – r)
Global Temperature Rise is Constrained
 The earth’s surface is 70% ocean and a further large
fraction is transpiring vegetation
 The feedback ratio,
r = 4.8/(5.4 + 6.0) = 4.8/11.4 = 0.4 and the
amplification gain = [1/(1 – r)]
is constrained to about 1.7
 Doubling of CO2 will, with feedbacks,
only raise the surface temperature by
about 0.5oC
Computer Models Exaggerate Projected
Global Warming
 The direct forcing of surface temperature and the water
vapour feedback are sensitive to the specification of
surface evaporation
 Computer models, on average, under-specify
evaporation increase with temperature by a factor of
three and erroneously increase the amplification gain
 Under-specification of evaporation leads to false
temperature projections of greater than 2oC
 Some computer models grossly underestimate
evaporation increase and border on
computational instability
– misinterpreted as ‘runaway global warming’
Dangerous human-caused global warming
is an illusion
 Increasing carbon dioxide in the atmosphere has
little additional radiative forcing of climate
 Computer models do not adequately simulate important
energy exchange processes of the climate system and
exaggerate temperature response to carbon dioxide forcing
 Computer predictions of dangerous anthropogenic global
warming are exaggerated
 Runaway global warming is physically impossible
Context of Climate Change
The global temperature has significantly changed
over the past five million years.
Not only has Earth cooled but the magnitude of
cyclic fluctuations has increased.
Solar Forcing
Proxy Temperature
Cold
Warm
Variations of ocean circulations regulate climate
SUMMARY
 The climate system is naturally variable on all timescales.
- Climate extremes are hazardous.
 Communities must develop resilience to withstand the hazards
of cyclic climate variability and extremes.
 There are many uncertainties and unknowns as to the
causes of climate variability and long term change
- we should not succumb to mysticism and illusion.
 Carbon dioxide from modern industry and agriculture
is not a pollutant. It has only limited influence on
climate but is beneficial to plant growth through
enhancing photosynthesis.
Its true! Its true! The king has made it clear
The climate must be perfect all the year.
Outside Camelot we cannot change climate
We must adapt to survive