Climate ChangeA 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

The ice core provides a climate record of thepast 450,000 years

Earth is currently in an interglacial period ofrelative warmth

The glacial cycles areregulated by the Earth’sorbital variations aroundthe Sun

Ice Core Record - VOSTOK, Antarctica

Temperature

Carbon dioxide

Dust

• Carbon dioxide follows Temperature• Glacial periods are dry and dusty

- sea level 130 m lower than now

The great global warming event

o Earth began to warm about 20,000 years agoo The warming was not regular and temperatures have fluctuated for the past 10,000 yearso We are not in the warmest phase of the interglacial

Greenland

A return to the drier climate ofthe first half of the 20th century

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Accumulated Annual Rainfall Anomaly

Murray-Darling Basin RainfallSource: Bureau of Meteorology

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 AnomalySource: Bureau of Meteorology from Hadley Centre, UK

Global warming has taken place over two intervals:1910 – 1940 and 1976 - 2000

From IPCC

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.

AnIncorrectStatement

The Global Energy Budget- IPCCLongwave radiation cools the atmosphere and the earth’s surface

Atmosphere: emission = 195 + 324 = 519absorption = 350 + 67 =417

Surface: emission = 390; absorption = 324

Loss = 102

Loss = 66

Net Radiation Loss From The Atmosphere

-102 W/m2

Net Radiation Gain At The Surface+102 W/m2

There is net radiation gain at the earth’s surface168 – (390 – 324) = +102

How is excess radiation energy transferred to the atmosphere to balance the net radiation loss?

The Global Energy Balance

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 EffectAdditional carbon dioxide in the atmosphere:

1. Reduces longwave radiation to space2. Increases back radiation at the surface

Radiation Forcing increments with CO2 increase

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Incremental increase in CO2 concentration

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Reduction in InfraredRadiation Emission to Space

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Carbon dioxide’s diminishing impact

The main forcing was in the first 50 ppm concentration

Doubling concentration from 400 ppm to 800 ppmwill have little additional impact on radiation

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)

Is Dangerous Global Warming Feasible?

Surface energy exchanges vary with temperature

Carbon dioxide forcing increases surface temperature by less than 1oC

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 lossAs 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 haslittle 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

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.

Warm

Cold

Proxy Temperature

Solar Forcing

Context of Climate Change

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 clearThe climate must be perfect all the year.

Outside Camelot we cannot change climateWe must adapt to survive