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Climate Change A Meteorological Perspective

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Presentation on theme: "Climate Change A Meteorological Perspective"— Presentation transcript:


2 Climate Change A Meteorological Perspective
William Kininmonth Melbourne, Australia

3 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

4 Ice Core Record - VOSTOK, Antarctica
The ice core provides a climate record of the past 450,000 years Earth is currently in an interglacial period of relative warmth The glacial cycles are regulated by the Earth’s orbital variations around the Sun Temperature Carbon dioxide Dust Over the last million years the Earth's climate has fluctuated regularly and violently between glacial and interglacial conditions. The ice core record from Vostok in Antarctica clearly shows the fluctuations of temperature, carbon dioxide and aerosols over the last 450,000 years. About each 100,000 years the Earth moved through a glacial-interglacial cycle. Each glacial period of gradual cooling covered about 80,000 years followed by a dramatic temperature rise to a warmer interglacial lasting about 10,000 years. The atmospheric carbon dioxide concentration varied with temperature, with a lag of nearly 1,000 years during the warming phase. Carbon dioxide did not initiate nor amplify the warming. Each warming event ceased at a similar temperature, although the current interglacial is not quite as warm as previous events. Accumulating dust reflects the global aridity during the glacial periods. As Earth warmed so to evaporation increased nearly exponentially with temperature and supporting more abundant vegetation to bind soils. Carbon dioxide follows Temperature Glacial periods are dry and dusty - sea level 130 m lower than now

5 The great global warming event
Greenland The great global warming event 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 The great global warming event 20,000 years ago Earth was in a glacial period. Ice sheets covered North America as far south as Vancouver, St Louis and New York; and Europe as far south as London. What is now Chicago was under 1 km of ice. Sea level was 130 m lower than now such that New Guinea and Tasmania were connected to the Australian continent by land bridges. The maximum water distance between Australia and Asia was about 100 km. The now pristine Great Barrier Reef was limestone cliffs and the many coral atolls of the Pacific were small islands. Port Phillip Bay was a plain with the Yarra River flowing to the Southern Ocean across a plain that is now Bass Strait. Australia was much drier than now with great inland dunes formed from blowing sand. A great warming event commenced about 19,000 years ago as the land ice began to melt and sea levels rose. The warming was interrupted by the extended cold of the Younger-Dryas. The current relatively warm and wet interglacial has lasted nearly 10,000 years. Temperatures have not been constant but have fluctuated, with warmer and wetter conditions between 10,000 and 5,000 years ago. The recent Medieval Warm Period and Little Ice Age are typical of the variability.

6 Murray-Darling Basin Rainfall
Source: Bureau of Meteorology A return to the drier climate of the first half of the 20th century Australia’s rainfall Climate predictions of a drier future must be assessed in terms of recorded climate. The rainfall of the Murray-Darling Basin over the past century is indicative of the natural variability. There is significant year-to-year variability. The rainfall was in three phases: A dry period prior to about 1950, A wetter period between about 1950 and 2000, and A return to the drier conditions of the early half of the century. There is no reason to believe that the recent dry can be attributed to greenhouse caused global warming

7 Human-caused Global Warming?
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 New Mythology - Carbon dioxide The newest proselytisers of human-caused weather makers come armed with the mysticism of computer models in support of their cause. With arguments and evidence no more compelling than their witch-hunting predecessors of earlier centuries, the grand priests will have us believe that continued burning of fossil fuels will lead to the downfall of humankind. Runaway global warming is the new fear. It is not enough to recognise that fossil fuels are a non-renewable form of energy. These prophets of doom insist that we abandon the dirty energy of coal-fired power stations, automobiles and aircraft. The development and technological evolution of renewable energy sources will take place in their season. We are being blackmailed into compliance to a low carbon regime because of the threat of an apocalyptic threat for which there is no direct evidence - only the smoke and mirrors of computer model projections.

8 The rate of burning of fossil fuel is increasing.
Burning of fossil fuels has increased, especially since World War II. About 8,000 million tons of carbon are burned and emitted to the atmosphere each year. This compares to natural exchange of about 210,000 million tons of carbon as CO2 between the atmosphere and the oceans and between the atmosphere and the biosphere. There is about 800,000 tons of carbon as carbon dioxide in the atmosphere. Only about half of the human-caused carbon dioxide emissions are retained in the atmosphere beyond a year. The remainder is taken back by the oceans and the biosphere. The atmospheric carbon dioxide increase is about one-half of one percent per year. Does it matter? 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?

9 Global Annual Mean Temperature Anomaly
Source: Bureau of Meteorology from Hadley Centre, UK Global warming has taken place over two intervals: 1910 – 1940 and

10 An Incorrect Statement 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. An Incorrect Statement From IPCC

11 The Global Energy Budget- IPCC Longwave radiation cools the atmosphere and the earth’s surface
Atmosphere: emission = = 519 absorption = =417 Surface: emission = 390; absorption = 324 Loss = 102 Loss = 66

12 The Global Energy Balance
How is excess radiation energy transferred to the atmosphere to balance the net radiation loss? There is net radiation gain at the earth’s surface 168 – (390 – 324) = +102 Net Radiation Loss From The Atmosphere -102 W/m2 Net Radiation Gain At The Surface +102 W/m2

13 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. Deep convection towers, with more energy than nuclear explosions, are continually distributing energy through the atmosphere. Water vapour and carbon dioxide are the principal greenhouse gases and they are continually radiating energy to space and cooling the atmosphere. Radiation from the Sun is continually warming the Earth's surface, mostly in the tropics. Conduction and evaporation transfer heat and latent energy to the atmosphere near the ground. Deep buoyant convection clouds are essential to transfer the excess solar energy from the surface through the atmosphere and offset the energy loss from radiation. The energy of nuclear explosions do not affect climate and there is no evidence of lasting aerosols. Mega-volcanic explosions, by contrast, do blast dust into the stratosphere that lingers for several years and that have a temporary cooling on climate.

14 The Enhanced Greenhouse Effect
Additional carbon dioxide in the atmosphere: Reduces longwave radiation to space Increases back radiation at the surface

15 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 Carbon dioxide is an active greenhouse gas in two bands of the radiation spectrum. The other important greenhouse gas is water vapour. The effect of carbon dioxide in the atmosphere is to reduce radiation emission to space in the bands at which it is active. The major effect is in the first 50 ppm of concentration when the radiation is reduced by about 19 W/m2. For context, the total radiation emitted to space is about 235 W/m2. An 8 percent reduction is not insignificant. A doubling of the concentration to 100 ppm further reduces the emission in the carbon dioxide bands by 2.8 W/m2, or an additional 1 percent. A further doubling of the concentration to 200 ppm reduces the radiation to space in the carbon dioxide bands by an additional 2.8 W/m2. That is, another 1 percent. This brings us to the concentration at the time of the last glacial maximum 20,000 years ago. A further doubling of the concentration to the current levels of about 400 ppm only reduced the emission in the carbon dioxide bands by an additional 1 percent. If we continue burning fossil fuels and double the concentration over this century then the reduction in emission in the carbon dioxide bands will be only 1 percent. Given the natural variability of the climate system then this is not likely to be perceptible from cyclic warming and cooling.

16 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) Runaway Global Warming Tipping Points Irreversibility

17 Surface energy exchanges vary with temperature

18 Carbon dioxide forcing increases surface temperature by less than 1oC

19 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/( ) = 0.3oC

20 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 + r ) r = rate of increase in back radiation rate of surface energy loss ΔT = ΔT1 /(1 – r)

21 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/( ) = 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

22 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’

23 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 Man-made global warming is an illusion Recent climate and its characteristic of warming is neither unusual nor unprecedented. It is within the envelope of past climate variations. Carbon dioxide is an active greenhouse gas but its potential for further impact on climate is limited. The climate system is extremely complex. The ocean and atmosphere are fluids in motion that constantly interact to transport energy around the Earth from regions of excess to regions of deficit and achieve global energy balance. We will look at these three issues in turn.

24 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. Warm Cold Proxy Temperature Solar Forcing

25 Variations of ocean circulations regulate climate
The climate system has natural internal variability due to the interaction between the atmosphere and ocean fluids. All of the energy of the atmosphere is in the top 3 metres of the oceans and so the oceans are the thermal and inertial flywheels of the climate system. The diagram is a depth cross-section of the Pacific Ocean along the equator from New Guinea on the left to South America on the right. The scale is distorted, being 10,000 km across but only 500 metres deep. In addition there are 4-5 km of very cold water (the cold abyss) below the section represented. What we see is the impact of the easterly Trade Winds blowing across the Pacific with wind stress piling up warm water on the west. This is the La Nina phase. Occasionally the warm waters spread eastward causing characteristic drought and flood. El Nino is a dramatic form of climate variability on interannual timescales. There are a range of other cycles operating on decadal, multi-decadal and longer timescales. Although the Sun has been warming the tropical oceans for billions of years there is an upper limit to surface temperature of about 30C because of the moderating effect of evaporation. It is inconceivable that small changes in radiation due to carbon dioxide will appreciably warm the surface temperatures. Increased upwelling will bring on cooler conditions globally.

26 SUMMARY Carbon dioxide from modern industry and agriculture
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. 1. The climate system is highly variable on all timescales and communities have adapted to their local climate. 2. Climate extremes are hazardous to communities. 3. Climate change will destroy some communities, as has happened in the past. 4. There are many uncertainties as to the causes of climate variability and long term change - we should not succumb to mysticism and illusion. 5. Carbon dioxide from modern industry and agriculture has only limited influence on climate.

27 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

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