2 Climate Change A Meteorological Perspective William KininmonthMelbourne, Australia
3 Outline Characteristics of past climate The greenhouse effect and how additional carbon dioxide has little climate impactHow 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 providesa climate record of thepast 450,000 yearsEarth is currently in aninterglacial period ofrelative warmthThe glacial cycles areregulated by the Earth’sorbital variations aroundthe SunTemperatureCarbon dioxideDustOver 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 TemperatureGlacial periods are dry and dusty- sea level 130 m lower than now
5 The great global warming event GreenlandThe great global warming eventEarth began to warm about 20,000 years agoThe warming was not regular and temperatures havefluctuated for the past 10,000 yearsWe are not in the warmest phase of the interglacialThe great global warming event20,000 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 MeteorologyA return to the drier climate ofthe first half of the 20th centuryAustralia’s rainfallClimate 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, andA 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 AHuman-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 dioxideThe 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, UKGlobal warming has taken place over two intervals:1910 – 1940 and
10 An Incorrect Statement From IPCC Greenhouse gases emit infrared radiation independently of absorptionThe 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.AnIncorrectStatementFrom IPCC
11 The Global Energy Budget- IPCC Longwave radiation cools the atmosphere and the earth’s surface Atmosphere: emission = = 519absorption = =417Surface: emission = 390; absorption = 324Loss = 102Loss = 66
12 The Global Energy Balance How is excess radiation energy transferred to theatmosphere to balance the net radiation loss?There is net radiation gain at the earth’s surface168 – (390 – 324) = +102Net Radiation Loss From The Atmosphere-102 W/m2Net 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 spaceBuoyant 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 spaceIncreases back radiation at the surface
15 Carbon dioxide’s diminishing impact The main forcing was in the first 50 ppm concentrationDoubling concentration from 400 ppm to 800 ppmwill have little additional impact on radiationCarbon 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 effectIncreasing Carbon dioxide in the atmosphere will enhancethe greenhouse effectHow much will temperature rise?Temperature is limited by evaporation in hot climates- C.H.B. Priestley (CSIRO, 1966)Runaway Global WarmingTipping PointsIrreversibility
18 Carbon dioxide forcing increases surface temperature by less than 1oC
19 Direct Surface Temperature Response Surface energy input - Radiation forcingThe direct carbon dioxide forcing of 3.7 Wm-2 (IPCC)Increase in rate of surface energy lossAs the surface temperature increases, heat loss fromthe surface increases by radiation emission and byevaporation of latent heat:for each 1oC temperature rise, 5.4 Wm-2 for radiationand 6.0 Wm-2 for Latent heatTemperature 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 temperatureand water vapour concentration increases with temperatureThere is an incremental increase in back radiation that givesan incremental increase in surface temperatureEach incremental increase in surface temperature causes afurther increase in back radiation and a further incrementalincrease in surface temperatureThe total increase of surface temperature is given by:ΔT = ΔT1 (1 + r + r2 + r3 + r )r = rate of increase in back radiationrate of surface energy lossΔT = ΔT1 /(1 – r)
21 Global Temperature Rise is Constrained The earth’s surface is 70% ocean and a further large fraction is transpiring vegetationThe feedback ratio,r = 4.8/( ) = 4.8/11.4 = 0.4 and theamplification gain = [1/(1 – r)]is constrained to about 1.7Doubling 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 evaporationComputer models, on average, under-specify evaporation increase with temperature by a factor of three and erroneously increase the amplification gainUnder-specification of evaporation leads to false temperature projections of greater than 2oCSome computer models grossly underestimate evaporation increase and border on computational instability– misinterpreted as ‘runaway global warming’
23 Dangerous human-caused global warming is an illusionIncreasing carbon dioxide in the atmosphere haslittle additional radiative forcing of climateComputer models do not adequately simulate important energy exchange processes of the climate system and exaggerate temperature response to carbon dioxide forcingComputer predictions of dangerous anthropogenic global warming are exaggeratedRunaway global warming is physically impossibleMan-made global warming is an illusionRecent 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 changedover the past five million years.Not only has Earth cooled but the magnitude ofcyclic fluctuations has increased.WarmColdProxy TemperatureSolar 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 hazardsof cyclic climate variability and extremes.There are many uncertainties and unknowns as to thecauses of climate variability and long term change- we should not succumb to mysticism and illusion.Carbon dioxide from modern industry and agricultureis not a pollutant. It has only limited influence onclimate but is beneficial to plant growth throughenhancing photosynthesis.1. The climate system is highly variable on all timescalesand communities have adapted to their local climate.2. Climate extremes are hazardous to communities.3. Climate change will destroy some communities, as hashappened in the past.4. There are many uncertainties as to the causes ofclimate variability and long term change - we should notsuccumb to mysticism and illusion.5. Carbon dioxide from modern industry and agriculturehas 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 climateWe must adapt to survive