Presentation on theme: "Climate Change A Meteorological Perspective William Kininmonth Melbourne, Australia."— Presentation transcript:
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
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 Earths orbital variations around the 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 ago o The warming was not regular and temperatures have fluctuated for the past 10,000 years o We are not in the warmest phase of the interglacial Greenland
A return to the drier climate of the first half of the 20th century Murray-Darling Basin Rainfall Source: 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 Anomaly Source: Bureau of Meteorology from Hadley Centre, UK Global warming has taken place over two intervals: 1910 – 1940 and
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 earths surface emits more infrared than it absorbs and the net infrared loss tends to cool the surface. An Incorrect Statement
The Global Energy Budget- IPCC Longwave radiation cools the atmosphere and the earths surface Atmosphere: emission = = 519 absorption = =417 Surface:emission = 390; absorption = 324 Loss = 102 Loss = 66
Net Radiation Loss From The Atmosphere -102 W/m 2 Net Radiation Gain At The Surface +102 W/m 2 There is net radiation gain at the earths surface 168 – (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 Earths 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 -6.5 o C/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
Carbon dioxides 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
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 1 o C
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 1 o C temperature rise, 5.4 Wm -2 for radiation and 6.0 Wm -2 for Latent heat Temperature response (Conservation of energy) ΔT 1 = Forcing/Rate of surface energy loss = 3.7/( ) = 0.3 o C
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 = ΔT 1 (1 + r + r 2 + r 3 + r ) r = rate of increase in back radiation rate of surface energy loss ΔT = ΔT 1 /(1 – r)
Global Temperature Rise is Constrained The earths 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 CO 2 will, with feedbacks, only raise the surface temperature by about 0.5 o C
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 2 o C 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
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 clear The climate must be perfect all the year. Outside Camelot we cannot change climate We must adapt to survive