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Published byKenneth Copeland Modified over 9 years ago
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Climate change impacts Glaciers
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Climate science The Greenhouse effect: –Natural: Water vapour Carbon dioxide –Human produced: Carbon dioxide Methane etc. Human produced
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A Question What is the average temperature of the Earth? 1 metre above the surface and averaged over: day and night, all latitudes and longitudes. all seasons (a) – 15 ° C (b) – 5 ° C (c) + 5 ° C (d) + 15 °C
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A Question What is the average temperature of the Earth? 1 metre above the surface and averaged over: day and night, all latitudes and longitudes. all seasons (a) – 15 ° C (b) – 5 ° C (c) + 5 ° C (d) + 15 °C
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Absorption bands © Australian Bureau of Meteorology Wavelength Water Absorptio n CO 2 Absorptio n Infra Red from Earth UV from the Sun
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Absorption bands Illumination by the Sun © Australian Bureau of Meteorology Wavelength Water Absorptio n CO 2 Absorptio n Infra RedUV from the Sun
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Absorption bands Radiation from the Earth © Australian Bureau of Meteorology Wavelength Water Absorptio n CO 2 Absorptio n Infra RedUV from Earth (drawn on a different scale)
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The transmittance of water vapour Visible Infra Red
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The spectrum of sunlight Infra RedUV
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Diagrams from : Bob Crowder The Wonders of the Weather Melbourne, Bureau of Meteorology 2000: p 22-23. Sun Earth Emission spectra for the Sun and Earth
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Climate science Interactions between EMR and the atmosphere: –Blackbody spectra –Sun and Earth (but note that Earth is less than a millionth of the Sun) Also note that the IR absorbed from the Sun is of much shorter wavelength than that emitted by the Earth – UV Vis short IR – long IR
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Climate Models: Results What is the output of a climate model?
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Courtesy of Graeme Pearman
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Climate science Interactions between EMR and the atmosphere: –Types of spectra: This is what we are interested in.
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The effect of changes – Feedback and Forcing –H2O 95% should actually be 90-95% and is for clouds also. –Can’t simply subtract leaving 5-10% for GHGs. –H2O and CO2 absorb different parts of the IR radiation spectrum. Climate Real science H2O CO2 CH4
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Climate Real science The effect of changes – Feedback and Forcing –Anthropogenic CO2 is NOT 3%!
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The spectrum of sunlight
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A family’s CO 2 emissions 0.3 kg per km 4000 km per year 1200 kg CO 2 /year 0.3 kg per km per person 1000 km per year 600 kg CO 2 /year 0.5 kg per kWh 7300 kWh per year 3650 kg CO 2 /year
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A family’s CO 2 emissions 5450 kg of CO 2 per year Over 5 tonnes!
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Observed changes Best estimates
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Expressing concern What can we do? Sustainable options This is in sunny Germany!
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Radiative forcing concentrations Intergovernmental panel on Climate Change (2007) Climate Change 2007: The Physical Science Basis (Summary for Policymakers) Figure SPM2 p16: Radiative forcing components Accessed at www.ipcc.ch (11/5/2007)
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Contributions to Climate Forcing Greenhous e gases Carbon Dioxide Methane Chlorofluorocarbons Nitrous Oxide Ozone Aerosols Black Carbon Reflective aerosols Cloud droplet changes Land cover changes Sun Climate Forcing (W/m 2 ) 0+1
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IPCC Predictions…
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Methane concentrations Intergovernmental panel on Climate Change (2007) Climate Change 2007: The Physical Science Basis (Summary for Policymakers) Figure SPM1 p15: Atmospheric concentration of CO 2 Accessed at www.ipcc.ch (11/5/2007)
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Carbon dioxide concentrations Intergovernmental panel on Climate Change (2007) Climate Change 2007: The Physical Science Basis (Summary for Policymakers) Figure SPM1 p15: Atmospheric concentration of CO 2 Accessed at www.ipcc.ch (11/5/2007)
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Science behind the model
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Greenhouse gases (2.5 Wm -2 ) Emitted IR radiation Natural greenhouse heating Input solar radiation (100 %) Reflected by clouds, atmosphere (~23%) Reflected from surface (~8%) Absorbed by ground (~49%) Measured absorption (25%) ~80 Wm -2 ?? Absorbed by atmosphere (20%) ~60 Wm -2 Climate Models
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Diagram from : Bob Crowder The Wonders of the Weather Melbourne, Bureau of Meteorology 2000: p 33.
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Climate models have greatly improved
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Modelled tropical cyclone
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IPCC Predictions from Climate Research Unit, East Anglia University 2008 0.5 metres in 100 years ? 1 metre
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IPCC SynRep
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Climate change impacts Australia Temperature trend
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Climate change impacts According to NASA and the climate scientists.
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Human induced changes Is the climate changing? IPCC SynRep
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Carbon Cycle 760 90 60 6.4 1.4 1.7 760 increasing at 3.2/year 2,000 39,000 500 1,000 3,000 300
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Cause for concern S ceptics, deniers, avoiders –“We are in a cooling phase” Yes but…
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Global CO 2 Emissions
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Figure 10.5
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Figure 10.8
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Figure 10.13
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Figure 10.19
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Figure 10.24
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Figure 10.33
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Figure 10.38
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Box 10.2, Figure 2
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Most important greenhouse gas (ghg) is water vapour but its concentration is determined by temperature Important long-lived ghgs are CO 2, CH 4, N 2 O Absorption by ghgs seen in satellite infrared spectra Absorption proportional to log(concentration), so doubling ghg concentration gives same heating Greenhouse effect
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‘Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.’ (IPCC 2007) WGI Fig SPM.3
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‘Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years. The global increases in carbon dioxide concentration are due primarily to fossil fuel use and land-use change, while those of methane and nitrous oxide are primarily due to agriculture.’ WGI Fig SPM.1
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Sea ice in Sept 2007 From Stroeve et al, GRL, 2007 Sept 2005
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Observed and projected Australian rainfall Best estimate projected rainfall change for 2070 (from “Climate change in Australia”) Observed trend in annual rainfall 1970-2007
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Projections of sea level rise Past sea level and sea-level projections from 1990 to 2100 based on global mean temperature projections of the IPCC TAR. From Rahmstorf, Science, 2007 From IPCC AR4
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Stabilisation scenarios 455 ppm CO 2 -eq in 2005, 379 ppm CO 2 conc I: CO 2 -eq stabilisation at 445-490 ppm, emissions peak in 2000-2015, global CO 2 emissions -85% to -50% in 2050, warming of 2.0 to 2.4 C above pi II: CO 2 -eq stabilisation at 490-535 ppm, emissions peak in 2000-2020, global CO 2 emissions -60% to -30% in 2050, warming of 2.4 to 2.8 C above pi Assuming equal per capita emissions, 50% global emission reduction in 2050 means ~90% emission reduction for US and Australia SyR Fig SPM.11
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Australian greenhouse gas emissions Sector % change in 2010 in 2020 Stationary energy +56%+64% Transport +42%+67 Land use change -68%-68% Total +8%+20% Australian emissions from energy use and transport have grown at more than 20% per decade. Australia is close to its Kyoto target only because of one-off reductions in land clearing. Dept of Climate Change “Tracking to the Kyoto target 2007”
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Other gases with greenhouse potential Source, IPCC 4AR, SPM, 2007
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Relative contribution to warming ConcentrationChange per year Radiative forcing Wm -2 <17002005 Carbon dioxide275-285379 ppmv1.9 ppmv+1.66 ±0.17 Methane7151774 ppbv~nil+0.48 ±0.05 Nitrous oxide270319 ppbv0.83 ppbv+0.16 ±0.02 CFCs HCFCs Chlorocarbons NA Slightly negative +0.32 ±0.03 Ozone - stratosphere - Troposphere -0.05 ±0.10 +0.35 ±0.30 HFC, PFC, SF 6 NA 10%+0.017 ±0.002 Total +2.63 ±0.26
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Lifetime and global warming potentials of selected greenhouse gases GasSymbolLifetime Years Global Warming Potential 20-years100-years Carbon dioxideCO 2 ~8011 MethaneCH 4 127225 Nitrous oxideN2ON2O114289298 CFC-11CCl 3 F4538004750 CFC-12CCl 2 F 2 100810010900 HFC-23CHF 3 2701170014800 Sulphur hexafluorideSF 6 32002390016300 IPCC 4AR, Chapter 2, 2007
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North Australian tropics annual sea surface temperature anomaly (from1961-1990) http://www.bom.gov.au/cgi-bin/silo/reg/cli_chg/timeseries.cgi
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Greenland Mass Loss – From Gravity Satellite
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Global Mean Temperature We stop all emissions NOW We BEGIN to stop all emissions NOW We do nothing We BEGIN to stop all emissions EVENTUALLY IPCC Predictions on Global Mean Temperature
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Intergovernmental panel on Climate Change (2007) Climate Change 2007: The Physical Science Basis (Summary for Policymakers) Figure SPM3 p17: Observed changes Accessed at www.ipcc.ch (11/5/2007)
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IPCC SynRep
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Feedback Global Temperature More Evaporation Climate Forcing Increased Climate Forcing Increased Water Vapour Increased Cloud Cover Decreased Climate Forcing Negative Positive
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SponsorAddressContent Aust. Acad. of Science http://www.science.org.au/nova/Carbon accounting, climate and health, biodiversity, health, etc. Australian Bureau of Meteorology http://www.bom.gov.au/climate/Information about climate http://www.bom.gov.au/cgi-bin/silo/reg/cli_chg/trendmaps.cgiTrends maps for Australia’s climat http://www.greenhouse.gov.au/Q and A, carbon accounting, energy Australian Greenhouse Office http://www.greenhouse.gov.au/Q and A, carbon accounting, energy, etc http://www.greenhouse.gov.au/inventory/2003/pubs/inventory2003.pdfEmission inventory http://www.greenhouse.gov.au/education/tips.htmlWhat you can do Hadley Centre, British Meteorological Office http://www.metoffice.com/research/hadleycentre/pubs/brochures/Publications http://www.metoffice.com/research/hadleycentre/models/modeldata.htmlClimate predictions http://www.metoffice.com/research/hadleycentre/obsdata/globaltemperature.htmlGlobal temperatures CRC G/H Accoun.http://www.greenhouse.crc.org.au/about%5Fgreenhouse/Greenhosue, carbon accounting, impacts, etc. CSIRO Marine and Atmospheric Research http://www.cmar.csiro.au/e-print/open/gh_faq.htm#gh1Greenhouse questions and answers http://www.dar.csiro.au/capegrim/ghgasgraphs.htmlGreenhouse-gas levels, Cape Grim http://www.dar.csiro.au/publications/projections2001.pdfClimate projections Environment Canada http://www.msc.ec.gc.ca/education/scienceofclimatechange/understanding/FAQ/F AQ-finalenglish.pdf Greenhouse questions and answers NOAAhttp://www.ncdc.noaa.gov/oa/climate/research/anomalies/anomalies.htmlGlobal data Princeton University http://www.princeton.edu/~cmi/resources/CMI_Resources_new_files/Environ_08- 21a.pdf Wedges approach to future energy options Roy. Soc. London http://www.royalsoc.ac.uk/downloaddoc.asp?id=1630Facts and fiction about climate change Concerned Scientists http://www.ucsusa.org/global_warming/science/global-warming-faq.htmlFrequently asked questions Vict. Governmenthttp://www.greenhouse.vic.gov.au/Victorian greenhouse strategy, etc. United Nationshttp://unfccc.int/2860.phpFramework Convention on Climate Chnage http://www.ipcc.ch/Recent Fourth Assessment Report
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Milankovitch Cycles Note: Time scales are reversed
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Figure prepared by Robert Rohde for Global Warming Art Project 1 metre per 100 years http://en.wikipedia.org/wiki/Sea_level _rise
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Climate models In brief, each is a complex, lengthy computer program, incorporating all physical/chemical and biological processes that drive weather and climate, reproducing the way in which climate behaves from day to day, and season to season.
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What determines the Earth’s surface temperature? For a detailed answer we need to know: How much light reaches the Earth? How much light reaches the Earth’s Surface? How much energy is radiated from the Earth’s Surface?
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Climate models These are just F = ma applied to moving fluids. This is conservation of mass. This governs the way heat flows between systems
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Dieting Program
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Science behind the water cycle
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