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The Science of Climate Change: Explaining why we need to act NOW Prepared with material from NPL (UK), IPCC, BOM (Aus) Australian Institute of Physics (Vic Branch) Education Committee Why the urgency? Temperature Now 389ppm 400 2 CO Concentration (PPM) 350 300 Carbon dioxide 250 200 150 100 50 0 1700 variation in the last few million years 1750 1800 1850 1900 1950 Australian Institute of Physics (Vic Branch) Year Education Committee 2000 The Science of Climate Change: Explaining why we need to act NOW 1. The Earth’s atmosphere 2. 3. 4. 5. 6. Radiation and Greenhouse Effect What is a Climate Model? How has the climate already changed? What do the models predict? Cause for concern Expressing concern Australian Institute of Physics (Vic Branch) Education Committee 1. The Earth’s Atmosphere The gases in the atmosphere took some time to reach their current proportions. 4.5 billion years ago rock fragments orbiting the sun formed a rocky planet. Volcanoes produced the first atmosphere, nearly all water vapour and some gases including sulfur dioxide (SO2), carbon dioxide (CO2) and ammonia (NH3). The water condensed to form the oceans. Early aquatic life produced oxygen. Oxygen enabled more complex life forms to evolve about 500 million years ago. Australian Institute of Physics (Vic Branch) Education Committee 1. The Earth’s Atmosphere In the last 500 million years the composition of the atmosphere has been largely unchanged, but the climate has swung between ‘Hothouse Earth’ and ‘Snowball Earth. Australian Institute of Physics (Vic Branch) Education Committee 1. The Earth’s Atmosphere Causes of Climate Changes Variations in Earth’s orbit Changes in greenhouse gases Movement of continents Uplift of Tibetan plateau Variation in Sun’s output Volcanoes Australian Institute of Physics (Vic Branch) Education Committee The Science of Climate Change Australian Institute of Physics (Vic Branch) Education Committee Australian Institute of Physics (Vic branch) Education Committee Bubbles in Antarctic Ice Maximum Value 300 ppm 400 350 CO2 (ppmv) 300 250 200 150 100 50 0 400 Minimum Value 180 ppm 350 300 250 200 Ice Ages 150 100 Thousands of years before the present Australian Institute of Physics (Vic Branch) Education Committee 50 0 Carbon Dioxide in the atmosphere Current value 389 ppm 400 2 CO Concentration (PPM) 350 300 250 200 150 100 50 0 1700 variation in the last few million years 1750 1800 1850 1900 Year Australian Institute of Physics (Vic Branch) Education Committee 1950 2000 The Science of Climate Change: Explaining why we need to act NOW 1. The Earth’s atmosphere 2. Radiation and Greenhouse Effect 3. 4. 5. 6. What is a Climate Model? How has the climate already changed? What do the models predict? Cause for concern Expressing concern Australian Institute of Physics (Vic Branch) Education Committee Electromagnetic Radiation It is radiation from the Sun that is our ultimate energy source, it underpins life on the planet. This radiation comes in many forms. They differ from each other in the same way as the signals from radio stations differ. They differ only in the frequency, and because they are all waves, also in their wavelength. Australian Institute of Physics (Vic Branch) Education Committee Electromagnetic radiation from a hot body How does an object get hot when placed in front of a fire? Australian Institute of Physics (Vic Branch) Education Committee Electromagnetic radiation from a hot body This radiation is called Blackbody radiation, because it has nothing to do with the inherent colour of the object. Hot objects give out much more radiation than warm objects, Hotter objects give out shorter wavelengths. Australian Institute of Physics (Vic Branch) Education Committee Electromagnetic Radiation The atmosphere absorbs some forms, scatters others and allows others to pass through. UV is absorbed by Ozone in the upper atmosphere. Blue light is scattered more than red, making the sky blue. Some infra red is absorbed by water and CO2. Australian Institute of Physics (Vic Branch) Education Committee Radiation The Earth also emits radiation, but the Earth is much cooler and dimmer. The earth radiates in the longer wavelengths of infrared, and with much less intensity. Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? Light from the Sun heats the Earth… Light from the Sun Earth The Earth then radiates the heat away… Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? heat input from the Sun heat lost from the Earth by radiation When there is balance, the Earth’s average temperature will be stable Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? Light from the Sun heats the Earth… •At the top of the atmosphere •Above the Equator •At midday •About 1360 W/m2 Australian Institute of Physics (Vic Branch) Education Committee Earth What determines the Earth’s surface temperature? Light from the Sun heats the Earth… Earth 680 North Pole 1360 W/m2 Equator Whole Earth Average 340 W/m2 Australian Institute of Physics (Vic Branch) Education Committee South Pole What determines the Earth’s surface temperature? Light reflected from Earth Average Value 100 watts per square metre Light from the Sun Average Value 340 watts per square metre Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? Light from the Sun heats the Earth… Average Value 240 watts per square metre Average Value 240 watts per square metre Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? How hot must the Earth be to radiate 240 W/m2 ? Average Value 240 watts per square metre -18 °C Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? Actual average +15 °C surface temperature 33 °C Temperature for radiation balance -18 °C Australian Institute of Physics (Vic Branch) Education Committee Greenhouse Effect What determines the Earth’s surface temperature? The Earth’s surface is 33 °C warmer than it would be if it had no atmosphere So how does the atmosphere warm the Earth’s surface? Australian Institute of Physics (Vic Branch) Education Committee Gases in the Atmosphere O2 N2 About 100 molecules Ar Australian Institute of Physics (Vic Branch) Education Committee Gases in the Atmosphere About 1200 molecules Water(H2O) Australian Institute of Physics (Vic Branch) Education Committee Gases in the Atmosphere About 10000 molecules Carbon dioxide (CO2) Australian Institute of Physics (Vic Branch) Education Committee Gases in the Atmosphere - Now Concentration in 19th century Added in 20th Century Carbon dioxide (CO2) Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? Nitrogen (N2), Oxygen (O2) & Argon (Ar) • More than 99% of the atmosphere • These molecules have one or two atoms • They block some ultra-violet light, but • Allow infra-red and visible radiation through. Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? With an atmosphere of Nitrogen Oxygen & Argon, what would be the surface temperature? Average Value 240 watts per square metre Average Value 240 watts per square metre -18 °C Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? Greenhouse warming is caused by Water (H2O) Carbon Dioxide (CO2) Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? What is special about H2O and CO2? • Their molecules have three atoms, • Their natural frequencies of vibration are in the infra-red, • They are the earth’s blanket for reflecting certain infra-red frequencies back down to earth. Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? What is special about H2O and CO2? Their molecules vibrate or jiggle in a variety of ways. So, many infrared frequencies can make them move. All these frequencies are absorbed. Australian Institute of Physics (Vic Branch) Education Committee Infrared Bands absorbed by Water and CO2 Ultra Violet Visible Australian Institute of Physics (Vic Branch) Education Committee Infra Red What determines the Earth’s surface temperature? • Out of balance… Average: 240 W/m2 Average: less than 240 W/m2 Some sent back to Earth Average: 240 W/m2 Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? • In balance at + 15 °C… On Average: 240 W/m2 Average: 240 W/m2 150 W/m2 sent back to Earth On Average: 390 W/m2 Australian Institute of Physics (Vic Branch) Education Committee What determines the Earth’s surface temperature? +15oC Greenhouse Warming 33 °C CO2 H2O –18oC Australian Institute of Physics (Vic Branch) Education Committee Amount of CO2 in the air over time 1.4 ppm per year 400 380 2 CO (ppm) With increasing CO2, more radiation is reflected back to earth, raising its temperature. 360 340 320 300 1960 1970 1980 1990 Year Australian Institute of Physics (Vic Branch) Education Committee 2000 2010 The Science of Climate Change: Explaining why we need to act NOW 1. The Earth’s atmosphere 2. Radiation and Greenhouse Effect 3. What is a Climate Model? 4. How has the climate already changed? 5. What do the models predict? Cause for concern 6. Expressing concern Australian Institute of Physics (Vic Branch) Education Committee Climate models are: Science-based tools for studying climate variability and change. They use mathematical representations of physical laws, including Newton's laws of motion, conservation of mass and energy, heat flow, and gas laws. They represent important processes in atmosphere, ocean, land surface and ice, as well as the coupling between them. There are more than twenty different models developed independently around the world. Australian Institute of Physics (Vic Branch) Education Committee Climate models: Specific factors Energy balance Water cycle Flow of air and water Australian Institute of Physics (Vic Branch) Education Committee Key components/processes of the climate system Energy balance – – – – – Incoming solar radiation Planetary movements Cloud reflection Aerosol/dust reflection Surface reflection and absorption Water cycle Flow of air and water Australian Institute of Physics (Vic Branch) Education Committee Key components/processes of the climate system Energy balance Water cycle – – – – – Evaporation Cloud formation Precipitation Interception by leaves and branches Runoff Flow of air and water Australian Institute of Physics (Vic Branch) Education Committee Key components/processes of the climate system Energy balance Water cycle Flow of air and water – – – – Air Pressure Circulation of air up and around - winds Circulation of water down and around - currents Effect of a rotating earth Australian Institute of Physics (Vic Branch) Education Committee IPCC AR4 WGI FAQ1.2 Fig 1 Australian Institute of Physics (Vic Branch) Education Committee FAQ 1.2, F Climate Models How do they work? The air and the oceans are broken up into cells. © Australian Bureau of Meteorology Australian Institute of Physics (Vic Branch) Education Committee Climate Models • The equations are applied to the cells of air and water to see how much air/heat flows between each pair of cells. • This is repeated all around the Earth. • The models have improved by making the cells smaller. • They are now about 110 km square by 1 km high. Australian Institute of Physics (Vic Branch) Education Committee Annual average rainfall Observations: 1980-99 Multi-model average: 1980-99 Australian Institute of Physics (Vic Branch) Education Committee What do models show? Black: Temperature measurements Red: Predictions by models assuming human factors such as CO2 emissions as well as natural ones such as sun cycles and volcanic eruptions. Australian Institute of Physics (Vic Branch) Education Committee What do models show? Black: Temperature measurements Blue: Predictions by models assuming only natural factors. WGI Fig TS.23 Australian Institute of Physics (Vic Branch) Education Committee Observed Temperature changes 1 Temperature Anomaly (Celsius) 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1 1850 1870 1890 1910 1930 1950 Year Australian Institute of Physics (Vic Branch) Education Committee 1970 1990 2010 The Science of Climate Change: Explaining why we need to act NOW 1. The Earth’s atmosphere 2. Radiation and Greenhouse Effect 3. What is a Climate Model? 4. How has the climate already changed? 5. What do the models predict? Cause for concern 6. Expressing concern Australian Institute of Physics (Vic Branch) Education Committee Germany Australian Institute of Physics (Vic Branch) Education Committee Muir Glacier, Alaska Other observations Photo credit: Global Warming Art Australian Institute of Physics (Vic Branch) Education Committee Argentina Australian Institute of Physics (Vic Branch) Education Committee Climate change impacts Greenland ice sheet The Greenland summer ice melt is getting larger at a worrying rate. Australian Institute of Physics (Vic Branch) Education Committee Human induced changes The Arctic Ice is melting at a much faster rate than predicted Australian Institute of Physics (Vic Branch) Education Committee Impact on the oceans CO2 is absorbed by the oceans, making them more acidic. This weakens marine skeletons. 8.3 8.2 8.1 pH 8 7.9 7.8 10 million 1 million years ago years ago Time 1850 1950 2050 1900 2000 2100 A change of 0.1 in pH is a 26% change in the acidity of the water. Australian Institute of Physics (Vic Branch) Education Committee The Science of Climate Change: Explaining why we need to act NOW 1. 2. 3. 4. The Earth’s atmosphere Radiation and Greenhouse Effect What is a Climate Model? How has the climate already changed? 5. What do the models predict? Cause for concern 6. Expressing concern Australian Institute of Physics (Vic Branch) Education Committee Annual warming for 2080-2099 17-model average Watterson and Arblaster (2005) Australian Institute of Physics (Vic Branch) Education Committee Australia Annual (b) Average of the change in temperature* by 2070 predicted by 15-models. Summer Autumn Winter Spring *relative to 1990. Temperature change oC Australian Institute of Physics (Vic Branch) Education Committee Emission scenarios Australian Institute of Physics (Vic Branch) Education Committee Emission scenarios A1FI An emphasis on Fossil-fuels (Intensive). A1B A Balanced emphasis on all energy sources. A1T Emphasis on non-fossil energy sources. Australian Institute of Physics (Vic Branch) Education Committee Scientists say that ‘2 degrees of warming is locked in’, but that is only the most likely outcome, … Tipping points 0.6 Greenland ice sheet Tibetan glaciers 0.5 Amazon rainforest Probability 0.4 El Nino Southern Oscillation 0.3 Thermohaline circulation 0.2 Arctic summer ice 0.1 West Antarctic ice sheet 0 0 1 2 3 4 5 6 Committed warming as of 2005 due to GHGs (degrees C) Australian Institute of Physics (Vic Branch) Education Committee 7 8 What the models show: Early and late 21st C Australian Institute of Physics (Vic Branch) Education Committee Australian Institute of Physics (Vic Branch) Education Committee Potentially vulnerable systems in Australia Vulnerable Drivers of change Impacts Economy Eastern Australian Alps Reduced precipitation & snow cover Shortened winter season. Loss of plant species, increased shrubs, less herbs Threats to built environment, biodiversity, ski industry viability/costs and tourism Eastern Queensland Coastal impacts of sea level rise, storm intensity Losses to infrastructure and coastal amenity Tourism implications. Infrastructure costs and insurance risk Kakadu Salt water intrusions Displacement of freshwater wetlands with mangroves Biodiversity and tourism implications Murray Darling Basin Reduced river flow Enhanced water competition for natural flows, irrigation and town water supplies Higher cost of water. Loss of agricultural production and biodiversity Queensland wet tropics Coastal impacts of sealevel rise & storm Intensity Species extinction, loss of coral reefs, coastal flooding and infrastructure damage Tourism implications. Infrastructure costs & insurance risk SW Western Australia Drying Water shortages, fragmentation of ecosystems Loss of agriculture production or enforced changes. Loss of biodiversity Sub Antarctica islands Warming & deglaciation Loss of key species and rapid changes to ecosystem assemblages Loss of biodiversity Australian Institute of Physics (Vic Branch) Education Committee Who’s vulnerable to climate change? Australian Institute of Physics (Vic Branch) Education Committee “This is not just an environmental problem. It is a defence problem. It is a problem for those who deal with economics and development, conflict prevention, agriculture, finance, housing, transport … trade and health”. UK Foreign Secretary, Margaret Beckett, Australian Institute of Physics (Vic Branch) Education Committee The Science of Climate Change: Explaining why we need to act NOW 1. 2. 3. 4. 5. The Earth’s atmosphere Radiation and Greenhouse Effect What is a Climate Model? How has the climate already changed? What do the models predict? Cause for concern 6. Expressing concern Australian Institute of Physics (Vic Branch) Education Committee Expressing concern Political Write and phone and fax and email and talk to your local members (State and Federal, upper and lower house). Advocate one or more of the following: • A maximum global CO2 level by 2020 (2050), e.g. 350 parts per million. • Zero emissions by Australia by, for example, 2050 • Carbon emissions tax with a tax rebate for low income earners • Subsidy of alternative fuels: including Geothermal, Solar Thermal, Wind, PV, Nuclear and Biomass from a carbon emissions tax . • Feed in tariffs for solar panels. Australian Institute of Physics (Vic Branch) Education Committee Expressing concern Personal Possible actions that you can do include: • Retrofit double glazing, • Adjust temperature settings of heating and cooling, • Put up pelmets, • Install compact fluorescents, • Use public transport, • Use throw rugs, • Install solar panels and a solar water heater. Australian Institute of Physics (Vic Branch) Education Committee Acknowledgements Australian Institute of Physics (Vic Branch) Education Committee