3Climate Change Debate?“The major scientific agencies of the United States — including the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) — agree that climate change is occurring and that humans are contributing to it.” - EPA
4Questions Still Up For Debate Scientists are still researching a number of important questions:Exactly how much will Earth warm?How quickly will it warm?What will the consequences of the warming be in specific regions of the world?
5Global ChangeGlobal change: any chemical, biological, or physical property change of the planet (ex: cold temperatures causing ice ages)Global climate change: changes in the climate of the EarthGlobal warming: one aspect of climate change, the warming of the oceans, landmasses, and atmosphere of the Earth
7Greenhouse EffectWhen radiation from the sun hits the atmosphere, 1/3 is reflected backSome UV radiation is absorbed by the ozone layerSome strikes the Earth and is converted into low-energy infrared radiationInfrared radiation then goes back toward the atmosphere, where it’s absorbed by greenhouse gases that radiate most of it back to the Earth
10Global Warming Potential Certain GHGs are more effective at warming the Earth than others2 most important factors:How well the gas absorbs energyHow long the gas stays in the atmosphereGlobal Warming Potential (GWP) is a measure of the total energy that a gas absorbs over a particular period of time (usually 100 years), compared to CO2
19Particulate MatterAerosols are a subset of air pollution that refers to the tiny particles suspended in our atmosphereParticles can be both solid and liquidLight-colored aerosol particles can reflect incoming solar energyDark particles can absorb solar energy
21Radiative ForcingEnergy is constantly flowing into the atmosphere and being absorbed by EarthSome energy is always radiating back out into space (infrared light)If:Energy flowing out > energy flowing in = coolingEnergy flowing out < energy flowing in = warmingEnergy flowing out = energy flowing in = no change
22Radiative ForcingEnergy is constantly flowing into the atmosphere and being absorbed by EarthSome energy is always radiating back out into space (infrared light)If:Energy flowing out > energy flowing in = coolingEnergy flowing out < energy flowing in = warmingEnergy flowing out = energy flowing in = no change
23Radiative ForcingEnergy is constantly flowing into the atmosphere and being absorbed by EarthSome energy is always radiating back out into space (infrared light)If:Energy flowing out > energy flowing in = coolingEnergy flowing out < energy flowing in = warmingEnergy flowing out = energy flowing in = no change
24Radiative ForcingRadiative forcing is a direct measure of the impact that human activities are having on changing the planet’s climateMeasured in watts per square meter (W/m2) of surface
26IPCCThe Intergovernmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate changeEstablished in 1988 by two United Nations organizations: the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP)Its mission is to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impactsThousands of scientists and other experts contribute (on a voluntary basis) to writing and reviewing reports, which are reviewed by representatives from all the governments
27Increasing CO2 Concentrations David Keeling began measuring CO2 in 1958
28Comparing Emissions Which country emits the most CO2? Which country emits the most CO2 per capita?
31What do you think?Should developing countries be held to the same CO2 emissions standards as developed countries?Things to consider:How did developed countries become so wealthy?Which countries are to blame for climate change?Will strict CO2 standards inhibit growth in developing countries?Will developing countries be able to afford costly new technology?
32Global Temperature Change Since 1880, temperatures have increased 0.8°C
35Temperatures & Greenhouse Gas Concentrations in Past 400,000 Years No one was around thousands of years ago to measure temperatures, so we must use indirect measurementsChanges in species compositionChemical analysis of ice
36Ice CoresIce cores contain an abundance of climate information – more so than any other natural recorder of climate like tree rings or sediment layersAlthough their record is short (in geologic terms), it can be highly detailed and extend back hundreds of thousands of yearsThis record can include:TemperaturePrecipitationChemistry and gas composition of the lower atmosphereVolcanic eruptionsSolar variability
43Sediment CoresRarely disturbed ocean sediment cores can provide records up to 180 million years ago as new layers of sediment bury and preserve those of the pastFossilized specimens of microscopic foraminifera can provide clues to the climate conditions during their livesSome species are only found in certain environments, so we can reconstruct the sea level, ocean, and climate conditions of that period based on our knowledge of foraminifera species
44Oxygen IsotopesOcean water during warmer times has a lower 18O / 16O ratio than ocean water during colder timesForaminifera incorporate that oxygen into their shells (CaCO3), which accumulate on the ocean floor after they dieWe can estimate the water temperature by the ratio of 18O / 16O in fossilized shells
45Climate ModelsScientists use climate data gathered from the past to help predict the futureCurrent models predict that average global temperatures will increase 1.8⁰ – 4.0⁰ C (3.2⁰ – 7.2⁰ F) by 2100
50Positive Feedback Loop We know that an increase in CO2 in the atmosphere causes a greater capacity for warming through the greenhouse effectHigher temperatures warmer oceans oceans release CO2 gas into atmosphere
53AP Practice QuestionWhich statement about feedback loops that occur with climate change is true?All feedback loops are positive.All feedback loops are negative.Increased soil decomposition under warmer temperatures represents a positive feedback loop.Increased evaporation under warmer temperatures represents a negative feedback loop.Increased plant growth under higher CO2 concentrations represents a positive feedback loop.
54Consequences of Global Warming Melting of polar ice caps, Greenland, and AntarcticaMelting of glaciers around the worldMelting of permafrostRising sea levelsHeat waves and droughtsFewer cold spellsGreater frequency and intensity of storms
59Consequences to Living Organisms Changing growing season for plants can harm animals if they can’t move to better climatesHumans may have to relocateDiseases, like those carried by mosquitoes, could increaseEconomic consequences
60Controversy of Climate Change The fundamental basis of climate change (that greenhouse gas concentrations are increasing and that this will lead to global warming) is not in dispute among the vast majority of scientistsWhat is unclear is how much world temperatures will increase for a given change in greenhouse gases, because that depends on the different feedback loops
62Kyoto ProtocolIn 1997, representatives of the nations of the world went to Kyoto, Japan to discuss how best to control the emissions contributing to global warmingThe agreement was that emissions of greenhouse gases from all industrialized countries will be reduced to 5.2% below their 1990 levels by 2012Developing nations did not have emission limits imposed by the protocol
63Climate Change Awareness The Nobel Peace Prize 2007 was awarded jointly to Intergovernmental Panel on Climate Change (IPCC) and Albert Arnold (Al) Gore Jr. "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change"
64Carbon SequestrationAn approach involving taking CO2 out of the atmosphereSome methods include storing carbon in agricultural soils or retiring agricultural land and allowing it to become pasture or forestResearchers are looking at cost-effective ways of capturing CO2 from the air, from coal-burning power stations, and from other emission sourcesThis captured CO2 would be compressed and pumped into abandoned oil wells or the deep ocean
66AP Practice QuestionWhich statement regarding the Kyoto Protocol is true?Developed and developing nations all agreed to reduce their emission of greenhouse gasesAll nations agreed to stop their emission of greenhouse gasesThe developed nations agreed to different levels of emission reductionsDeveloping nations agreed to reduce their emission of greenhouse gasesDeveloping nations agreed to stop their emission of greenhouse gases
67What Do You Think? What is the best way to reduce CO2 emissions? Force people and companies to be more energy efficient and/or to use “green” technologiesORAllow people and companies to pollute as much as they want, but tax them on how much CO2 they emit