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Image courtesy of NASA/GSFC. Global Environmental Change: Technology and the Future of Planet Earth. Eugene S. Takle Professor Department of Agronomy Department of Geological and Atmospheric Science Director, Climate Science Program Iowa State University Ames, IA 50011.
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Image courtesy of NASA/GSFCGlobal Environmental Change: Technology and the Future of Planet EarthEugene S. TakleProfessor Department of AgronomyDepartment of Geological and Atmospheric ScienceDirector, Climate Science ProgramIowa State UniversityAmes, IA 50011Technology, Globalization, and CultureME/WLC 484Ames Iowa29 August 2012Climate change is one of the most important issues facing humanityThe scientific evidence clearly indicates that our climate is changing, and that human activities have been identified as a dominant contributing cause.Don WuebblesOutline
  • Scientific evidence for global climate change
  • Changes in Iowa
  • Impacts of climate change on Iowa agriculture
  • Alternative projections of climate futures
  • The need for long-term mitigation that starts now
  • Climate changes are underway in the U.S. and are projected to growTemperature riseSea-level riseIncrease in heavy downpoursRapidly retreating glaciersThawing permafrostLengthening growingseasonLengthening ice-free seasonin the ocean and on lakesand riversEarlier snowmeltChanges in river flowsPlants blooming earlier; animals, birds and fish moving northwardDon WuebblesThree separate analyses of the temperature record – Trends are in close agreement2010 tied 2005 as the warmest year on record since 1880Temperature Changes are Not Uniform Around the GlobeFrom Tom Karl, NOAA NCDCU.S. Temperature TrendsU.S. average temperature has risen more than 2oF over the past 50 yearsFrom Tom Karl, NOAA NCDCConditions today are unusual in the context of the last 2,000 years …Don WuebblesWhy does the Earth warm?1. Natural causesTHE GREENHOUSE EFFECT…
  • …is 100% natural.
  • Heat is trapped in the atmosphere.
  • …sustains life on Earth.
  • Keeps average temperatures at 12.8oC (55oF), instead of –29oC (-20oF).
  • Don WuebblesWhy does the Earth warm?2. Human causesTHE ENHANCED GREENHOUSE EFFECT(or GLOBAL WARMING)
  • … is primarily human-induced: We’re increasing heat-trapping gases in the atmosphere.
  • … is like wrapping an extra blanket around the Earth.
  • Don WuebblesNatural factors affect climateVariations in the energyreceived from the sunVariations in the Earth's orbit(Milankovic effect)Stratospheric aerosols fromenergetic volcanic eruptionsChaotic interactions inthe Earth's climate(for example, El Nino, NAO)Don WuebblesNon-natural mechanisms
  • Changes in atmospheric concentrations ofradiatively important gases
  • Changes in aerosol particles from burning fossil fuels and biomass
  • Changes in the reflectivity (albedo) of the Earth’s surface
  • Don WuebblesWarming of the Lower and Upper Atmosphere Produced by Natural and Human CausesKarl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.Warming of the Lower and Upper Atmosphere Produced by Natural and Human CausesNote that greenhouse gases have a unique temperature signature, with strong warming in the upper troposphere, cooling in the lower stratosphere and strong warming at the surface over the North Pole. No other warming factors have this signature. Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.Warming of the Lower and Upper Atmosphere Produced by Natural and Human CausesNote that greenhouse gases have a unique temperature signature, with strong warming in the upper troposphere, cooling in the lower stratosphere and strong warming at the surface over the North Pole. No other warming factors have this signature. Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.Warming of the Lower and Upper Atmosphere Produced by Natural and Human CausesNote that greenhouse gases have a unique temperature signature, with strong warming in the upper troposphere, cooling in the lower stratosphere and strong warming at the surface over the North Pole. No other warming factors have this signature. Climate models: Natural processes do not account for observed 20th century warming after 1965Don WuebblesWe have Moved Outside the Range of Historical Variation800,000 Year Record of Carbon Dioxide ConcentrationDon WuebblesWhat can we expect in the future?Don WuebblesIPCC 2007December-January-February Temperature Change7.2oF6.3oFA1B Emission Scenario2080-2099 minus1980-1999IPCC 2007June-July-August Temperature Change4.5oF5.4oFA1B Emission Scenario2080-2099 minus1980-1999Increases in very high temperatures will have wide-ranging effectsHigher Emissions Scenario, 2080-2099Number of Days Over 100ºFAverage:30-60 daysRecent Past, 1961-1979Lower Emissions Scenario, 2080-2099Average:10-20 daysDon WuebblesIncreases in very high temperatures will have wide-ranging effectsHigher Emissions Scenario, 2080-2099Number of Days Over 100ºFAverage:30-60 daysRecent Past, 1961-1979Current Des Moines average is < 1.4 days per year over 100oFLower Emissions Scenario, 2080-2099Average:10-20 daysDon WuebblesProjected Change in Precipitation: 2081-2099Midwest: Increasing winter and spring precipitation, with drier summersMore frequent and intense periods of heavy rainfallUnstippled regions indicate reduced confidence Relative to 1960-1990NOTE: Scale ReversedDon WuebblesExtreme weather events become more common
  • Events now considered rare will become commonplace.
  • Heat waves will likely become longer and more severe
  • Droughts are likely to become more frequent and severe in some regions
  • Likely increase in severe thunderstorms (and perhaps in tornadoes).
  • Winter storm tracks are shifting
  • northward and the strongest storms are likely to become stronger and more frequent.Don WuebblesChange in Growing Season Precipitation for IowaNo changeCJ Anderson, ISUFuture Variability in Growing Season Precipitation for IowaMore extreme floodsMore extreme droughtsCJ Anderson, ISUProjected Changes in Mean Precipitation in the US MidwestUS global climate models(higher flood potential)Precipitation Change (%)Zero changeTemperature Change (oC)Non-US global climate models(higher drought potential)CJ Anderson, ISU1 meter will be hard to avoid, possibly within this century, just from thermal expansion and small glacier melt.Don WuebblesWidespread climate-related impacts are occurring now and are expected to increaseWater ResourcesEnergy Supply & UseTransportationAgricultureEcosystemsHuman HealthSocietyDon WuebblesFirst Date Iowa’s Average Fall 4-inch Soil Temperature Was Below 50oFIowa Environmental Mesonet2010 Des Moines Airport DataCaution: Not corrected for urban heat island effectsDes Moines Airport DataCaution: Not corrected for urban heat island effectsIowa State-Wide Average DataDes Moines Airport Data8 days in 20121983: 131988: 101977: 86 days ≥ 100oF in the last 22 yearsSummer (JJA) Cloud Cover, Des MoinesIowa State-Wide Average DataIowa State-Wide Average Data34.0”10% increase30.8”Iowa State-Wide Average DataTotals above 40”2 yearsIowa State-Wide Average DataTotals above 40”8 years2 yearsCedar Rapids DataCedar Rapids Data32% increase28.0”37.0”Cedar Rapids DataYears with more than 40 inches132% increase28.0”37.0”Cedar Rapids DataYears with more than 40 inches11132% increase28.0”37.0”“One of the clearest trends in the United States observational record is an increasing frequency and intensity of heavy precipitation events… Over the last century there was a 50% increase in the frequency of days with precipitation over 101.6 mm (four inches) in the upper midwestern U.S.; this trend is statistically significant “Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.Cedar Rapids Data1.25 inches6.6 days4.2 days57% increaseCedar Rapids Data1.25 inchesYears having more than 8 days1326.6 days4.2 days57% increaseAmplification of the Seasonality of PrecipitationSpringFallWinterSummerAmplification of the Seasonality of PrecipitationSpringFallWinterSummerAmplification of the Seasonality of PrecipitationSpringFallWinterSummerAmplification of the Seasonality of PrecipitationSpringFallWinterSummerAmplification of the Seasonality of PrecipitationSpringFallWinterSummerAmplification of the Seasonality of PrecipitationSpringFallWinterSummerAmplification of the Seasonality of PrecipitationSpringFallWinterSummerAmplification of the Seasonality of PrecipitationSpringFall21.2 => 25.3 inches (22% increase)12.1 => 10.5 inches (13% decrease)WinterSummerIowa Agricultural Producers’ Adaptations to Climate Change
  • Longer growing season: plant earlier, plant longer season hybrids, harvest later
  • Wetter springs: larger machinery enables planting in smaller weather windows
  • More summer precipitation: higher planting densities for higher yields
  • Wetter springs and summers: more subsurface drainage tile is being installed, closer spacing, sloped surfaces
  • Fewer extreme heat events: higher planting densities, fewer pollination failures
  • Higher humidity:more spraying for pathogens favored by moist conditions. more problems with fall crop dry-down, wider bean heads for faster harvest due to shorter harvest period during the daytime.
  • Drier autumns:delay harvest to take advantage of natural dry-down conditions
  • HIGHER YIELDS!!Is it genetics or climate? Likely some of each.Why Small Changes in Rainfall Produce Much More Flooding
  • 13% increase in atmospheric moisture in June-July-August
  • ~10% increase in average precipitation in Iowa
  • ~5-fold increase in high-precipitation events, mostly in June-July-August, that lead to runoff
  • Iowa rivers and watersheds are oriented NW-SE
  • Rainfall patterns turn from SW-NE in March-May to W-E or NW-SE in mid summer
  • More frequent floods are the result of one or more of the following
  • More rain
  • More intense rain events
  • More rain in the summer
  • Rainfall patterns more likely to align with streams and watersheds
  • Streams amplify changes in precipitation by a factor of 2-4
  • AND: more subsurface drainage tile has been installedClimate trends of the recent past have low statistical significance. Nevertheless, they have forced significant agricultural and societal adaptation:Climate trends of the recent past have low statistical significance. Nevertheless, they have forced significant agricultural and societal adaptation:Even climate trends of low statistical significance can have impacts of high agricultural and societal significanceRise in global mean temperature (oC)Rise in global mean temperature (oC)Energy intensiveBalanced fuel sourcesMore environmentally friendlyLimit to avoid “dangerous anthropogenic Interference” with the climate system2oC limitIPCC Fourth Assessment Report Summary for Policy MakersLong-Term Stabilization ProfilesA2B1Nebojša Nakićenović IIASA, ViennaLong-Term Stabilization ProfilesA2Achieving this emission reduction scenario will provide a 50% chance of not exceeding the 2oC guardrailB1Nebojša Nakićenović IIASA, Vienna“Big Fixes” for ClimateUCAR Quarterly , Fall 2006
  • Sprinkle iron dust in the polar oceans
  • Inject large amounts of sulfate aerosol into the stratosphere
  • Launch saltwater spray to modify marine stratus clouds
  • Position 16,000,000,000,000 transparent, sunlight-refracting shades that would be deployed at the inner Lagrangian point of gravitational balance, about 1.5 million km from Earth toward the Sun. 20 launchers would each need to loft 800,000 screens every five minutes for ten years.
  • Illustration courtesy John MacNeillBig Fixes for Climate UCAR Quarterly Fall 2006A few of the 16 trillion sunlight-refracting shades proposed for deployment. Each mirror would span less than a square meter. The use of refraction rather than reflection would diminish sunlight-induced pressure from that would otherwise shift the shades' orbit. (Image courtesy of Roger Angel, UA Steward Observatory.)Summary
  • Global temperature trends of the 20C cannot be explained on the basis of natural variation alone
  • Only when the influences of greenhouse gases and sulfate aerosols are included can the trends be explained
  • Models that explain these trends, when projected into the future, indicate a 1.5-6.5oC warming over the 21C
  • Substantial adverse consequences to sea-level rise, food production, fresh-water supplies, severe weather events, and human health will occur for temperature increases above 2oC
  • “Big Fixes” have big negative side effects
  • For More Information
  • Contact me directly:
  • gstakle@iastate.edu
  • Current research on regional climate and climate change is being conducted at Iowa State University under the Regional Climate Modeling Laboratory
  • http://rcmlab.agron.iastate.edu/
  • North American Regional Climate Change Assessment Program
  • http://www.narccap.ucar.edu/
  • For current activities on the ISU campus, regionally and nationally relating to climate change see the Climate Science Initiative website:
  • http://climate.engineering.iastate.edu/Or just Google Eugene TakleCarbon Dioxide and Temperature2012390 ppm
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