Geography 5 Week 8 Lecture 1305-22-12The Science and Politics of Global WarmingEarth-Sun RelationsRecent solar output variation too small to account for current climate changesBut, has increased 25% over the last 4 billion yearsMilankovitch cyclesVariations in the Earth’s orbit p lay a role in determining [medium-term] climatic patternsAxial tiltChanges from 22.1° to 24.5° on a 41,000 year-cycleAxial precession26,000 year cycleGyroscopic motionEarth’s AlbedoAtmospheric interferenceClouds, dust can reflect solar radiation and lead to coolingEarth’s surfaceIce and high albedo surfaces reflect solar radiationsThe Green House EffectRadiation wavelengthsHotter objects emit shorter wavelengthsSolar (shorter) v. terrestrial radiation (longwave)The atmosphere and Green House Gasses [GHGs]Water Vapor, Carbon Dioxide [CO2], Methane [CH4], Nitrous Oxide [N20], Ozone [03]GHGs let in short-wave radiation, trap long-wave radiationGHGs contribute to the greenhouse effectWater vapor 36-72%CO2 9-26%Methane 4-9% [very potent]Ozone 3-7%Where does it come from?Break up of PangaeaBiological process in low oxygen environments [swamps]Release methaneBurning fossil fuels; natural firesAnimal husbandry/ agricultureField and forest clearing [burning]Carbon dioxide “sinks”Plants (via photosynthesis)The oceanReport by the intergovernmental panel on climate change [2007]Global scientific community consensusRising temperatures’95-06 among the warmest in the instrumental record (since 1850; industrial revolution)Most drastic temperature changes will be in arctic because of the ice melting [lowers the albedo]Arctic melting faster than the Antarctic because the arctic is on top of waterCause of Recent Climate Change [IPCC, 2007]“Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in the anthropogenic GHG concentration” [‘very likely=95%]Observed increase in CO2 ConcentrationsIncreases in release of Carbon Emission from Fossil Fuel burningSome Measureable Impacts [IPCC, 2007]Rises in global average sea level [IPCC, 2007]1.8 mm/yr. [1961-‘93]3.1mm/yr. [’93-present]decrease in icePositive feed-back systems may accelerate Climate ChangeEx: Ice Cap MeltingHigher temp melting ice  reduced albedo  greater absorption of energy higher temperatureE.g. melting permafrostDecay of peat moss releases methaneIPCC Report FlawsE.g. claimed Himalayan Glaciers will disappear by 2035Since withdrawn, admitted not adequately peer-reviewedImpacts of Global Warming on CASea level rises [flooding of coastal areas with populations]One meter rise in the bay area region33 and 55 inch rises in seal beach/Huntington beach areaSaltwater intrusion into coastal aquifersReduced snowpack, earlier snowmeltIncreased evapotranspirationReduced reservoirsIncrease water necessary for agriculture, landscapingShifting of vegetative communitiesGreater likely-hood of prolonged droughtsWildfire increaseHigher stream and reservoir temperatures and habitat changeIncreased demand for energy [air conditioning]Geography 5 Week 8 Lecture 1305-22-12The Science and Politics of Global Warming Earth-Sun Relations- Recent solar output variation too small to account for current climate changeso But, has increased 25% over the last 4 billion years- Milankovitch cycleso Variations in the Earth’s orbit p lay a role in determining [medium-term] climatic patterns o Axial tilt Changes from 22.1° to 24.5° on a 41,000 year-cycleo Axial precession 26,000 year cycle Gyroscopic motion o Earth’s Albedo Atmospheric interference Clouds, dust can reflect solar radiation and lead to cooling Earth’s surface Ice and high albedo surfaces reflect solar radiations The Green House Effect- Radiation wavelengthso Hotter objects emit shorter wavelengthso Solar (shorter) v. terrestrial radiation (longwave)- The atmosphere and Green House Gasses [GHGs]o Water Vapor, Carbon Dioxide [CO2], Methane [CH4], Nitrous Oxide [N20], Ozone [03]o GHGs let in short-wave radiation, trap long-wave radiationo GHGs contribute to the greenhouse effect Water vapor 36-72% CO2 9-26% Methane 4-9% [very potent] Ozone 3-7%o Where does it come from? Break up of Pangaea Biological process in low oxygen environments [swamps] Release methane  Burning fossil fuels; natural fires Animal husbandry/ agriculture  Field and forest clearing [burning] Carbon dioxide “sinks” Plants (via photosynthesis)  The ocean  Report by the intergovernmental panel on climate change [2007]- Global scientific community consensus- Rising temperatureso ’95-06 among the warmest in the instrumental record (since 1850; industrial revolution)o Most drastic temperature changes will be in arctic because of the ice melting [lowers the albedo]  Arctic melting faster than the Antarctic because thearctic is on top of water Cause of Recent Climate Change [IPCC, 2007]- “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in the anthropogenic GHG concentration” [‘very likely=95%] - Observed increase in CO2 Concentrations - Increases in release of Carbon Emission from Fossil Fuel burning  Some Measureable Impacts [IPCC, 2007]- Rises in global average sea level [IPCC, 2007]o 1.8 mm/yr. [1961-‘93]o 3.1mm/yr. [’93-present]- decrease in ice Positive feed-back systems may accelerate Climate Change- Ex: Ice Cap Meltingo Higher temp melting ice  reduced albedo  greater absorption of energy higher temperature o E.g. melting permafrost Decay of peat moss releases methane  IPCC Report Flaws- E.g. claimed Himalayan Glaciers will disappear by 2035o Since withdrawn, admitted not adequately peer-reviewed Impacts of Global Warming on CA- Sea level rises [flooding of coastal areas with populations]o One meter rise in the bay area regiono 33 and 55 inch rises in seal beach/Huntington beach areao Saltwater intrusion into coastal aquiferso Reduced snowpack, earlier snowmelt o Increased evapotranspiration Reduced reservoirs Increase water necessary for agriculture, landscaping o Shifting of vegetative communities o Greater likely-hood of prolonged droughts o Wildfire increaseo Higher stream and reservoir temperatures and habitat change- Increased demand for energy [air