Geology 1350 Lecture 19 Outline of Last Lecture I. HurricanesII. Global climateOutline of Current Lecture I. Climate changeCurrent LectureWeather- short term fluctuations, temp, pressure, windspeed, wind direction can last hours days or weeks, specific location for specific timeClimate- longer term changes, broad composite of average condition of a region temp, rainfall, ice cover, winds, years and longer, mean state of specific region, continent, ocean , or entire planetClimate is always changing but major concerns for mankind are rapid changes within a short period of time concerns include:melting glaciers, water storage will disappear (droughts) problems with water energyrising sea level- due to melting glaciers and thermal expansion- impact on coastal areas (oftendensely populate)climate zone will shift in particular precipitation patterns monsoons will change – impact agriculture, on distribution of insects (included associated diseases)higher ocean surface temp, more and stronger tropical cycloneschanging ocean currents due to change in freshwater saltwater distributions, regional and large scale climate variations (gulf stream)time scales of climate change- These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.different time resolution- lake bottom sediments, pollen in ice caves, fossil evidence, coral isotopes, calcium carbonate layers in caves, borehole temp, dendrochronology or tree ring data, written documentsclimate is always changing- ice core records show that co2 values were about 180-280 ppmv for thousands of years until after 1800, o180 correlates with ice volume and ice volume correlates with co2 level in the atmosphere less ice when temperature are higher (higher co2 levels)ice core trend match well with atmospheric measurements started in 1958 at Mauna Loa by David Keelingcomponents of climate system- co2 can go into the soil, as well as oil, gas and coilgreenhouse effect- efficient water, prominent carbon dioxidepositive-feedback in the climate system- cooling more snow or ice cover and colder temps, warming less snow and ice cover higher tempsnegative- warming more h20 more clouds higher albedo, colder temps where clouds, h20 vapor is a greenhouse effectsea surface isotherms during august 18000 yr ago- estimated from analysis of ocean sediment cores that held temperature sensitive signatures such as sea shell content and oxygen-isotoperatios).Plate tectonics and drift concentrated continents at higher altitudes eventually more ice coverand reflected more sunlight and created a positive feedback to cause greater coolingTectonic processes associated with continental drift increased periods of volcanic degassing ofc02 which causes warmingHigher temperatures increases weathering removal of co2 from the atmosphere reverse warming in a negative feedback loopclimate change triggers- carbon dioxide fluctuationa)orbit eccentricity, from ellipse to circle at 100,000 year circlesb)wobble precession from the north pole pointing toward or away from the sun in july at 23,000 year circlesc)today tilt obliquity is 23.5 however tilt changes from 22 to 24.5 at 41,000 year cyclesother factors- amount of dust, reflectivity of ice sheets, concentration of greenhouse gases, characteristics of clouds, rebounding of landauto emissions and wild fires are two sources that emit aerosols into the troposphere reduction of incoming radiation and net cooling effect on earths surface as well as volcanic eruptionsvolcanic eruptions push aerosols into the stratosphere reduction of incoming radiation, net cooling effect on earths surface, large eruptions have been linked to significant episodesvolcano causes warmer temperature throughout years, sun spots- impact on climate as well as greenhouse gasesclimate models often test their skill by hind observed climate from 1860 to the presentmodels improved predictions as they became more sophisticated and included, greenhouse gases, aerosols, and changes in solar radiationClimate models predict that land areas will warm more rapidly than oceans, particularlyat northern high latitudes because Dark boreal trees absorbing three times more solar energy than the snow-covered tundra, warmer climate ,positive feedback of boreal forests to expanding their