GEOL 101 1nd Edition Lecture 26 Outline of Last Lecture I Atmospheric Heating II Natural Climate Change III Anthropogenic Climate Change Outline of Current Lecture I Consequences of Climate Change a Climate Belts b Melting of Permafrost c Desertification increased droughts and wildfires d Retreat glaciers e Sea level rising f Stronger storms and hurricanes g Changes in oceanic currents h Ocean acidification II The Changing Future Current Lecture We ve seen that the earth its spheres and their connections are intricate and complex Predicting the resulting consequences of climate change is difficult because there are so many factors but we can rely on what we know of past climate change to predict some of the likely outcomes Shifts in Climate belts Melting of Permafrost Desertification increased droughts and wildfires Retreat glaciers Sea level rising Stronger storms and hurricanes Changes in oceanic currents Ocean acidification Climate Belts 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 Shifts in climate belts As climate warms we can expect to see climate belts shift to higher latitudes More temperate conditions in Polar Regions Pine Bark Beetle epidemic moving northward More arid desert conditions in temperate region Desertification of the Sand Hills Similar Miocene or Oligocene climate 4 6 C warmer than present Shifting climate belts can be seen in agricultural Plant hardiness is an indication of the earliest date in a year when crops can be planted The zones are moving North Why can t agricultural zones simply shift north also Political At some point we lose assets to Canada Geological The last ice age scraped off much of the top soil and sediment in Northern regions and deposited that material in Midwest Much of Canada is underlain by the Canadian Shield exposed igneous and metamorphic rock covered by a thin layer of topsoil not great for agriculture Desertification Desertification increasing drought and wildfires warming climates and shifting climate zones may result in current semi arid steppe regions becoming more arid Primary areas at risk Central western US Eastern Europe Middle East Most of Africa Many of these areas are used for agriculture Drier climates across larger regions increase the likelihood of droughts and wildfires Desertification reduces vegetation exposing topsoil to erosion Glaciers Retreat of glaciers One of the most visible results of warming climates is the retreat of glaciers up valley and the shrinking of polar sea ice Produces a feedback loop with albedo and reflectivity less reflecting reinforces warming Higher snowline elevations Less winter snowpack less summer snowmelt Drought in alpine region forest fires Shorter ski seasons Permafrost Melting of permafrost soil that stays at or below freezing for two or more years tundra soils As climate warms permafrost soil melts Results in slumping and subsidence of the land Thawing of organic carbon which will decompose Release methane and CO2 in the atmosphere Sea Level Sea level rise as glacial ice melts sea level will rise Average thickness of the Antarctica ice sheet 7 000 feet Average thickness of the Greenland ice sheet 6 000 feet 170 000 alpine glaciers worldwide Permafrost soil across northern Canada Scandinavia and Siberia Sea level would rise over 200 feet if all ice were to melt The last time the earth was completely ice free was 65 Ma Research indicates that sea level has risen 4 8 inches in the last 100 years Present models predict sea level to be 2 ft higher by 2100 Coastlines bayous and wetlands would be most directly affected Storms and Hurricanes Stronger storms and hurricanes form as low pressure centers move across warm water picking up energy from evaporating water Hurricanes form as low pressure centers more across warm water picking up energy from evaporating water The energy involved in producing water vapor from liquid water is enormous The wind energy of an average hurricane is the equivalent of 31 megatons of TNT or 2 066 atomic bombs per day The latent heat energy released by condensing water vapor into rain is the equivalent of 12 460 megatons of TNT or 830 000 atomic bombs Stronger storms and hurricanes Warmer ocean temperature lead to more evaporation which will more readily fuel pressure centers We may see an increase in the number of hurricanes and or the intensity of hurricanes We may also see stronger and or more frequent thunderstorms and tornado outbreaks Higher temperatures more evaporation leave more moisture in the air Thunderstorms form as cold dry air masses meet warm air masses This may also eventually reduce the severity of thunderstorms if temperatures rise enough in polar regions Ocean Currents Changes in ocean currents Oceanic circulations is primarily driven by density differences in the water Thermohaline temperature and salinity Warm less salty water is more buoyant Cold saltier water is more dense Surface circulation is mainly driven by wind Gulf Stream N Atlantic Current EAC etc Melting polar ice caps dilutes the salinity of sea water at the poles potentially altering global circulation patterns Warming water may change circulation patterns as well Ocean Acidification CO2 from the atmosphere dissolves into sea water CO2 combines with H2O to form carbonic acid H2CO3 Carbonic acid dissolves calcium carbonate CaCO3 Higher levels of CO2 in the atmosphere result in more CO2 being dissolved in sea water more carbonic acid and higher ocean acidity Many marine organisms make their shells and skeletons out of CaCO3 corals mollusks sponges snails plankton Ocean acidification threatens many marine ecosystems We have already seen a measureable change in ocean pH from pre Industrial Revolution levels 8 179 to present day levels 8 069 Projected levels by 2050 7 949 Changing Future Numerous lines of evidence show that the planet s climate is warming there is no longer any doubt whether or not anthropogenic changes to the land and atmosphere are a major factor Predicting future outcomes is difficult because of the numerous and complex interactions between the atmosphere hydrosphere cryosphere biosphere and geosphere Anthropogenic disruption shifts into a new equilibrium Permian like mass extinction event Somewhere in between The future essentially depends on the decisions we make in the present