Chapter 16 The Oceans and Climate Change What Comprises Earth s Climate system Climate defined as the conditions of Earth s atmosphere including temperature precipitation and win that characteristically prevail in a particular region over extended time spans Earth s climate is a complex and interacting system that includes five spheres atmosphere hydrosphere geosphere biosphere and cryosphere Climate system involves the exchanges of energy and moisture that occur among the five spheres the changes link all the spheres so they can interact as a unit Feedback loops processes that modify initial changes Positive feedback loop has an amplifying effect that fortified or adds to an initial change A produces more of B which in turn produces more of A Negative feedback loop diminishing effect that tends to counteract or subtract from an initial change A produces more of B which in turn produces LESS of A Determining Earth s Past Climate changes in Earth s climate Climate scientist use three closely connected methods to understand o They look at geologic evidence and other records of Earth s past climates to see how and why climate changed in the past o They build computer models that allow them to see how the climate works o They closely monitor Earth s current vital signs with an array of instruments including historical records ships data deep sea thermometers and data from space based satellites Proxy data that comes from natural recorders of climate Ex Tree growth rings sea floor sediments trapped air bubbles in the annual layers of glacial ice fossil pollen coral reefs cave deposits and historical documents Paleoclimatology scientists who analyze proxy data and reconstruct past climates main goal is to understand Earth s past climate in order to gain insight into Earth s current climate and future climate Natural Causes of Climate Change Changes in Solar Energy the Sun s output of energy could be changing over time Variations in Earth s orbit changes in the shape of the orbit variations in the angle that Earth s axis makes with the plane of its orbit wobbling of the axis cause fluctuations in the seasonal and altitudinal distribution of solar radiation reaching Earth Volcanic Eruptions volcanic eruptions emit huge quantities of gases and fine grained debris into the atmosphere the gases can remain in the atmosphere for a long period of time Movement of Earth s tectonic plates As landmasses move they shift ocean circulation altering the transport of heat and moisture and consequently the climate Today there is a clear scientific consensus that human induced emissions are responsible for the observed warming on Earth IPCC Intergovernmental Panel on Climate Change worldwide group of atmospheric and climate scientists that began studying the human effects on climate change and global warming What causes the atmosphere s greenhouse effect Global warming the increase in world wide temperature Greenhouse effect a natural process that influences the temperature of Earth s surface and atmosphere it is now being altered by human emissions a phenomenon that is often referred to as the anthropogenic greenhouse load or the enhanced greenhouse effect Earth s Heat Budget and Changes in Wavelength Heat budget describes all the ways in which heat is added to and subtracted from Earth In the upper atmosphere most solar radiation within the visible spectrum penetrates the atmosphere to Earth s surface like sunlight coming through greenhouse glass After scattering by atmospheric molecules and reflection off clouds about 47 of the solar radiation that is directed toward Earth is absorbed by the oceans and continents About 23 is absorbed by the atmosphere and clouds and about 30 is reflected into space by atmospheric backscatter clouds and Earth s surface Gases that contribute to greenhouse gases Water Vapor single most important absorber of heat Carbon Dioxide human caused gas makes the greatest relative contribution to increasing the greenhouse effect Methane 2 most abundant human caused greenhouse gas produced from leakage of decomposing trash methane belching domestic cattle agriculture Documented changes occurring because of global warming Melting glaciers and ice caps shorter winters shifts in species distribution and a steady rise in average global and sea surface temperatures are just some of the indications that additional human induced greenhouse warming is occurring Ocean temperatures are rising Increased Hurricane Activity Changes in Deep Water Circulation Melting of Polar Ice Recent Increase in Ocean Acidity 1 3 of the carbon dioxide released into the atmosphere ends up in the oceans This reduces global warming but acidifies the sea overwhelming the oceans natural buffering system Rising sea level melting of ice thermal expansion of ocean surface waters thermal expansion of deep ocean waters Possible questions with answers Of the following which are components of Earth s climate system o All of the above Biosphere Atmosphere Cryosphere Geospher Hydrosphere Of the following which are examples of climate feedback loops o All of the above heat uptake by the oceans he addition of water vapor into the atmosphere the presence of fine atmospheric particles called aerosols the shading effect from air pollution the role of clouds at different altitudes Of the following which are useful as proxy data for understanding past climate changes o All Tree growth rings sea floor sediments annual layers of snow packed in glacial ice historical documents fossil pollen Of the following natural factors which have caused past climate changes on Earth o The movement of Earth s tectonic plates changes in solar energy volcanic eruptions variations in Earth s orbit The warming of Earth s surface and atmosphere is a natural process controlled by the greenhouse effect It is also being altered by human emissions a phenomenon that is often referred to as o The anthropogenic greenhouse load the enhanced What are the main factors that contribute to the documented greenhouse effect global rise in sea level o Thermal expansion of ocean water as it warms and an increase in the amount of water in the ocean from the melting of ice on land Of the following which ocean changes are predicted to result from global warming o Increased transmission distance of sound in the sea increase in ocean stratification and the development of a stronger thermocline migration of marine organisms into deeper waters and toward the poles lower
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