GEOL 1301 Fall 2014 Lecture 20Outline of Last Lecture I. Climate Systems (cont.)Outline of Current LectureII. Climate Systems (cont.)CLIMATERecordModernInstrumental temperature record of the last 150 yearsSee also: Instrumental temperature record and Satellite temperature measurementsDetails of the modern climate record are known through the taking of measurements from such weatherinstruments as thermometers, barometers, and anemometers during the past few centuries. The instruments used to study weather over the modern time scale, their known error, their immediate environment, and their exposure have changed over the years, which must be considered when studyingthe climate of centuries past.[40]PaleoclimatologyMain article: PaleoclimatologyPaleoclimatology is the study of past climate over a great period of the Earth's history. It uses evidence from ice sheets, tree rings, sediments, coral, and rocks to determine the past state of the climate. It 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.demonstrates periods of stability and periods of change and can indicate whether changes follow patterns such as regular cycles.[41]Climate changeVariations in CO2, temperature and dust from the Vostok ice core over the past 450,000 yearsSee also: Climate change, Global warming, Temperature record and Attribution of recent climate changeClimate change is the variation in global or regional climates over time. It reflects changes in the variability or average state of the atmosphere over time scales ranging from decades to millions of years.These changes can be caused by processes internal to the Earth, external forces (e.g. variations in sunlight intensity) or, more recently, human activities.[42]In recent usage, especially in the context of environmental policy, the term "climate change" often refers only to changes in modern climate, including the rise in average surface temperature known as global warming. In some cases, the term is also used with a presumption of human causation, as in the United Nations Framework Convention on Climate Change (UNFCCC). The UNFCCC uses "climate variability" for non-human caused variations.[43]Earth has undergone periodic climate shifts in the past, including four major ice ages. These consisting ofglacial periods where conditions are colder than normal, separated by interglacial periods. The accumulation of snow and ice during a glacial period increases the surface albedo, reflecting more of theSun's energy into space and maintaining a lower atmospheric temperature. Increases in greenhouse gases, such as by volcanic activity, can increase the global temperature and produce an interglacial. Suggested causes of ice age periods include the positions of the continents, variations in the Earth's orbit, changes in the solar output, and volcanism.[44]Climate modelsSee also: Climate models and ClimatologyClimate models use quantitative methods to simulate the interactions of the atmosphere,[45] oceans, land surface and ice. They are used for a variety of purposes; from the study of the dynamics of the weather and climate system, to projections of future climate. All climate models balance, or very nearly balance, incoming energy as short wave (including visible) electromagnetic radiation to the earth withoutgoing energy as long wave (infrared) electromagnetic radiation from the earth. Any imbalance results in a change in the average temperature of the earth.The most talked-about applications of these models in recent years have been their use to infer the consequences of increasing greenhouse gases in the atmosphere, primarily carbon dioxide (see greenhouse gas). These models predict an upward trend in the global mean surface temperature, with the most rapid increase in temperature being projected for the higher latitudes of the Northern Hemisphere.Models can range from relatively simple to quite complex:Simple radiant heat transfer model that treats the earth as a single point and averages outgoing energythis can be expanded vertically (radiative-convective models), or horizontallyfinally, (coupled) atmosphere–ocean–sea ice global climate models discretise and solve the full equations for mass and energy transfer and radiant exchange.[46]Climate forecasting is a way by some scientists are using to predict climate change. In 1997 the prediction division of the International Research Institute for Climate and Society at Columbia University began generating seasonal climate forecasts on a real-time basis. To produce these forecasts an extensive suite of forecasting tools was developed, including a multimodel ensemble approach that required thorough validation of each model's accuracy level in simulating interannual climate