Bio_Sc 1010 1st Edition Lecture 22Outline of Last Lecture I. EcosystemII. ClimateIII. Nitrogen Outline of Current Lecture I. Earth’s atmosphereII. The greenhouse effectIII. The carbon cycleIV. EnvironmentV. Global warming Current LectureEarth’s Atmosphere • Atmosphere: the layer of gases around the earth• The lowest layer, most gases• Ozone in the uppermost, screens out UVThe Greenhouse Effect• Gases in the atmosphere act like glass panels reflecting heat back to earth• CO2, methane, nitrous oxide, fluorocarbons, waterThe Carbon Cycle• Carbon is part of the backbone of all organic molecules• Carbon also exists in inorganic forms-carbon dioxide in the atmosphere -carbonic acid dissolved in water-calcium carbonate in limestone rocksThese 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.• Carbon enters the living world as CO2 via plants, algae, and bacteria that use it to perform photosynthesis• Animals get their carbon from photosynthesizers• The carbon moves back into the nonliving world as carbon dioxide, produced naturally through:-respiration-decomposition • Dead organisms fossilized before decomposing trap carbon below the earth’s surface or under the seas• Over time, these compressed organic molecules turn into fossil fuels – carbon rich energy sources, such as coal, oil, and natural gas • The total amount of carbon on earth remains essentially constant• As carbon cycles through the environment, it moves between organic and inorganic forms • Scientists use ice cores to measure biological and atmospheric conditions from the distant past • Gas bubbles present in the ice reveal the atmospheric composition thousands of years ago • Atmospheric carbon dioxide concentrations are higher now than they have been in more than 700,000 years• Carbon dioxide makes up a small (,035%) but critical proportion of the earth’s atmosphere• It is vital to life and greatly affects global climate Environment• Carbon footprint: a measure of the total greenhouse gases we produce by our activities • Global climate change – CO2-CO2 has been increasing since industrialization-deforestation – primarily of tropical forests: puts CO2 into the atmosphere directly through burning and results in less CO2 removed from the atmosphere -the earth’s atmospheric temperature is increasing-past 100 years, increased by 0.74 C or 1.3 F• Global climate change consequences-less snow cover globally affects albedo-less meltwater affects drinking water and sea level -rise in sea levels (Carteret Islands)-more intense tropical storms-CO2 increases plant productivity, but short lived-spread of disease (malaria, cholera)-increase in allergens-recreation (skiing) • Global change solutions-intergovernmental panel on climate change warns that changes now will not help that muchCarbon sinks and carbon sequestration• Species respond in many ways to temperature, one of the factors that govern climate-cellular effects: enzyme activity, membrane composition-organism effects: sex determination, activity patterns Global Warming• Sustainability: the use of the earth’s resources in a way that will not permanently destroy or deplete them-sustainability is living within the limits of earth’s bio capacity• Ecological footprint is a measure of how much land and water area is required to supply the resources a person or population consumes• As the human population grows, so does our environmental impact• Not everyone uses resources to the same extent • While many renewable resources are available to us, economic, technological, and environmental consideration currently limit their use as alternatives to fossil fuels• Fossil fuels are considers nonrenewable resources – natural resources that cannot be replaces – because they take millions of years to form naturally• Burning fossil fuels contribute to our carbon footprint and releases pollutants such as sulfur dioxide and nitrogen dioxide • Freshwater is considered a renewable resource• Lakes, reservoirs, and underground aquifers (underground layers of porous rock from which water can be drawn for use) is continually being replenished by the water cycle • As long as the rate of water withdrawal is less than the rate of replacement, the supply of freshwater remains relatively constant • Some countries experience water scarcity-geographic distribution of freshwater does not match the distribution of the world’s