8.1 Energy Transfer in the Climate System Open system: The human body receives food, water, and nutrients and releases waste products and heat Closed system: The atmosphere allows energy to enter but restricts other materials from entering or exiting.
Feedback Loops in the Earth’s Closed System Earth being a closed system, it must circulate all of its matter within its boundary. – The interactions between the earth’s materials create a feedback loop (i.e. A impacts B which impacts C impacting A again)
Positive Feedback Loops A positive feedback loop is a feedback system where each of the items on the loops will increases its effects every cycle Increase in global warming Increase in the rate of melting ice Decrease in albedo
Negative Feedback Loops A negative feedback loop is a feedback system where each cycle brings the system closer towards equilibrium. – Each cycle will decrease the effects of the items in the loop Decrease in attentiveness Decreased sleep time Increased test perromance Increase in time studying Decrease in grades
Energy and Heat on Earth The earth has 3 main types of energy transfer that help to heat the earth: 1.Radiation: Electromagnetic radiation in the form of waves emitted by a heat source. - Radiation can be either absorbed, reflected or refracted. 2.Conduction: The transfer of energy between two objects 3.Convection: The transfer of energy due to moving objects (e.g. liquid, gas [not solid])
Conduction, Convection, and Radiation in the Earth’s Atmosphere On Board (Figure 8.4)
Earth’s Energy Budget Energy is either: absorbed by the clouds, atmosphere or land (70%) reflected by the clouds, atmosphere, or land (30%) The measure of the clouds and land structures (ice, snow) ability to reflect solar radiation is known as its albedo.
Global Warming and Albedo Dark coloured earth structures mainly absorb radiation = low albedo Light coloured structures reflect radiation = high albedo – The more ice that melts the greater amount of radiation will be emitted resulting in increased temperatures. – However, increased temperatures cause more evaporation, which increases cloud cover, which increases albedo
Energy Transfer in the Oceans Ocean circulation occurs due to the thermohaline circulation (affected by temperature and salt) – The current is referred to as “the great ocean conveyer belt” – Water at the poles is colder/saltier = more dense = sinking – As cold water sinks, warm water rises to the surface creating a warm surface flow. – In this manner energy is transferred throughout the oceans
Global Warming and Thermohaline Circulation Global warming causes an increase the overall temperature – Leads to melted ice at the poles = less saline water = less dense water = does not sink – Leads to increased evaporation at the tropics = more saline water = more dense = sinking These effects may reverse the thermohaline circulation or stop it entirely resulting in uneven distribution of energy in the ocean
8.2. Greenhouse Gases and Human Activity Carbon dioxide in the Earth’s atmosphere is currently approximately 370 ppm What does this mean? It means that of every one million parts in the atmosphere, 370 are carbon dioxide
Atmosphere Composition 90% of the atmosphere is made up of N 2 (nitrogen) and O 2 (oxygen) – These are not greenhouse gases Greenhouse gases are water vapour, carbon dioxide, methane, nitrous oxide, ozone. Source: Processes that add greenhouse gases Sinks: Processes that remove greenhouse gases
Sources and Sinks The source of carbon dioxide in the atmosphere is primarily due to animal respiration. – Human’s burn fossils which also contributes to carbon dioxide Plants/phytoplankton remove carbon dioxide making them carbon sinks
Methane Common to bogs and swamps (e.g. wetlands) Cattle contribute a large portion of the methane production through gas release. Waste products (manure) also contributes to methane production.
Nitrogen Oxide From damp tropical soils and the oceans Anthropogenic sources: Chemical fertilizers, manure, vehicle exhausts
Ozone (O 3 ) Occurs naturally in the atmosphere Blocks harmful UV radiation
Ozone Depletion Ozone has been depleting for the last 30 years Depleted ozone allows for harmful UV radiation to pass through the atmosphere – Increases cancers of the skin Caused by chlorine containing gases
Ground Level Ozone Ozone can also be found at ground level due in the form of smog – Smog is composed of sunlight and vehicle exhaust chemicals – Smog causes damage to the lungs and heart
Halocarbons Are carbons bound by halogens Most common halocarbon found in the atmosphere is chlorofluorocarbons (CFC’s) – Are gases that have depleted the ozone over Antarctica – Found in solvents, cleaners, old refrigerators
Reducing Greenhouse Gases Conserve electricity: – Energy efficient lights, new appliances, conserve. Improve home heating – Update furnace, retrofit (windows and seals) Reduce, re-use, and recycle – Be frugal in using products, reuse products, and dispose in the correct bins.
8.3 Jigsaw Activity In this activity groups of four will be made Each student within the group will be given a number (i.e. 1, 2, 3, 4) Each student must read these pages and summarize the key ideas to the group along with any figures – Student 1: Read pages 333-334 ( up to “The Global Carbon Budget”) – Student 2: Read page 334 (“The Global Carbon Budget”) and page 335 (The carbon cycle) – Student 3: Read page 336 (“How human act…) and page 337 – Student 4: Read pages 338-339.