Global Systems The Biosphere The Biosphere Earths life
Global Systems The Biosphere
The Biosphere • Earth’s life support system • Broken into four components: - Atmosphere - Lithosphere - Hydrosphere - Biota • Carbon, nitrogen and phosphorus move between these spheres in cycles
Atmosphere • Gases surrounding the Earth, by gravitational pull. • Split into layers. The two we are most interested in are the troposphere and stratosphere. • Troposphere: - Lowest level. 6 -20 km above surface depending on location. • Stratosphere: - Directly above Troposphere - Extends to roughly 50 km above the surface - Contains ozone layer, which absorbs UV radiation - Does not absorb IR or visible light
Human Impact on Atmosphere • Chloroflurocarbons (CFCs) have been widely used in aerosols, refrigeration, and as industrial solvents • Chlorine reacts readily with ozone in stratosphere, depleting the ozone layer, and potentially exposing the surface to UV radiation • CFCs largely phased out, replaced by hydrochloroflurocarbons (HCFCs), then hydroflurocarbons (HFCs)
Lithosphere • Includes the Earth’s crust, including sedimentary, igneous, and metamorphic rocks, as well as the soil • We divide the surface of the planet into different regions that we call biomes • Biomes are determined by the dominant type of vegetation, which is in turn determined by temperature, rainfall, latitude, etc.
Human Effect on Lithosphere • Negative effects on the lithosphere can be caused by: - Overstocking - Soil exhaustion - Salinity - Pesticides - Unstable landfill - Chemical emissions • These activities can lead to destruction of habitat and resources required by organisms
Hydrosphere • Water, regardless of phase.
Human Effect on Hydrosphere • Toxic materials move into water systems, and are absorbed by organisms in the ecosystem • As we move up the food chain, toxins are biologically magnified, and become more concentrated • Can be dumped deliberately, or result from surface runoff
Biota • Biota includes all living things. From large multicellular animals, all the way down to single-cell organisms (depending on who you ask) • Complexity of system increases with size
Carbon Cycle • All life on Earth is built around carbon • Forms huge range of organic and inorganic compounds • Exists in hydrosphere as dissolved CO 2, in lithosphere as fossil fuels and some rocks, in atmosphere as CO 2 and methane, in biota as a vast number of organic molecules.
Carbon Cycle
Human Effect on Carbon Cycle • Burning fossil fuels releases CO 2 into atmosphere • Deforestation and human-driven vegetation changes reduces CO 2 removed from atmosphere • This leads to enhanced greenhouse effect and global warming
Nitrogen Cycle
Phosphorus Cycle
Human Effect on Nitrogen/Phosphorus Cycles • Fertilisers are typically rich in nitrogen and phosphorus, and are used to improve growth of crops • Large scale usage has led to large amounts of N and P moving into water systems, which can cause eutrophication • Eutrophication refers to the explosive growth of algae and plant life • Nitrogen oxide reacts with water vapour in the atmosphere to produce nitric acid, which leaves the atmosphere as acid rain.
Questions • 7. 1 Q. 3, 16, 17, 18, 19, 20, 21, 23
Climate • Weather is the day-to-day atmospheric conditions such as temperature, wind and humidity • Climate refers to the statistics of these conditions over longer periods of time • Climate is influenced by: - The amount of sunlight incident on the surface - The abilities of land water to absorb/emit radiation - Tilt of the Earth’s axis - Land features
Ocean Currents • Result from temperature difference between equator and poles • Warm water at the equator cools and sinks as it approaches the polar regions • Cool water at the poles warms and rises as it moves towards the equator • This has a major influence on the climate of coastal regions
Wind • Caused by convection currents • Cold air sinks at poles, warm air rises near equator, creating a cycle. • Also subject to a number of other complicating factors, which makes direction difficult to determine • The direction influences air temperature.
Action of Bacteria • Nitrogen fixing is the process by which N 2 in atmosphere is split and converted to ammonia (NH 4). This also occurs as a result of lightning strikes. • Nitrification converts ammonia to nitrite (NO 2 -), and then converts that nitrite to nitrate (NO 3 -). • Denitrification is the reverse. Through a series of steps, converts nitrate back to nitrogen gas (N 2).
Greenhouse Effect Learning Intention: • To understand how the presence of some gases give rise to the greenhouse effect Success Criteria: Students can… • Name major greenhouse gases, and identify their sources • Explain how these gases trap heat • Describe the difference between the greenhouse effect and the enhanced greenhouse effect
Greenhouse Gases • A greenhouse gas is a gas capable of absorbing, then re-emitting infra-red light from the Earth • All objects above -273°C emit radiation, and the surface of the Earth emits in the infra-red range (as do we!) • Major greenhouse gases are: Carbon dioxide (CO 2), methane (CH 4), nitrous oxide (N 2 O), and a variety of CFCs
Greenhouse Gases
Greenhouse Effect • The greenhouse effect is the process in which heat emissions from the Earth are prevented from escaping by gases in the atmosphere • This results in a relatively stable surface temperature, allowing life to flourish
Enhanced Greenhouse Effect • Increased burning of fossil fuels and certain aspects of agriculture has increased the amount of greenhouse gases in the atmosphere. • This has resulted in the atmosphere heating up, rather than maintaining a stable temperature • We call this the enhanced greenhouse effect, and results in global warming and climate change.
Questions • 7. 3: 1, 2, 4, 9, 10
Global Warming • The increase of Earth’s average surface temperature due to the enhanced greenhouse effect • Climate change is slightly different, and refers to the long term change in the climate of a region, rather than just an increase in temperature.
Global Warming - Evidence of global warming includes: • Increase in global temperature measurements • Sea level rise • Warming oceans • Shrinking ice sheets • Declining sea ice • Retreating glaciers • More frequent extreme weather events • Ocean acidification • Decreased snow cover
Global Warming - Evidence
Global Warming - Evidence
Global Warming - Evidence
Global Warming - Consequences • Melting of permafrost • Rising sea levels • Disruption of ocean and wind patterns • Spread of disease • Further ocean acidification
Modelling • The process by which we represent complex systems in a way that is easier to understand • Additionally, can be used to represent systems we cannot recreate in order to test • Allows us to make predictions about the future, if we have information about current conditions
Where to now? • Many world leaders signed a document called the Kyoto protocol in 1997. • This was an agreement between different countries to reduce carbon dioxide emissions to specific targets. • Not legally binding, but signified the beginning of global cooperation on climate change.
Global temperatures naturally increase and decrease in cycles. We should not be worried about increasing temperatures
Australia should take action to address climate change
Australia should take action to address climate change, unless it places us at an economic disadvantage
Australia should not work to reduce carbon dioxide emissions until countries with higher emissions are doing the same
Australia should develop nuclear fission reactors to reduce carbon dioxide emissions
Malcolm Roberts understands what he’s talking about
What you need to know • • Biosphere and its components Water, carbon, nitrogen, phosphorus cycles Ocean currents and wind Ozone layer and CFCs Greenhouse/enhanced greenhouse effect Global warming – Evidence, consequences, and solutions Kyoto protocol
Exit ticket • Write down one thing you have learned during this topic • Write down something you would like to learn about in our topic on space. This could be in the form of a question, or just a particular object or process.
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