Climate Change and Land Cover

• Students will investigate the links between the change in land cover and changes in the global climate using fieldwork and secondary sources.
• The study will cover the spatial distribution of rainfall and temperature, and the crucial components of natural systems, and how they influence climate

Key Elements of Natural Systems:

• Heat budget, including the greenhouse effect
• Hydrological cycle
• Carbon cycle
• Atmospheric circulation

Natural Systems

• Natural systems examine the interaction between different elements in the natural environment.

Climate Change Viewpoints

• Sceptics believe climate change is due to natural cycles, not human activity, and is uncontrollable.
• Middle viewpoints: Both natural processes and human-induced greenhouse gas emissions contribute, making some effects manageable.
• Believers think human activities cause climate change by releasing greenhouse gases.

Climate Change Defined

• Climate change is a long term change in the statistical distribution of weather patterns over periods of time that range from decades to millions of years.
• Change happens in average weather or the distribution of weather events, like more or fewer extreme events.
• Climate change may be specific to a region or across the whole Earth, causing global cooling or warming.
• Recent human activities are significant causes of current climate change or more recently referred to global warming.

Weather vs. Climate

• Weather is the short-term changes in the atmosphere, from minutes to months and is a 'snap-shot'.
• Climate describes the long-term pattern of weather in an area with climatologists look at averages of precipitation, temperature and humidity over decades to centuries.
• Climate variability differs between average expected conditions and actual seasonal conditions from year to year.

Factors Affecting Climate

• Natural factors affecting climate can be remembered using LAPPDOG.
• Latitude: Temperatures decrease with increasing latitude toward the poles with sunlight is direct and concentrated at the equator but dispersed at the poles due to the angle of incidence.

Rainfall and Temperature Patterns

• Spatial distribution is how something (phenomena) is arranged on the earth's surface.
• Patterns arise through the distribution of the phenomena, including clustered/nucleated, peripheral, grid, linear, radial, and dispersed/scattered patterns.
• Studying changes in spatial distribution over time reveals the impacts of climate change.

Global Rainfall Distribution

• High rainfall at low latitudes near the equator because of high levels of rising moist air, exceeding 2500ml (e.g., Cherrapunji, India).
• Mid-latitude regions (23.5-55 degrees N/S) experience moderate to high rainfall from cold fronts within subpolar or mid-latitude low-pressure systems (e.g., NZ at 40 degrees S experiences up to 1600mm).

Earth's Natural Systems

• Natural systems are responsible for long-term climatic patterns and complex biogeochemical cycles that influence Earth's long-term climate.
• Disruptions to these systems, mainly by human activity, cause climatic variations.
• Natural systems include the heat budget, natural greenhouse effect, hydrological cycle, atmospheric circulation, and carbon cycle.
• Solar energy drives each system, with each square meter of Earth absorbing 240 watts of insolation.
• The spherical shape of the Earth distributes insolation unevenly, with equatorial regions receiving more than polar regions.
• The Earth's axis is tilted at 23.5 degrees, causing varying rates of heating and cooling across different areas, which result in clear seasonal climatic patterns.

Heat Budget

• The global heat budget balances incoming short-wave solar radiation (insolation) and outgoing long-wave (terrestrial radiation).
• The amount of insolation equals the amount of energy lost to space which keeps the planet's temperature constant.
• Insolation is affected by reflection back into space, absorption by the atmosphere, and absorption by Earth's surface.

Earth's Energy Balance

• The sun provides 100% of the energy to the Earth, but not all of it reaches the surface.
• 30% of solar energy is reflected back into space: 6% by the atmosphere, 20% by clouds, and 4% by the Earth's surface (albedo effect).
• 70% of solar energy is absorbed: 16% by the atmosphere, 3% by clouds, and 51% by land and oceans.
• Once absorbed, land and oceans release energy through conduction (7%) and latent heat (23%).
• 65% of absorbed energy is radiated back into space by clouds and the atmosphere, 6% directly from the Earth's surface (atmospheric window), and 15% is absorbed by the atmosphere (greenhouse effect).
• Insolation is high energy and easily passes through the atmosphere, while terrestrial long-wave radiation cannot.

Natural Greenhouse Effect

• The atmosphere naturally traps outgoing heat (longwave radiation), sustaining life.
• Greenhouse gases (CO2, methane, water vapor) absorb and re-radiate heat, with 15% of radiation absorbed before being released into space.
• The Earth would be 33°C cooler without greenhouse gases.
• Increased greenhouse gases have unbalanced the heat budget, leading to more heat being absorbed.

Greenhouse Effect Revision:

• The greenhouse effect is a natural mechanism that keeps the planet warm and livable.
• Sunlight is absorbed Earth's surface, visible light (short wave radiation) transforms into infrared (long wave radiation), which is then radiated towards the atmosphere.
• Greenhouse gases (carbon dioxide, water vapour and methane) in the atmosphere entrap heat and emit it back, which reduces heat loss to sustain a warmer climate.
• In absence of greenhouse gases, Earth’s atmosphere would average -30 to -35°C, which would make life as we know it, impossible.
• The enhanced greenhouse effect happens due human activities, contributing additional heat.
• This process happens largely because of increased cabon dioxice since the Idustrial revolution where C02 was about 280 ppm but rose to over 400 ppm in 2016, and methane similarly increased from 800 ppb to around 1790 ppb in 2008.
• Rising concentrations of C02 and methane signify a change the atmosphere's capcity to absorb and emit heat with reduced C02 removal and diret production from burning fossil fuel.
• These shifts have led carbon dioxide (CO2), which, has risen by 48% and increased global surface temperatures by 1.1 degrees Celsius since industrial revoultion.

Hydrological Cycle Definition

• The continuous movement of water as a liquid, gas, and solid throughout Earth.

Hydrological Cycle:

• The cycle constantly recycles fresh water.
• Only 3% of Earth's water is fresh of which glaciers and ice caps hold 69% and groundwater 30%.
• Solar energy drives evaporation, where water turns from liquid to gas.
• Most evaporation occurs over oceans, covering 70% of Earth's surface, where salt and minerals are left behind.
• Condensation happens when water turns from gas to liquid, releasing latent heat into the atmosphere
• Droplets merge with microscopic particles to grow and create clouds which causes precipitation.
• Precipitation occurs when rain, snow, sleet or hail falls from the sky to the earth.
• Infiltration sees water soaking into the ground.
• Groundwater is water that is collected underground in aquifers and eventually seeps into creeks, rivers, laker or other water bodies.
• Run-off occurs when water does not soak into the ground and rather flows across the land.
• Plants use photosynthesis involving water that is evaporated from pores by transpiration or essentially plant sweating where 10% of the atmospheric water vapour comes from.
• Evapotranspiration comes from evaporation from water sources, the soil and transpiration from plants.
• The hydrological cycle influences climate, regulating weather events like rainfall, humidity, cloud cover, and temperature.

Carbon Cycle Definition:

• The movement of carbon compounds between land, oceans, atmosphere, and living organisms.
• Carbon is a building block for life, extracted by plants and animals and is a gas in the atmosphere.
• Carbon is found in rocks, dead organic material in soils, and fossil fuels.

Carbon Cycle Key Elements:

• Processes that remove and store carbon dioxide from the atmosphere.
• Processes that release carbon dioxide back into the atmosphere.
• Most carbon is stored in rocks, the ocean, the atmosphere, plants, soil, and fossil fuels.
• Carbon Dioxide, accounting for 0.04% of the atmosphere, plays a crucial role in the planet's energy balance by helping regulate regulate the earth's over all temperature.
• Carbon is constantly exchanged with the oceans and is removed from the atmosphere by photosynthesis, erosion, and sedimentation. This creates cold, sinking water and transfers it to the bottom of the ocean, combining with sand or shells to form sedimentary rocks to store carbon for millions of years which rises closer too the surface when warm which then causes evaporation.

Carbon Exchange

• Plants and the atmosphere exchange carbon where plants remove carbon for phtotsynrhesis provide energy to its cells.
• Oxidation of carbon provides life through respiration, returning carbon back into the atmosphere.
• There are two carbon cycles: 1) the act within a single lifespan and 2) that operate over a 100 to 200-million-year cycle to prevent prevent the Earth from entering the atmosphere or lithosphere.

Carbon Cycle Disruptions & Statistics:

• Direct burning of fossil fuels releases stored carbon to creates imbalances warmer temperartures.
• Reductions in carbon include warming of oceans clearing of forests which results in releases which increases the amount of greenhouse gas in the atmosphere to trap energy. Since the industrial revolution, carbon in the atmosphere has risen by 48%, accompanied by 1.1 degrees Celsius because humans activities have increased carbon amount.

Atmospheric Circulation Definition:

• Large-scale air movement distributing thermal energy across Earth with processes known as convection.

Atmospheric Circulation Mechanics:

• Hot air rises because heated air is less dense, causing it to rise from the Intense heat from the sun's heat along the equator that creates a low-pressure zone, leading to cloud formation and rainfall.
• Cold air sinks because colder air is denser, causing it to sink around 30° and 90° latitudes and is dry.

Atmospheric Circulation Cells

• The Hadley cell: Forms in regions receiving most direct sunlight, its warm air rises to become less dense as the warm air rises near equator and creates thunderstorms which produces air pressure differences between the equator that gives power to trade withns.
• Polar Cell is is similar thermally driven but with cool dry air (yet, is still warm enough to drive convection to create polar easterlies.
• Ferrel Cell: Located between Hadley and polar cells, it typically resides near latitude in both hemispheres and air rises here which produces prevailing westerly winds commonly in Southwest WA is produces by Corollis Effect.
• The Intertropical Convergence Zone (ITCZ) is a zone of low pressure circling near the equator with thunderstorms and heavy rainfall.
• Trade winds are east toward the equator in both hemispheres, blowing from northeast and southern hemispheres respectively.
• The Coriolis effect sees the deflection of moving air and water because of rotation in the Northern Hemisphere.
• Westerlies see prevailing winds that blow from west to east between 30° and 60° latitude.

How to Characterzie Atmospheric Circulation

• Rainforests form in equator due to rising air or low pressure resulting in condensation.
• Deserts form 30° due to sinking air or high pressure that causes temperatures that is dry.
• Storms/ temperate regions at 60 degrees due to rising air.
• Cold and dry poles at 90 degrees dues too sinking air
• Low pressure systems = Areas in low pressure that are from equatorial equator/polar regions that are typically associated that the are typically associated with unstable inclement weather:
• High pressure systems = Areas in low and polar parts systems and high parts of pole are stable and may result in blue skies.
• This is also a result of a tilt in the sun and will shift over the year that may cause or prevent weather like hot or dry seasons