1. Water and carbon cycles as natural systems Flashcards
what is a system
any set of interrelated components which are connected together to for a working unit or unified whole
Systems themselves can be quite complex, but they aim to show a generalisationofreality
differentiate between open, closed and isolated systems
Closed systems - these have transfers of energy into and beyond the system boundary but not a transfer of matter
Open systems - these are where matter and energy can be transferred from the system across the boundary into the surrounding environment. Most ecosystems are examples of open systems
Isolated systems - these systems have no interactions with anything outside the system boundary. There is no input or output of energy or matte. Usually confined to laboratory experiments
what is dynamic equilibrium
Where there is a balance between inputs and outputs the system is balanced
differentiate positive and negative feedbacks
Positive Feedback – where the effects of an action (e.g. an increase in carbon dioxide) are amplified or multiplied by subsequent knock-on or secondary effects and the system reaches a new state that is often irreversible
Negative Feedback – where the effects of an action are nullified by its subsequent knock on effects and the system can return back to its original state
describe water vapour, albedo and permafrost methane as positive feedback loops
Water vapour -
As air gets warmer, its capacity to hold moisture increases. + climate change -> + atmosphere warming = holding more water vapour.
Water vapour is a potent greenhouse gas it helps the Earth hold on to more energy from the sun, warming the climate further
Albedo -
Albedo is the amount of light reflected by a surface
A surface with a high albedo (snow or sand) will reflect more sunlight. The lower the albedo, the more energy and heat is absorbed. Global warming is causing ice and snow to melt, revealing the land or ocean underneath.
As the ice melts, more of the sun’s energy is absorbed and so the planet gets warmer still - which in turn melts even more snow and ice.
Permafrost methane -
At higher latitudes, organic rich soils are frozen over by permafrost, and the greenhouse gases are locked away. When the soil thaws due to rising temperatures, these gases are released as CO2or methane. This causes further heating and as a result more permafrost is melted
describe Land and carbon cycle and clouds as negative feedback loops
Land and carbon cycle (currently negative feedback) -
For every tonne of carbon dioxide (CO2) released into the atmosphere, within a year about half of that will be absorbed by the ocean and land, e.g. through trees and plants.
Global warming could affect the carbon cycle in two ways:
Oceans - the ocean is a carbon sink, however as the ocean absorbs CO2 it becomes more acidic, reducing the amount of CO2 it can further absorb.
As the temperature of the ocean increases this reduces its capacity to absorb CO2.
Land - negative feedbacks, due to temperature increase the areas in which trees can grow will extend north to higher latitudes. New trees will absorb CO2, taking it out of the atmosphere.
Positive feedbacks around the tropical zones. As temperatures increase, soils, plants and trees in these areas will become more heat stressed - potentially releasing huge amounts of carbon they store
Clouds (positive and negative feedback) -
higher co2 makes earth’s skies hotter. The heat drives stronger turbulence inside the clouds, breaking up the cloud. This means that less solar radiation is blocked.
However some high clouds reflect heat away from the earth
define biosphere, hydrosphere and lithosphere
biosphere - the worldwide sum of all ecosystems
hydrosphere - a discontinuous layer of water at or near the earth’s surface, includes all liquid and frozen surface waters, groundwater held in soil and rock and atmospheric water
lithosphere - the solid, outer part of Earth. The lithosphere includes the brittle upper portion of the mantle and the crust, the outermost layers of Earth’s structure
what is a macropore
when spaces between soils and rocks are larger than 1mm
formed when plant roots create channels within the soil
how do macropores increase flood risk
connected macropores mean that water can flow through quicker
resulting in flashier hydrographs
how do macropores decrease flood risk
greater infiltration can take place because of the increased permeability
how do macropores affect water pollution
natural soil pipes allow for easy transportation of water meaning pollution on a hillslope 100 of meters away could be transported directly towards the stream
how do macropores affect land instability
when pipes become large their roofs may collapse creating slope instability
what is a tipping point
the critical point in a situation, process, or system beyond which a significant and often unstoppable effect or change takes place
