Carbon Cycle Flashcards
What percentage of carbon is stored in the lithosphere?
99.9%
What percentage of carbon is stored in the hydrosphere?
0.04%
What percentage of carbon is stored in the biosphere?
0.004%
What percentage of carbon is stored in the cryosphere?
0.1%
What percentage of carbon is stored in the atmosphere?
0.001%
Processes driving change in the carbon cycle
Respiration
Photosynthesis
Diffusion
Sequestration
Decomposition
Weathering
Compaction
Combustion
Stages of succession in the lithosphere
bare rock colonised by pioneer species such as lichens
Dead organic material builds up and the exposed rock is further weathered
Mosses colonise rocks and soil forms when the rock is further weathered
Decomposition of organic matter leads to carbon in the soil
Grasses grow, roots cause biological weathering
Soil respiration improves quality
Larger plants grow due to more nutrients
Human causes of change in the carbon cycle
Hydrocarbon fuel extraction and burning
Farming practices
Deforestation
Land use changes
Natural causes of change in the carbon cycle
Volcanic activity
Wildfires
Today, the concentration of carbon in the atmosphere is the highest it’s been for how many years? What is it’s concentration?
Over 420 ppm (parts per million).
Outline the processof photosynthesis
• Transfers carbon stored in the atmosphere to biomass.
• Plants and phytoplankton use energy from the Sun to change CO2 and water into
glucose (carbohydrates) and oxygen. This enables plants to grow.
• Carbon is then passed through the food chain and released through respiration and
decomposition.
Outline the process of respiration
• Transfers carbon from living organisms to the atmosphere.
• Plants and animals break down glucose for energy, releasing CO2 and methane (which
contains carbon) in the process.
• This process is essentially the opposite of photosynthesis. Respiration takes O2 from
the atmosphere and replaces it with CO2. These processes are not in balance; the rate of photosynthesis is greater than the rate of respiration.
Name decomposers that help break organisms down, releasing carbon into the soil and atmosphere.
Bacteria, fungi and insects such as ants and beetles.
What makes decomposition essential for life on earth?
Decomposition ensures that carbon can be continually recycled into the soil and made available for life.
Process of combustion
• Transfers carbon stored in living, dead or decomposed biomass (including peaty soils) to the atmosphere by burning.
• Combustion occurs when any organic material is reacted (burned) in the presence of oxygen to give off CO2, water and energy.
• The organic material includes any vegetation or fossil fuel such as natural gas (methane), oil or coal.
• Wildfires cause carbon flow.
Weathering in carbon cycle
• Chemical weathering transfers carbon from the atmosphere to the hydrosphere and biosphere.
• Atmospheric carbon reacts with water vapour to form a mildly carbonic acid. When this acid rain falls onto rocks, a chemical reaction occurs which dissolves the rocks. The molecules resulting from this reaction may be washed into the sea. Here they react with CO2 dissolved in the water to form calcium carbonate, which is used by sea creatures, e.g. to make their shells.
Processes involved in natural sequestration of carbon
• Carbon from the atmosphere can be sequestered (captured and held) in sedimentary rocks or as fossil fuels. This effectively puts carbon into long-tern storage.
• The process begins with the transfer of carbon from the atmosphere to vegetation during photosynthesis and then to the soil during decomposition. Weathering also transfers carbon to the soil. Once in the soil carbon can transfer to the oceans via the water cycle where is can accumulate of the sea bed and become sedimentary rock through the process of burial and compaction.
• Rocks and fossil fuels form over millions of years when dead animals and plant material in the ocean falls to the floor and is compacted.
Identify the main carbon transfers found at the scale of a plant?
Respiration, photosynthesis and decomposition.
Identify the main transfers operating at a global scale.
Combustion, sequestration, ocean uptake and loss.
Ecological succession
A process in which the mix of plant species and habitat in an area over time. Gradually, plant communities replace one another.
Outline the main changes in the storage and cycling of carbon as succession moves from its first stage to the final stage of climatic climax.
At the beginning of a succession, e.g., a lithosere succession on bare rock, carbon is in the rock and the atmosphere. As the succession moves from the pioneer stage to the climatic climax carbon is transferred to biomass as the mass of vegetation increases due to photosynthesis and also to the soil due to decomposition and weathering.
Outline the main way in which wildfires change the carbon cycle (refer to the transfers and stores involved).
Wildfires rapidly transfer carbon from vegetation (and soil) to the atmosphere through combustion. Immediately, less photosynthesis occurs so less atmosphere is removed from the atmosphere. In the short-term atmospheric concentrations of carbon therefore increase.
Explain why fires may have a neutral effect on amount of atmospheric carbon in longer urn
In time vegetation will start to grow again and recolonise the area with vegetation (secondary succession). During this process photosynthesis will increase as plant communities develop, removing more carbon from the atmosphere, returning the system to equilibrium.
Identify a regional area that has been significantly affected by wildfires this century.
Indonesia, SE Asia (2013) or California, USA (2018).
Large wildfires can turn forests from being a carbon sink to being a carbon source.’ Explain this statement by referring to carbon cycle stores and transfers.
Natural forests, such as the Amazon, are large carbon sinks (as photosynthesis exceeds respiration each year increasing carbon stored in vegetation (biomass). However, if wildfires are extensive and intense (as is occurring more frequently as global temperatures increase), combustion returns large amounts of carbon to the atmosphere. This can have a lasting effect on the ecosystem, soils may be critically damaged and large- scale loss of trees may dampen rainfall to the extent that the forest never recovers. Through this positive feedback the area may become a carbon source.
Name a geological era when volcanos were more active than today, releasing large amounts of CO2 into the atmosphere.
Palaeozoic
Explain how the extraction and combustion of hydrocarbons impacts the carbon cycle.
Fossil fuels are hydrocarbons and form part of the huge stores of carbon locked away in the lithosphere. By mining and burning fossil fuel for energy and in industrial processes, this carbon is removed from long-term storage and enters the atmosphere, where is become part of the fast carbon cycle and increases the concentration of carbon in the atmosphere.
The burning of fossil fuels can be dated from the beginnings of the Industrial Revolution in 1750, but the rate of burning has increased since 1950. Give reasons why.
This is due to the rapid industrialisation of developing nations (such as India and China) as well as the continued demand from the world’s industrialised nations such as the USA.
According to the Intergovernmental Panel on Climate Change (IPCC), what percentage of human related global CO2 emissions come from burning fossil fuels?
90%
Outline impact of cement manufacture on carbon cycle
Cement manufacture involves the heating of calcium carbonates (e.g. limestone). This produces CO2 and lime. CO2 is also produced by burning fossil fuels to provide the heat for the cement manufacture process. It is estimated that the cement industry produces 5% of global anthropomorphic CO2 emissions.
Agriculture is responsible to significant carbon emissions. Outline three farming activities responsible for emissions.
• Livestock release CO2 and methane when they respire and digest food. This is the largest source of CO2 within agriculture.
• Ploughing can release carbon stored in the soil. When soil is turned over, air mixes in and soil microbial activity increases. This results in soil organic matter being broken down more rapidly, and carbon is lost from the soil and transferred into the atmosphere as CO2.
• Growing rice in rice paddies releases a lot of methane.
Rice paddies + emissions
accounts for over 40% of agriculture-related greenhouse gas outputs occur in Asia.
Give two reasons why agricultural activities are having an increasing impact on the carbon cycle.
• As the world’s population has risen, so has food production. As a result, carbon emissions from farming practices have increased.
• Mechanisation of farming has also increased CO2 emissions as more tractors and other farm vehicles are used across the globe.
Give three reasons why deforestation may occur.
Forests may be cleared for agriculture, logging, or to make way for development and urban sprawl.
Outline the impact of deforestation on the carbon cycle (identify changes in stores and the transfers involved)
Clearance reduces the size of the carbon store and, if the cleared forest is burned, there is a rapid flow of carbon from the biosphere to the atmosphere.
In a natural system, when a tree dies it decomposes very slowly and releases carbon over a long period of time.
During that time, new vegetation starts to grow that quickly compensates for the carbon being released by the dead tree (the system is carbon neutral).
However, when deforestation by burning occurs, carbon is immediately released into the atmosphere. If the land is then used for farming e.g. cattle ranching, the future absorption of carbon will be reduced. The system has now become a carbon source rather than a sink.
This is extremely significant in terms of the carbon cycle both globally and regionally, as forest ecosystems are limited to certain regions of the world.
Identify global locations experiencing significant deforestation.
Tropical regions, for example, Indonesia and the Amazon Basin.
Outline the ways in which the processes of urbanisation drives change in the carbon cycle.
• Vegetation is removed, or covered up, to make way for buildings – this reduces carbon storage in the biosphere.
Concrete production releases lots of CO2 and concrete is used when urban areas expand.
What proportion of human related CO2 emissions come from urban areas and what are the main sources?
• 97% of all anthropomorphic CO2 emissions come from urban areas. Over half of the world’s population now lives in urban areas; a proportion that is set to grow over the coming decades.
• The major sources of these emissions are transport, energy generation, the development of industry, land use conversion from rural to urban and cement production for the building sector.
Define‘carbonbudget’.
The difference between the inputs of carbon into a subsystem and outputs of carbon from it. The focus is on carbon emissions into the atmosphere compared to the amount of carbon removed each year.
List the carbon transfers that cause an input of carbon into the atmosphere (natural and human).
Volcanic eruptions, burning fossil fuels, respiration and ocean loss.
List the carbon transfers that cause an output of carbon from the atmosphere (natural and human).
Photosynthesis, sequestration, decomposition, chemical weathering and ocean uptake.
Naturalsystems,suchasbiomass(includingvegetation)andtheoceanshaveoperated as carbon sinks. What does this mean and what transfers are involved?
A carbon sink ‘banks’ carbon. Each year inputs of carbon are greater than outputs. Forests (through photosynthesis) and the oceans (through dissolution or uptake) have been major carbon sinks.
In recent decades human processes have turned carbon sinks into carbon sources. Which human activities are driving this change in the carbon cycle? Which transfers/processes are being affected?
Large scale and rapid release of CO
from a combination of combustion of fossil fuels and
changes in land use patterns are occurring at rates beyond the capacity of natural systems
to compensate. This results in rapid increases in CO
concentrations the atmosphere.
Changes in the carbon budget (essentially the increase in inputs of carbon to the atmosphere and the reduction in carbon stored on land) are having an impact on the land, oceans, atmosphere and global climate. Identify impacts on land
More CO2 is available to plants and longer growing seasons, result in more
photosynthesis and plant growth. Growth limits will depend on water and nutrient
availability. (Negative feedback)
Increased temperatures have led to warming in Tundra regions and the melting of
permafrost, releasing carbon stored into the soil into the atmosphere as CO2 and
methane. (Positive feedback)
Changes in the carbon budget (essentially the increase in inputs of carbon to the atmosphere and the reduction in carbon stored on land) are having an impact on the land, oceans, atmosphere and global climate. Identify impact on oceans
Warmer water is less able to absorb CO2, so as temperatures increase the amount of
CO2 that can potentially be dissolved in the sea decreases. (Positive feedback)
Warmer ocean temperatures are adversely affecting other marine organisms. For
example, phytoplankton may not survive at higher temperatures, so numbers may
decline. This means less will be used for photosynthesis, leaving more CO2 in the
atmosphere. (Positive feedback)
Changes in the carbon budget (essentially the increase in inputs of carbon to the atmosphere and the reduction in carbon stored on land) are having an impact on the land, oceans, atmosphere and global climate. Identify impact on atmosphere
The increasing concentration of greenhouses gases in the atmosphere increases
temperatures. Greenhouse gas emissions have increased significantly in recent
decades due to human activities such as deforestation and fossil fuel combustion.
This has led to an enhanced greenhouse effect.
Global warming will affect other aspects of the climate, including global
atmospheric winds, rainfall distribution and intensity and the frequency of storms.
What is the IPCC and what is its primary aim?
The Intergovernmental Panel on Climate Change (IPCC) is an international organisation set up by the UN to share knowledge about climate change. The IPCC states that countries need to reduce the amount of CO2 emitted by human activities, to prevent large temperature rises.
Outline how carbon capture and storage (CCS) could help mitigate climate change.
CO2 emitted when burning fossil fuels is captured and liquified then transported to be stored, often deep underground
What is a disadvantage of CCS?
It doesn’t discourage fossil fuel burning or the extraction of fossil fuels and is also relatively expensive.
Name an international agreement to reduce emissions.
Kyoto Protocol (1997) or the Paris Agreement (2015)
