Water + Carbon Cycle Flashcards
What is a system?
A set of interrelated components working together towards some kind of process
What is a open system?
Energy and matter move through the system. E.g. Drainage basin
What is a closed system?
Energy can be moved through the system but matter cannot, E.g. Global water cycle/storage
What is an isolated system?
Almost non-existent. No exchange of energyor matter with another system. Only true isolated system is the whole universe.
What is negative feedback?
Where the effects of an action are nullified (reduced or stopped) by its subsequent knock-on effects.
What is positive feedback?
Where the effects of on action are amplified or multiplied by subsequent knock-on effects.
What is dynamic equilibrium?
The inputs and outputs are equal and the system is in balance
An example of positive feedback?
Global temps increase = ice caps melt = increased amount of ocean surface = albedo effect, dark surfaces absorb heat = global temps increase +etc…
An example of negative feedback?
Hot, dry weather = drought conditions = heat = evapo transpiration = clouds form = rain (doesn’t return system to equilibrium so weaker than positive feedbach)
An example of positive feedback?
Global temps rise which warms the oceans so increased oceanic temps’ warm water is less able to dissolve gas so dissolved CO2 released by warmer oceans which releases CO2 back into the atmosphere therefore there is more CO2 in the atmosphere which act as a greenhouse gas so global temps rise + etc…
An example of negative feedback?
Initial change = climate cooling = increased snow+ ice; higher reflectivity = less solar radiation absorbed at surface = greater cooling
What is atmospheric water?
Water found in the atmosphere; mainly water vapour with some liquid water (cloud and rain droplets) and ice crystals
What is cryospheric water?
The water is locked up on the Earth’s surface as ice
What is oceanic water?
The water contained in the Earth’s areas and seas but not including such inland seas as the caspian sea
What is terrestrial water?
This consits of groundwater, soil, moisture, lakes, wetlands and rivers
What is the global distribution of water?
96.5% = oceans, 0.9%. = other saline water, 2.5% = freshwater. Of the freshwater, 68.7% = glaciers + ice caps, 30.1% = groundwater, 1.2% = surface/other fresh water. Of the surface/other freshwater, 69% = ground ice + permafrost, 20.9% = lakes, 3.8% = soil moisture, 2.6%= swamps + mashes, 0.49% = rivers, 0.26% = living things, 3% = atmosphere
What is an ice sheet?
A Mass of glacial Land ice extending more then 50,000 square kilometers.
What are the two ice sheets on Earth today?
Antarctic Ice sheet (extends almost 14 million square km and contains 30 million cubic km of ice) Greenland ice sheet (extends about 1.7 million square km)
How do ice sheets form?
-
Form in areas where snow that falls in winter doesn’t melt entirely over the summer. Over thousands of years, the layers of snow pile up into thick masses of ice, growing thicker and denser as the weight of new snow and ice layers compresses the older layers
How do ice sheets move + remain stable?
Constantly in motion, slowly flowing downhill under their own weight. Near the coast, most of the ice moves through relatively fast- moving outlets called ice streams, glaciers and ice shelves - as long as an ice sheet accumulates the same mass of snow as it loses to the sea, it remains stable.
Why are ice sheets important?
They contain enormous quantities of frozen water if the Greenland ice sheet melted sea level would rise about 6 metres, if the Antarctic ice sheet melted sea level would rise about 60 metres Ice sheets also influence weather and climate and the layers of ice contain a unique record of the Earth’s climate history.
How has climate change affected ice Sheets?
The mass of the Greenland ice sheet has begun to decline. From 1979 to 2006,
Summer melt on the ice sheet increased by 30%. The Antarctic peninsula has warmed 2.5°C since 1950 also a large area of the West Antarctic ice sheet is also losing mass
How can ice sheets tell us about Earths climate history?
Can extract ice cores from ice Sheets and ice caps • Ice sheets are made up of layers of snow and ice, those layers contain trapped gases, dust, and water molecules that can be used to study past climates
What is the biosphere?
Contains all the planet’s living things
What is the lithosphere?
Contains all Land in the earth’s crust and core
What is the hydrosphere?
Contains all the solid, liquid and gaseous water
What is the atmosphere?
Contains all the air in the Earth’s system
What are the links between the biosphere and atmosphere?
Plants absorb CO2 for photosynthesis.- animals release CO2 into atmosphere (respiration)
What are the links between the biosphere and lithosphere?
Plants absorb minerals in soil
What are the links between the lithosphere and hydrosphere?
Rain falls from clouds to form streams and rivers
What are the links between the atmosphere and hydrosphere?
- rain falls from clouds- precipitation - evaporation
What are the links between the atmosphere and lithosphere?
Volcanic eruptions and fracking
What are the links between the biosphere and hydrosphere!
Plants absorb water for growth
Definition of sublimation?
The conversion between the solid and the gaseous phases of matter, with no intermediate liquid stage
Definition of deposition?
Change of state from a gas to a solid
What is surface tension of water?
Caused by a strong hydrogen bond
What is latent heat?
As water molecules become heated by the sun they become agitated and they begin to try to break the bonds between them. However there is not enough heat from the sun ray to do this so water molecules absorb energy from their surroundings to give them the final energy that they need to break the bonds between them. Energy is known as latent heat. As the latent heat is taken from the surroundings it cools the surroundings down.
Why do clouds form?
Clouds form when warm air cools. This makes water vapour condense into water droplets which gather as clouds. When droplets get big enough they fall as precipitation. Water droplets are too small so there are also condensation nuclei (dust or soot) which give the water a surface to condense on.
Why does warm air cool down?
- Other air masses - warm air is less dense than cool - when they meet, the warm air rises- this makes it cool so it starts to condense - it creates frontal precipitation 2. Topography - when warm air meets mountains, it is forced to rise - this makes it cool so it starts to condense - it creates orographic precipitation - a good example is the Pennines -why Manchester is so wet 3. Convection - the sun heats up the ground (solar radiation) and moisture evaporates - as the air gets higher it condenses - this results in convective precipitation
What is a drainage basin?
An open, local hydrological cycle. A rivers drainage basin is the area surrounding the river where the rain falling on the land flows into that river. This are is also called the rivers catchment.
What is a watershed?
The boundary of a drainage basin - any precipitation falling beyond the watershed enters a different drainage basin
What are the inputs of a drainage basin?
Precipitation includes all the ways moisture comes out of the atmosphere. Precipitation is mainly rain, but it also includes other types like snow, hail, dew and frost
What are the storages of a drainage basin?
- Interception is when some precipitation lands on vegetation or other structure, like buildings and concrete or tarmac surfaces, before it reaches the soil. Interception storage is only temporary because the collected water may evaporate quickly, or fall from the leaves as through fall 2. Vegetation storage is water that’s been taken up by plants. It’s all the water contained in plants at any one time. 3. Surface storage includes water in puddles (depression storage), ponds and lakes. 4. Soil storage includes moisture in the soil. 5. Groundwater storage is water stored in the ground, either in the soil (soil moisture) or in rocks. The water table is the top surface of the zone of saturation - the zone of soil or rock where all the pores in the soil or rock are full of water. Porous rocks (rocks with loads of holes in them) that hold water are called aquifers. 6. Channel storage is the water held in a river or stream channel.
What are the flows of a drainage basin?
1) Infiltration is water soaking into the soil. Infiltration rates are influenced by soil type, soil structure and how much water’s already in the soil.
2) Overland flow (also known as runoff is water flowing over the land. It can flow over the whole surface or in little channels. It happens because rain is falling on the ground faster than infiltration can occur.
3) Throughfall is water dripping from one leaf (or other plant part) to another.
4) Stemflow is water running down a plant stem or a tree trunk.
5)
Throughflow is water moving slowly downhill through the soil. Throughflow is faster through “pipes”
-things like cracks in the soil or animal burrows.
6) Percolation is water seeping down through soil into the water table.
7 Groundwater flow is water flowing slowly below the water table through permeable rock. Water flows slowly through most rocks, but rocks that are highly permeable with lots of joints (gaps that water can get through) can have faster groundwater flow, e.g. limestone.
3) Baseflow is groundwater flow that feeds into rivers through river banks and river beds.
9) Interflow is water flowing downhill through permeable rock above the water table.
10) Channel flow is the water flowing in the river or stream itself. This is also called the river’s discharge.
What are the outputs of a drainage basin?
1) Evaporation is water turning into water vapour (see p.4).
2) Transpiration is evaporation from within leaves - plants and trees take up water through their roots and transport it to their leaves where it evaporates into the atmosphere.
3) Evapotranspiration is the process of evaporation and transpiration together. =
4) River discharge, or river flow, is another output.
What is the water balance?
Water balance is worked out from inputs (precipitation) and outputs (channel discharge and evapotranspiration).
The water balance affects how much water is stored in the basin.
The general water balance in the UK shows seasonal patterns:
1) In wet seasons, precipitation exceeds evapotranspiration.
This creates a water surplus. The ground stores fill with water so there’s more surface runoff and higher discharge, so river levels rise.
2) In drier seasons, precipitation is lower than evapotranspiration.
Ground stores are depleted as some water is used (e.g. by plants and humans) and some flows into the river channel, but isn’t replaced by precipitation.
3) So, at the end of a dry season, there’s a deficit (shortage) of water in the Month ground. The ground stores are recharged in the next wet season (i.e. autumn)
What do hydrographs show?
They are graphs of river discharge over time. They show how the volume of water flowing at a certain point in a river changes over a period of time. Flood hydrographs (also called storm hydrographs) show river discharge around the time of a storm event. They only cover a relatively short time period (hours or days, rather than weeks or months)
What is river discharge?
The volume of water (in cubic metres m3) that flows in a river per second. Measure in cubic metres per second (m3/s) or Cumecs
What is peak discharge?
The highest point of the hydrograph when the river discharge is at its greatest
What is lag time?
This is the delay between peak rainfall and peak discharge. This delay happens because it takes time for the rainwater to flow into the river. A shorter lag time can increase peak discharge because more water reaches the river during a shorter period of time.
What is rising limb?
This is the part of the hydrograph up to peak discharge. The river discharge increases as rainwater flows into the river.
What is falling limb?
This is the part of the hydrograph after peak discharge. Discharge is decreasing because less water is flowing into the river. A shallow falling limb shows water is flowing in from stores long after it’s stopped raining.
What is runoff and hydrograph shape affected by?
- Size of drainage basin - larger drainage basins catch more precipitation, so they have a higher peak discharge than smaller drainage basins. Smaller basins generally have shorter lag times because precipitation has less distance to travel, so it reaches the main channel more quickly
- Shape of drainage basin - circular basins are more likely to have a flashy hydrography than long, narrow basins. This is because all points on the watershed are roughly the same distance from the point of discharge measurement. This means lots of water will reach the measuring point at the same time.
- Ground steepness - water flows more quickly downhill in steep-sided drainage basins, shortening lag time. This also means water has less time to infiltrate the soil, so runoff is higher.
- Rock and soil type - impermeable rocks and soil don’t store water or let water infiltrate. This increases surface runoff. Peak discharge also increases as more water reaches the river in a shorter period.
What is a flashy hydrography?
A basin with rapid runoff and not much storage capacity gives a hydrograph with a short lag time and high peak discharge. The graph has steep, roughly symmetrical rising and falling limbs.
What is a subdued hydrograph?
They have gently inclined limbs, low peak discharge and a long lag time.
What is the hydrological cycle?
A closed system on a global scale moving water between the major stores in all spheres
Why is it important to keep records of river discharge patterns?
- Important in the assessment and management of water resources
- for irrigation provision
- for the design of water related structures (reservoirs, bridges, flood banks, urban drainage schemes, sewage treatment works etc…)
- flood warning and alleviation schemes
- to help develop HEP and protect ecological health of watercourses and wetlands - With the uneven and unpredictable onset of climate change, very important to keep records of discharge to help identify, quantify and interpret hydrological trends = more effective flood/ drought management
What is the water balance equation?
P = O + E + change in S
P = precipitation
O = total overland flow, river discharge
E = evapotranspiration
S = storage (in rock and soil)
Why are some storage values negative?
- precipitation levels fall significantly during spring/ summer
- evapotranspiration levels increased significantly due to vegetation growth in spring/ summer
- soil moisture utilisation during this period means less water percolates into the groundwater stores, resulting in negative values
What are the seasonal trend that fit with the positive/ negative values of storage?
• Groundwater stores are increasingly negative during late spring/summer. This is due to soil moisture utilisation.
Why is there such a huge positive storage value in September?
• Soil moisture recharge – towards the end of summer, as evapotranspiration levels fall and precipitation levels rise, groundwater stores rapidly replenish as soil water stores are filled up.
Which month has the highest “runoff as a percentages of precipitation”. Can you suggest reasons for this?
• January – frozen ground preventing infiltration. Lack of vegetation cover meaning less interception storage = decreased evaporation of precipitation.
Why do you think there was a particularly high percentage of runoff in June?
• Land use change – vegetation cut down by farmers, decreasing interception storage.
How do you work out the Spearman’s rank correlation coefficient?
- Rank your results with 1 being the highest and so on
- Find the difference between your two results
- Square the difference d’2
- Add up the squared differences
- Then use the formula to find coefficient (r)
r’s = 1 - 6(sum of d’2) / (n’3 - n)
n= number of data sets
Use n - 2 and then find that data number if the graph and compare to what you got to see if your hypothesis or null hypothesis is correct
Where is the River Eden located?
It is in North England in Cumbria. It drains water from the north-east Lake District fells along with the north Pennines and the Eden valley, it’s source is High seat spring on Mallerstag and it’s mouth is the Solway firth (into the Irish Sea). It is 145km long. It travels through the urban areas of Apple yard Penrith as well as the city of Carlisle.
How does geology cause flooding in the River Eden?
- The upland areas of the Lake District fells are mainly igneous (the Borrowdale Igneous group)
- The lowland areas are mostly sedimentary rocks such as the Penrith sandstones and limestone
How does gradient affect flooding in the River Eden?
Elevation drops from 690m above sea level at the source to 180m above sea level at Kirkby Stephen (35km down stream)
How does weather/ climate affect flooding in the River Eden?
Around 2800mm annual rainfall in the upland areas and just 800m rainfall at the mouth. SW prevailing winds being warm moist air from the Atlantic. Tropical maritime mass.
How does drainage basin shape affect flooding in the River Eden?
Carlisle sits at the confluence of the Rivers Eden, Petteril and Caldew - lots of water coming together into one point. Drainage basin is long and thin which means there are less places for this water to go - concentrated towards Carlisle.
What is carbon and why is it important?
forms more compounds than any other element. It is needed by all plants and animals to survive. The main source of carbon is the Earths interior - stored in mantle, escapes at constructive and destructive boundaries. It is found in all life forms - sedimentary rocks, diamonds, graphite, coal + petroleum(oil + natural gas)
What is organic (biological) carbon?
Is living e.g found in plants
What is inorganic (geological carbon)?
Non- living e.g. found in rocks, coal, oil and gas
Where is carbon stored in the atmosphere?
In the form of gases e.g. CO2. It is inorganic in the atmosphere. Carbon makes up 0.04% of the atmosphere.
Where is carbon stored in the hydrosphere?
Carbon dissolved in ocean water and lakes. Rich in dissolved inorganic carbon. Also stored in immediate layers of ocean and living which matter which decays.
Where is carbon stored in the cryosphere?
Stored in permafrost or permanently frozen soil. Inorganic.
Where is carbon stored in the biosphere?
Stored in living organisms - plants and trees. Organic.
Where is carbon stored in the lithosphere?
In both organic + inorganic forms. Inorganic = fossil fuels, coal, oil and natural gas, shale, carbonate based sedimentary deposits like limestone. Organic = litter, organic matter and humus/ organic matter found in soils.
Where is carbon stored in the pedosphere?
Outermost layer of the earth containing soil. Inorganic.
What is photosynthesis and how does it fit with the carbon cycle?
-It transfers carbon stored in the atmosphere to biomass.
- plants and phytoplankton use energy from the sun to change carbon dioxide and water into glucose and oxygen. This enables plants to grow
- carbon is passed through the food chain and released through respiration and decomposition
What is combustion and how does it fit with the carbon cycle?
- combustion transfers carbon stored in living, dead or decomposed biomass (including peaty soils) to the atmosphere by burning
- wildfires cause carbon flow
What is respiration and how does it fit with the carbon cycle?
- respiration transfers carbon from living organisms to the atmosphere
- plants and animals break down glucose for energy, releasing carbon dioxide and methane in the process
What is ocean uptake and loss and how does it fit within the carbon system?
-CO2 is directly dissolved from the atmosphere into the ocean. It is also transferred to the oceans when it is taken up by organisms that live in them
- carbon is also transferred from the ocean to the atmosphere when carbon-rich water from deep in the oceans rises to the surface and releases CO2
What is decomposition and how does it fit with the carbon cycle?
- decomposition transfers carbon from dead biomass to the atmosphere and the soil
- after death, bacteria and fungi break organisms down. CO2 and methane are released
- some carbon is transferred to the soil in the form of humus
What is weathering and how does it fit in the carbon cycle?
- chemical weathering transfers carbon from the atmosphere to the hydrosphere and biosphere
- atmospheric carbon reacts with water vapour to form acid rain. 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 shells.
What is sequestration and how does it fit with the carbon cycle?
- carbon from the atmosphere can be sequestered (captured and held) in sedimentary rocks or as fossil fuels. Rocks and fossil fuels form over millions of years when dead animal and plant material in the ocean falls to the floor and is compacted.
- carbon is fossil fuels is sequestered until we burn them
How can wildfires change the carbon cycle?
- wildfires rapidly transfer large quantities of carbon from biomass to the atmosphere. Loss of vegetation decreases photosynthesis, so less carbon is removed from the atmosphere
- in the long term, however, fires can encourage the growth of new plants, which take in carbon from the atmosphere for photosynthesis. Depending on the amount and type of regrowth, fires can have a neutral effect on the amount of atmospheric carbon
How can volcanic activity change the carbon cycle?
-carbon stored within the earth in magma is released during volcanic eruptions. The majority enters the atmosphere as CO2
- recent volcanic eruptions have released much less CO2 than human activities. However, there is the potential for a very large eruption to disrupt the carbon cycle significantly.
How does hydrocarbon (fossil fuel) extraction and use change the carbon cycle?
- extracting and burning (combustion) of fossil fuels releases CO2 into the atmosphere
- without human intervention, the carbon would remain sequestered in the lithosphere for thousands or millions of years to come
How does deforestation change the carbon cycle?
- forests may be cleared for agriculture, logging, or to make way for developments
- 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
How does farming practices change the carbon cycle?
Agricultural activities release carbon into the atmosphere:
- animals release CO2 and methane when they respire and digest food
- ploughing can release CO2 stored in soil
- growing rice in rice paddies releases a lot of methane
As the world 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.
How has land use changes changed the carbon cycle?
As well as deforestation the change of land use from natural or agricultural to urban is a major source of carbon:
- vegetation is removed to make way for buildings - this reduces carbon storage in the biosphere
- concrete production releases lots of CO2 and lots of concrete is used when urban areas expand
What characteristics of the Eden basin affect the water cycle?
1) Rainfall is higher than the national average in the Eden Basin, because of the relief of the area — the mountainous terrain encourages orographic rainfall. High rainfall means that lots of water enters the river channels.
2) The Eden Basin is long and relatively narrow, which increases lag time.
3)The slopes within the basin are steep. This reduces lag time and increases peak discharge.
4)The basin is made up of a number of different types of rock:
• The highest ground, to the west of the basin, is made of igneous rocks, which are impermeable (water wont soak into them). Infiltration is very slow and surface runoff is high in these areas, reducing lag time.
• Much of the basin, however, is made up of limestone and sandstone, which are permeable.
When precipitation falls in these areas, infiltration is quick and there is little surface run off, increasing lag time. The amount of water in ground stores increases.
How has farming in the River Eden affected the risk of flooding?
1) More intense farming has caused soils to become compacted, e.g. by heavy machinery or trampling by livestock. Between 2000 and 2009, there was a 30% increase in the number of cattle in the Eden Valley, meaning that much more land is likely to have been trampled.
2)
Compaction of soils reduces infiltration, so surface runoff is higher. This means water levels in rivers rise quickly during heavy rainfall, increasing the risk of flooding.
3)
Grazing in upland areas, e.g. hill farming of sheep, has also reduced the amount of vegetation that can intercept rainfall, resulting in more water reaching rivers.
How has construction in the river Eden affected the risk of flooding?
1)Although the majority of the Eden Basin is rural, built-up areas have increased. Many new housing estates have been built in and around Carlisle in recent years, e.g. the Eden Gate development to the north of the city, and there are plans to develop a huge ‘garden village’ to the south of the city, including up to 10000 new homes.
2) Surfaces in built-up areas tend to be impermeable, which reduces the size of infiltration flows and greatly increases the size and speed of surface runoff flows.
3)Some new developments, particularly near Carlisle, have been built on floodplains. This has created a flood risk co property and has required the construction of flood defences to protect homes. Building on floodplains can cause flooding downstream as water that would naturally infiltrate on the floodplains flows downstream instead.
How has deforestation in the river Eden affected the risk of flooding?
1)
Deforestation has taken place in the basin for thousands of years, e.g. to provide timber, and land for farming. Much of the original forest cover in the Eden Basin has now been removed, giving way to large areas of open grassland and heathland.
2)
Trees increase infiltration and decrease runoff, so fewer trees means more runoff, flashier flood hydrographs and a greater risk of flooding.
How did Storm Desmond affect the Eden Basin?
1) In December 2015, Storm Desmond caused devastating flooding in Cumbria. Some of the worst flooding occurred in the Eden Basin.
2) In some areas of Cumbria, there was record rainfall. In Shap, a village in the Eden Basin, 262.6 mm of rain fell in 48 hours between the 4th and 6th December. That’s nearly 50 mm more than the average rainfall for the whole of December.
3) Appleby-in-Westmorland and Carlisle were particularly badly affected. More than 2000 properties were flooded in Carlisle alone, leaving many people homeless.
4) The hydrograph shows the River Eden’s response to Storm Desmond. The gauging station that recorded this information is located at Linstock, just upstream of Carlisle.
What is the enhanced greenhouse effect?
The process that is currently causing global warming as abnormally high levels of greenhouse gases are being produced by humans, trapping radiation from the sun, causing global warming and leading to climate change.
What is radiative forcing?
Refers to the difference between incoming solar radiation absorbed by the Earth and the energy radiated backout into space. Increased in recent years, leading to more near being trapped.
What are the impacts of increases in global temperatures due to alteration of the carbon cycle on the water cycle?
Greater levels of evapo transpiration,may make summer storms more likely but decrease the amount of rainfall in summer on average, yet increase the average winter rainfall
What are milankovitch cycles?
Vostok ice core data from Antarctica suggests that in the past temperature change has occurred before carbon dioxide levels have risen, offering a slightly different explanation for historical global warming. it is possible that variations in the Earths orbit cause periods of time where we experience a greater hearing effect from the sun, increasing global temp. This causes glaciers to melt and therefore increases flows in the carbon cycle, allowing more carbon dioxide to enter the atmosphere = positive feedback. The quantity of freshwater flowing into the oceans increase, causing temperature fluctuations between the. Earth’s two hemispheres. As the oceans become warmer they release more carbon dioxide into the atmosphere
Why aren’t milankovitch cycles widely agreed on?
As any slight systematic errors in the data collection would affect the overall conclusions of the study.it is thought that it is natural that carbon dioxide levels + temperature increase during interglacial periods.
What are the impacts of the carbon cycle on regional climates?
Tropical rainforests: - high rates of photosynthesis and respiration in forests lead to greater humidity, cloud cover+ precipitation. - deforestation reduces photosynthesis+ respiration, further reducing humidity and cloud cover and decreasing precipitation
Oceans: _warmer oceans cause more plankton growth and through plankton chemical production, cause clouds to potentially form. - warm oceans also store less carbon dioxide, as carbon sequestration is dependent on a cooler ocean. This means higher temps could lessen the effect of oceans as carbon sinks.
How has the carbon cycle impacted the land?
Research is lacking and unclear because it has been done over a very short period of time.
Land is one of the most important facets of the carbon cycle, because carbon moves between the lithosphere, cryosphere and biosphere.
This means that there are numerous variables, both human and physical, which could results in positive and negative feedback mechanisms.
Photosynthesis
This is an example of a negative feedback mechanism:
Carbon in the form of organic matter is essential for plant growth and production of food.
Valuable source of energy in the form of wood and fossil fuels
More Co2 available results in more photosynthesis and plant growth.
More Co2 has also led to an increased growing season for plants
More Co2 has increase temperatures which then leads into increased decay of organic matter.
Permafrost
Permafrost is a store of carbon on land, which are especially sensitive to temperature change. It covers 22% of the land surface and is defined as the subsurface layer of the soil that remains frozen for 2 consecutive years.
When temperatures increased, permafrost starts to thaw and the organic material restarts the decaying process by microbial activity, releasing carbon into the atmosphere.
This results in a positive feedback loop as more carbon means warming continues, warmer temperatures means more thawing of permafrost
Current research estimates that permafrost in the northern hemisphere holds 1,672 GtC. If just 10% of this were to thaw, it could release enough Co2 into the atmosphere to raise temperatures by an additional 0.7ºC by 2100.
How has the carbon cycle impacted the oceans?
Oceans cover just over 70% of our planets surface and are a significant carbon sink, containing an estimated 38-40,000 GtC making it Earth’s 2nd largest store.
It is believed that oceans have absorbed 38% of anthropically produced Co2, which provides an important buffer helping to regulate carbon concentrations on land and in the atmosphere.
It is difficult to predict the precise rate, magnitude and direction of change of Co2 uptake and how it affects acidity, salinity, storminess and nutrient enrichment. It is even more difficult to map these effects on a local scale.
Carbon can be converted into calcium carbonate, which is used by some marine organisms to build shells.
Ocean acidification
30% of the released Co2 is diffused into the ocean through direct chemical exchange.
This creates a carbonic acid, making the ocean less alkaline
Since 1750, the pH of the oceans surface has dropped by 0.1, but the impact on ecosystems is largely unknown
Carbonic acid reacts with carbonate ions in the water to form bicarbonate.
However, animals like coral and phytoplankton need those ions to make their shells. Less carbonate available may mean shells become thinner and more fragile.
Coral reefs provide food and livelihood security for 500 million people. A fall in marine biology threatens food security.
More optimistically though; the more acid seawater is, the better it is at dissolving calcium carbonate rocks (chalk and limestone). Over time, this allows the ocean to soak up excess co2 because the more acidic water will dissolve more rock.
Melting sea ice
Melting ice is part of a feedback mechanism: Highly reflective ice is replaced by more absorbent water. This then absorbs more sunlight which in turn amplifies the warming.
Sea ice also provides a habitat for algae. The loss affects the food chain from krill to bears.
Seals and bears can no longer travel on the ice.
Huge consequences for sea level rise
Sea level rise
Since the 1990s, sea levels have risen at a rate of 3.5mm/year.
Melting terrestrial ice: warmer temperatures mean increased rate of ice melting in summer and reduced snowfall in winter
This results in a imbalance net gain of water entering the ocean.
Thermal expansion: When water heats up, it expands:
About half of the past century’s rise in sea level is attributed to the oceans having a greater volume.
If continued, oceans are expected to rise between 0.8 and 2mm per year by 2100.
Ocean Salinity
Decrease in salinity in the deep North Atlantic
More freshwater being added to the ocean
Slowing down of the large-scale oceanic circulation in the NE Atlantic.
How has the carbon cycle impacted the atmosphere?
Increasing atmospheric Co2
Proportion is now 400ppm, higher than at any change in the last 800,000 years and is set to increase further.
This has led to enhanced greenhouse effects.
As much as 20% of additional Co2 will remain in the atmosphere for many thousands of years.
Without Co2, the earth would be a pretty chilly -180ºC, although with too many Earth would be like Venus; 400ºC.
Enhanced greenhouse effect is causing radiative forcing.
Carbon stored by vegetation has a significant effect on the atmosphere, whether deforestation (carbon source) or afforestation (carbon sink)
Radiative forcing
Energy is constantly flowing from the atmosphere in the form of sunlight
30% of this sunlight is reflected back into space
The rest is absorbed by the planet
Some of this absorbed energy is radiated back as inferred energy
If the balance between the incoming and the outgoing energy is anything other than zero, warming (positive) or cooling (negative) will occur.
The measure of it being out of balance due to human activities (radiative forcing) is measured in watts/m2
Radiative forcing has increased due to greenhouse gas emissions and changing albedos due to land use changes
Regional climate
Vegetation removes Co2 and releases water and oxygen
Regions with dense vegetation (tropical rainforests) experience high rates of photosynthesis and respiration. This increases the levels of humidity and cloud cover, which in turn can have regional climate and rainfall.
Widespread deforestation cause areas to become drier and less humid. Less trees means less photosynthesis.
Volcanic eruptions release Co2 along with other gases into the atmosphere. This absorbs more incoming radiation from the sun and can lead to a cooling effect.
What are the main stores and transfers of water in the rainforest?
- Water is lost to atmosphere through evapotranspiration
- Precipitation
- Stored on leaves surfaces
- Water in plant tissue
- Drip flow
- Evaporation from soil
- Stored as groundwater + surface water, puddles
- Stored in trees + roots - take water from soil
- Atmospheric moisture
- Stem flow
- Interception storage
What is the average rainfall and temperature in the Amazon?
3800mm per year
28 degrees Celsius
Why is there so much rainfall in the Amazon?
- The ITCZ (inter tropical convergence zone) is the point where the 2 Hadley cells meet at the equator
- here air pressure is low so evapotranspiration happens in huge amounts which therefore causes a lot of rain. Therefore the rainforest is hot + wet which lead to rich vegetation and biodiversity
How has the change in the political situation (since 2019) affected rates of deforestation - why?
Bolsonaro was elected as president in 2019 and since then the rates of deforestation have increased rapidly. Because he wanted more hydroelectric power so flooded a lot of the Amazon as well as wanting more agricultural land. Since then there has been a 35% decrease in deforestation in Lulas first 6 months of presidency in the Amazon.
How has evapotranspiration been impacted in the Amazon?
Evapotranspiration is reduced so atmosphere is less humid. With less trees rainfall goes straight to floor + surface flow occurs so soil becomes dry + baked as it is exposed to the sun. Reduced evapotranspiration in cleared areas = air is less moist = less cloud cover. Removal of trees through slash + burn = evaporation of water
How has rainfall been impacted in the Amazon?
Particles resulting from burning of trees increases the density of airborne aerosols around which water vapour condenses. Smaller droplets occur in these clouds which are too small to precipitate so = less local rainfall. Forests emit salts + organic fibres along with water. Act as condensation nuclei - their loss inhibits the formation of clouds and therefore rainfall. Any moisture that does evaporate forms shallow cumulous clouds - no rainfall.
Describe the process of positive feedback when extensive deforestation has occurred?
When extensive deforestation occurs there is less water in the Amazon as the water is leaving the Amazon through the river channel, this then causes evapotranspiration to decrease which in turn decreases the amount of precipitation as there is less water vapour available in the atmosphere. Because of this there is less water getting to the river channel through overland flow and through flow. This therefore means there is less water evapotranspirating - amplifying this positive feedback.
What are the global climate implications from deforestation in the Amazon?
Deforestation has serious implication for the future discharge of the Amazon river. It is likely that significant falls will happen through the entire Amazon basin. Reduced atmospheric moisture will be based throughout the entire region via atmospheric circulation = changes to global precipitation patterns.
What are the main stores and transfers of carbon in the Amazon rainforest?
- Photosynthesis - take in CO2
- Plant and animal respiration gives out CO2
- Leaf litter
- Respiration by decomposes
- Runoff of c in water
- Root cell respiration and death
- In trees and roots
What is the impact of burning on the carbon cycle?
- releases CO2 + hydrocarbons from trees
- contributes to global warming through greenhouse gas emissions as trees are being removed so can’t take in CO2 anymore
- Blackened stumps + ground surfaces are carbonised wood - rotting of them releases carbon into atmosphere
- when land burned 30 - 60% of carbon is released into the atmosphere
What is the impact of replacing rainforest with alternative uses on the carbon cycle?
- Crops + pasture - reintroduces stores + flows although much less effective
- now becoming a carbon source not a sink
- in a typical year Amazon absorbs 2.2bn tonnes of CO2 whilst emitting 1.9bn tonnes of
- nothing you replace it with will absorb as much carbon as the rainforest will
What does antecedent conditions mean?
This refers to the weather conditions in the period preceding a storm event.
Several weeks of prolonged, heavy rainfall will mean that a drainage basin reaches saturation capacity very quickly after a storm event.
What is evapotranspiration?
The sum of evaporation and transpiration
What is water abstraction?
Removing water from underground (aquifers – underground reservoirs)
What is lag time?
Length in time between the peak rainfall and peak discharge
What is discharge?
Amount of water in the river at a particular point in time (measured in cumecs)
What is meant by river regime?
A river regime shows how the discharge of a river varies over a longer period of time — usually a year.
•Be aware of the factors that change the speed, and amount, of precipitation that reaches a river. Think of a river as system with:
•Inputs
•Stores
•Transfers
How can deforestation alter flows of water in the basin?
Decreased canopy - decreased interception – decreased evapotranspiration – increased surface runoff
Bare soil – soil compaction - decreased infiltration – decreased throughflow - increased surface flow
Farming practices as a result of the deforestation – soil compaction – reduced infiltration – increased surface run off
Water abstraction (removal of water) for irrigation – dry and compacted soils – reduced infiltration – increased surface flow
Increased flow – reduced storage
Water from roots is released = increased humidity – increased precipitation – antecedent conditions – saturated soils - increased surface flow
Why does deforestation cause variation in river regimes in Amazon?
About half of the precipitation in the Amazon does not reach the river as it is intercepted by the canopy layer and then evapotranspiration occurs releasing it back into the atmosphere as part of a closed system loop. Only about 30% usually reaches the sea. However, when the trees are deforested, the top soil is quickly removed due to the heavy rain which further reduces infiltration and throughflow. Therefore surface flow increases and so does the river discharge some times leading to flash floods.
Why do season changes/ natural variation in rainfall cause variations in river regimes?
The discharge starts to increase in November and December as the precipitation increases. Also, the ground may be dry and compact as a result of dry hot weather during the summer months, therefore reducing the amount of infiltration and increasing surface flow. As it is the fastest route back to the river, the discharge therefore increases.
Why does land use change (agriculture) - also links to water abstraction for irrigation cause variations in river regimes?
Farmed crops often intercept less precipitation than natural vegetation cover too. Subsequent precipitation can exceed infiltration capacities of the soil resulting in increased overland flow.
Drainage patterns are changed too. Farmers intentionally dig drainage ditches within and around their fields to prevent water logging of plants. This means that water moves initially via overland flow and then via small channels into rivers, affecting both the hydrograph and annual regimes of those rivers.
Agriculture often reduces vegetation cover and soil compaction from machinery can occur. Both of these can reduce the amount of water that infiltrates into the soil and therefore increase run off.
Why does mining/ mineral extraction cause variations in river regimes?
Mining leads to large scale vegetation clearance which again reduces evapotranspiration and convection rainfall. This may reduce localised precipitation which could reduce the river discharge. However, it is more likely that without vegetation, there will be reduced interception and infiltration, therefore increasing surface flow, reducing the lag time and increasing the river discharge.
There is also the risk of the river water becoming contaminated with pollution and/or iron ore sediment. The river bed could also become full of silt/sediment which would change the capacity of the river.
