changes in carbon cycle Flashcards
carbon levels over years
fluctuated
carbon level inc so does temp
400,000yrs ago co2 spiked 280ppmv and temp spiced 4degrees in antartic
carbon levels relatively similar over years
projected 270ppmv to 400ppmv
effect cold conditions
chemical weathering lees effective as cold transfers less carbon so more is stored
less forest cover
less carbon transfered
more stored
decomposers less effective
less transfered to soil
less stored
less water flow
less sediment tranfer
less build up ocean floor
less transfer
more stored
more stored
less transferred
warm conditions effect
permafrost meted carbon transfer inc
less stored
more water flow to coean
more sediment build up
more transfer
less stored
less stored
more tranferred
natural causes change in carbon cycel
natural change
wildfire
volcanic activity
orbital change
climate forcing effect
Surface of sun has sun spots (storm) solar flares happen which leads to small increase in temperature on earth (decades)
Short term change example
11 years between peak and low of sunspot activity
Late 17th century there was 70 years few sunspots (maunder minimum) matches with lower temperatures – river Thames froze over and had fairs
different glacial periods
Interglacial = warmer
Glacial = cold
At end glacial period its warmer so melting so more co2 to atmosphere – greenhouse effect (positive feedbach)
orbital forcing
eccentricity
obliquity
precession
1000s of years
change orbit
what is eccentricity
Sometimes circular orbit sometimes elliptical orbit changes every 100,000 years
Circle earth same dist sun so gets same solar energy through year
Elliptical distance changes sometimes close so more solar energy or further away so get less
obliquity
earths rotating on tilted axis this angle changes – more vertical or tilted changes between every 41,000 years
Caused gravity large plants like Jupiter and Saturn pulling on earth
Determines length and strength of seasons
precession
earth is wobbling, takes 26,000 years to complete one wobble, direction earth axis points slowly changes
Effects how much solar energy each hemisphere receives at different times of the year, responsible timing of seasons
Combines together cause long term changes to earths climate
volcano impact
1991 eruption gave off ash and dust and gas
particles reflected the solar radiation
avg global temp fall by 0.5 degrees for 2 years (short term change)
Volcanoes emit 130-180 million tonnes co2 per year in comparison to humans 30billion tonnes from burning fossil fuels
Lava has silicates that can weather
natural change impact
carbon always moving
global climate fluctuates
influence glacial intetglacial
wildfire impact
Commonly by lightning strikes
Localised but has region impact
Indonesia many wildfires that burnt for month in 2003, many in Australia
Cover wide area (smoke spread across southeast Asia from Indonesia)
Released lots co2 into atmosphere
Turned forest to carbon source as combustion returned carbon to atmosphere and to pedosphere as charcoal
reason for post glacial warm
Believe 90% post glacial warming occurred after rising atmospheric co2
Nobody totally convinced on clear cut reason/pattern
Fairy certain anthropogenic factors have sped up co2 level and higher temp
human changes carbon cycle
cement manufacture
farming
land use change
urban growth
natural source carbon
ocean atmosphere exchange which accounts for 42.84%.
Plant and animal respiration accounts for 28%
soil respiration + decomposition also accounts for 28%.
The smallest store is volcanic eruptions is 0.03%.
human sources carbon
fossil fuel usage which is 87%
Land use change is the second biggest of 9%
industrial processes 4%
fossil fuels and co2 conc data
fossil fuel concentration has increased steadily
- highest concentration in summer and lowest in winter
in total the co2 concentration has increased in general
In 1960, co2 concentration was 315ppmv and then it rose to 370ppmv in 2000
increased to 400ppmv in 2015
overall increase in 85ppmv over 55 years.
shrimpling farm
emit 150 tonne carbon from fuel from machines
nitrous oxide emissions from crop residues and green manure
250 sheep realse 6% farm emissions (methane)
650 Ha arable farm
60% sequested from woodland
20% field margin
18% hedges
2% orchards
land use change - deforest
forests cleared
sometimes burnt
releases carbon to atmosphere
less is stored
clearing of the forest
accelerates decay of wood and litter and organic carbon
more is released to the atmosphere
less is stored
less interception
water cannot infiltrate
soils dry
vegetation cant grow
so less carbon taken in from atmosphere
180 tonnes of carbon per hectare are taken up by photosynthesis of above ground biomass
so deforestation means more carbon is staying in the atmosphere.
tree dies it releases carbon however this is slow process so new vegetation can grow and take up this carbon becoming carbon neutral.
how does cement cause co2 production
clinker key component cement
calcium carbonate heater to make clinker
every 10000kg cement 900kg co2 released
used in construction as affordable and strong
farming impact carbon
10% carbon emissions
artifical fertilisers source carbon emissions
soil ploughed
air mix in
microbial activity inc
more organic matter decomposed
more co2 to atmosphere
livestock produce methane
US cattle emit 5mill tonnes methane each year
processes in rice paddles generate methane
deforestation facts
13 million Ha forest cut a year
Trees cut and burnt or used for building
3% of forests were lost between 1990 and 2005
at a rate of 200km2 per day – meaning rainforests could vanish completely within 100 years.
urbanisation impact
As cities grow need more land
The CO2 emissions from transport, industry, domestic use and cement manufacture for buildings have all increased.
In 2012, cities responsible for 47% of global carbon emissions.
Replacing open countryside with concrete and tarmac is a major change in land use
- significant impact on the local carbon cycle as important stores are either replaced (vegetation) or covered up(soils) with impermeable surfaces.
2013, global CO2 emissions from fossil fuel use and cement production were 61% higher than in 1990 and 2.3% higher than 2012.
