Carbon Cycle - Change - N&H Flashcards
Natural climate change
Several glacial periods intercepted by inter-glacial periods
When temp inc , carbon inc
Both fluctuate - Invadmum
Eg 320,000 years before present - temp = 4 degrees and 300ppm of atmospheric carbon
Eg 220,000 ybp temp -3 and 250ppm
Present day - proportion significantly increased between temp and CO2
Eg present day: 0 degrees and 390 ppm of atmospheric carbon
Impact of cold conditions
Weathering
Chemical weathering process would have been more active as cold water can hold more CO2
Forests-
forest coverage would be v diff bottom total area and geographical location —> affects the significance and distribution of processes like photosynthesis and respiration
Decomposers -
Would have been less effective so carbon transfers to soil = reduced
Impact of wildfires
Had a larger impact is past as more vegetation (biosphere) and no means to extinguish
Cabon transferred from biosphere to atmosphere through combustion
Release lots of CO2 in atmosphere, causing spike in trend of carbon emissions since 1950s
Wildfires can turn forests from being a carbon sink to source, as combustion returns huge quantities of carbon back in atmosphere
Natural GHE accelerated as more carbon in atmosphere trapping energy - temp increases - permafrost melts
More carbon released from lithosphere to atmosphere
GHE accelerated further
Positive feedback
Impact of warm conditions
Interglacial periods
Caused by GHE inc carbon and other melt gases stored in permafrost released in atmosphere
EGE
In global warming
Positive feedback
Impact of volcanic activity
500,000-200,000 years ago, volcanic activity was greater
Carbon transferred from lithosphere to atmosphere by process of subduction and combustion
Natural GHE accelerated further - positive feedback
Volcanic activity returns to atmosphere, carbon trapped for millions of years in rock deep with earth’s crust
At present, volcanoes emit between 1-4 million tonnes of carbon per year
During paleolithic era - volcanoes more active than today - more CO2 in atmosphere - remained for long time
What is eccentricity
Tilt
Precession
Eccentricity - when the earth’s orbit changes - takes 10,000 years
Tilt - the tilt of the earth on its axis also varies and the earth wobbles on its axis 22-24 and a half degrees -> takes 41,000 years
Precession- wobble on earth’s axis - takes 24,000 years
Impact of milankovitch cycle
Eccentricity, tilt and precession results in:
When earth is closer to sun, temp will be warmer -> interglacial periods
Long term change
10s of thousands of years
Temp rises - frozen stores of carbon released in atmosphere - inc GHE - warmed - positive feedback - long term change - 10s of thousands of years
Impact of icebergs
Could be responsible for process that absorbs up 2 20% of carbon in southern oceans carbon cycle
Researchers say meltwater from ice blocks take up CO2
When it does - sinks to ocean floor, locking away any carbon it absorbed
Estimated that giant icebergs account for 10-20% of downwelling carbon going from surface to deep (southern) ocean -> negative feedback - more important than previously thought
Phytoplankton at sunlit surface of sea = central role in sequestration of carbon over millennia to affect the atmospheric concentration of GHG- so the earth’s climate
More storage of carbon in deep oceans reduce amount of carbon stored in atmosphere
Human factors impact
Main factor = fossil fuels as SOE
about 10% electricity in U.K. from burning fossil fuels
Natural gas is burnt more compared to oil and coal in U.K.
Keeping curve shows annual fluctuations in carbon - but overall trend shows increase in CO2 in atmosphere
Increase in 90ppm in carbon from late 1950- late 2018
How far are humans responsible
Gov records show burning fossil fuels and removing vegetation - make CO2 ppm around 500ppm - now 406
But some gov esp LIC would not have record of this, but they are not industrial countries so wont have produced large amounts of carbon
The difference in carbon expected but actually in the atmosphere did because of carbon in the forests and oceans
Carbon produced by burning fossil fuels - different proportion of isotopes from CO2 in atmosphere -> know extra carbon
