Effects Of Changing Carbon Budget - impact on land Flashcards
How have co3 levels varied. Give evidence?
500 million years ago atmospheric co2 was 20 times higher than present values.
It dropped and rose again 200 million years ago to around 5 times higher than present levels.
What can only calculate the effects of changing levels of carbon?
A computer model.
Only predict possibilities not probabilities.
What has been concluded from the impact of atmospheric co2 on the land?
Due to studying of the land being over short period and the fact many other variables impact the land.
Both human and physical.
Unclear to say impact.
How much co2 does the permafrost in northern hemisphere hold ?
1,672 GtC.
If just 10% of this was to thaw it could release extra co2 to increase temps by 0.7 degrees in 2100.
Name 3 land use decisions?
Agriculture.
Farmland.
Wildfires.
Agriculture in effect of changing carbon budget
Agriculture more intensive.
More crops from less land increase co2 take up.
How do wildfires effect carbon budget.
More wildfires being extinguished.
Leads to build up of woody material storing carbon.
Fires/ deforestation also lead to increase in co2
How does farmland effect carbon budget?
Farmland abandoned in mid latitudes in early 20th century.
Replaced by trees which store much more co2 than crops.
How does an increase in temp lead to positive impacts for plants?
Increase in growing season.
More plant growth / evapotranspiration.
More co2 into biosphere
However this needs water so growth can be limited by water availability. Thank
How does an increase in temp lead to negative impacts for plants?
Warmer lane means tundra also warms up.
Increases rate of decay of accumulated dead organic matter meaning more co2 methane released.
How can mode co2 in atmosphere be positive on plants?
More photosynthesis and plant growth.
This is called carbon fertilisation
