Ecosystem Feedbacks Flashcards
What is an Ecosystem feedback?
- It is something which is a positive feedback which exacerbates the original process
Explain the carbon cycle feedbacks due to rising temperature?
- We are warming the earth’s climate
- This is causing permafrost to melt within the Artic
- Resulting in increased methane released which was stored within the permafrost
- Hence the warming is exacerbated
Explain Albedo feedbacks due to rising temperatures
- We are warming the earth’s climate
- resulting in shorter periods of snow cover + reduced snow+ice cover
- Resulting in increase radiation which can be trapped at the land surface
- Resulting overall in increased warming
What is a source in terms of carbon cycle feedbacks
- Net release of GHG into the atmosphere
- e.g. biomass burning, wetland CH₄ emissions
What is a sink in terms of carbon cycle feedbacks
Net uptake of a GHG
e.g. afforestation, CO₂ uptake by the oceans reducing atmospheroc concentrations
What is carbon storage in terms of carbon cycle feedbacks
- If ecosystem sinks are greater than sources carbon accumulates in ecosystems
- Slow decomposition in cold wet soils results in large carbon storage at high latitudes
How can elevated CO₂ affect carbon cycle feedbacks?
What can limit this however?
- Increase plant photosynthesis (more CO₂ sequestered)
- Increased carbon stored in vegetation
- BUT low nitrogen availabuluty will limit carbon storage on land
How can elevated temperatures affect carbon cycles feedbacks?
- Increased plant and soil respiration (more CO₂ given out)
- Reduces terrestrial carbon store
Explain what these graphs demonstrate
In the southern ocean there is large carbon uptake linked by the consumption and high nutrient concentrations there
There is also more carbon sequestration on land in the northern hemisphere due to high amounts of rainfall and not being too cold
Following these graphs (mainly on the right)
Where would we expect to find the highest amounts of biomass globally
In the high northern latitudes
Natural transfers of CO₂ are x times greater than those due to human activity
natural transfers (black) of CO₂ are 20 times greater than those due to human activity (red)
What does the following graph show?
The sink strength of net land CO₂ sinks has a tendency to be increasing over the measurement period
True or False?
The net fluxes of carbon dioxide, methane and nitrogen oxide are all equal
False
The fluxes vary from location to location
With reasons due to temperature or moisture levels affecting fluxes
How can anthropogenic activity cause disruption to the global carbon cycle
- Land use changes - short term imbalances (terrestrial flux)
- Deforestation
- Agriculture
- (positive feedbacks)
Thawing of permafrost due to warming will…
release frozen carbon
which will increase CH₄ emissions
(50-250 GtC with RCP8.5 scenario compared with 6.4 GtC/yr of fossil fuel emission)
Huge impacts
The tipping point is expected to be hit with carbon sinks with future climate change
What is expected to occur?
The decline of global soil and vegetation sinks by 2100
(suggested reasons like drought, fire, heat stress, increased CO₂ from the soil)
List some environments which are affected by GHG fluxes (CH₄, CO₂) with climate change
- Forests (growth or fire/insect damage)
- Lakes and Ponds with vegetation
- Phytoplankton
The following region can store over 140KgC/m²
Why is this value so high
- They are areas which are high in peatlands (due to cold conditions and relatively high levels of precipitation)
How is degradation of permafrost linked vegetation changes?
Vegetation succession linked to degradation of permafrost (this process has been suggested to have been occuring for decades)
Moving to the right, the active layer become shallower, moisture content increases
Researchers can use satellite InSAR data to measure subsidence
This shows?
Areas of subsidence corresponding to degrading areas
The difference in subsidence amoung vegetation ypes t
e.g. going from 2016-2021 there is degradation, increased water logging and methane will be produced at the surface
What two factors control the degree of methane emission from degraded water logged peatland surfaces?
- Flooding: Highly heterogenous in degrading areas, hots spots of emissions
- Roots: however oxygen inputs reduce emissions as it causes labile substrates to be pushed below ground
What would be the process for scalling from individual sites to regional sites of the pan-Arctic?
- Field CH₄ measurements, UAV and satellite mapping to estimate CH₄ emissions to Northern Sweden
- Parallel ground and satellite data collection from permafrost peatlands around the pan-Arctic
- Extrapolate the resulting algorithms to the pan-Arctic
