Wetlands And Carbon Cycling Flashcards
(39 cards)
Methane is the …. most important greenhouse gas after …
Second
CO2
How much human induced radiative forcing is methane responsible for?
18%
How much more global warming potential does methane have compared to CO2
25 x
Anthropogenic sources of CH4 emissions to atmosphere?
Livestock Biomass burning Landfills Waste management Fossil fuel production Rice agriculture
Natural source of global CH4 emissions to the atmosphere?
Freshwater aquatic ecosystems
Wetlands
….. are the single largest natural source of CH4
Wetlands
What are rice fields
Agricultural wetlands with the same controls in CH4 emissions as natural wetlands
What are wetlands?
Areas of land covered in, or saturated by water nearly all year round
Present in every climatic zone - from polar to tropics, from Hugh altitudes to dry regions
Examples of wetlands?
Mangroves Peat lands Marshes Rivers Lakes Deltas Floodplains Flooded forests Rice fields Coral reefs
Water inflows in wetlands/peat lands
Rainfall
Surface water
Groundwater
Water outflows in wetlands and peat lands
Evapotranspiration
Surface water
Groundwater
Water balance =
Inflow - outflow
Explain the term hydrological regime
Describes the pattern of water storage and movement with and across the wetland boundary
It often has strong seasonal patterns arising from rainfall and sunshine intensity
What is the hydrological regime determined by?
- timing of the presence of surface water
- how often the wetland floods and dries (frequency of flooding)
- the length of wet and dry periods (duration)
- how far the water spreads (extent)
- the depth of the surface water
- how far the water is below the ground (depth of water table)
- the waters source (rainfall, groundwater, river)
- the inter-annual variability of water levels
What retirements the community of vegetation that will grow in a wetland?
The hydrological regime of the wetland
Wetlands changes occur due to changes to the…
Wetland itself
Catchment surrounding the wetland
Climate change
To accurately estimate the importance of wetlands for global emissions we need accurate data on…
The distribution of different wetland types
The areal coverage of different wetland types
Atmospheric methane concentrations in 2000-2007
Constant atmospheric CH4 concentrations
i) increases in anthropogenic CH4 emissions
ii) dry conditions in northern wetland resulting in low CH4 emissions
Atmospheric methane concentrations in 2007+
Atmospheric CH4 concentrations increase in response to
i) increases in anthropogenic CH4 emissions
ii)temperature increases leading to increase in emissions from;
Northern wetlands (2003-207)
Tropical wetlands (2007/8)
Boreal wetlands
Uncertainties in the magnitude of CH4 emissions from wetlands
- controls of CH4 production, consumption and transport have not been adequately captured in models
- limited number of observations of fluxes and their associated environmental variables
- wetlands themselves are poorly mapped and very heterogeneous
Peat lands
Wetland types including moors, bogs, mires, peat swamp forests and permafrost tundra
- characterised by water logged soil made up of dead and decaying plant material
- peatlands represent 50% of earths wetlands and cover 3% global land area
Importance of peatlands?
Water - offer flood protection by absorbing rain and releasing water slowly
Food - herding cattle, catching fish and farming
Species - home to many rare and critically endangered species
Climate change - contain twice as much carbon as worlds forests however also a significant source of greenhouse emissions
Peatlands and carbon storage ?
Carbon storage is an important ecosystem service provided by waterlogged, undisturbed peatlands where organic carbon input rates > organic carbon decomposition rates.
How much carbon do peatlands contain?
500-700 billion tonnes of carbon
- more than the worlds tropical forests (360 Gt)
- more than half of the carbon stored in atmosphere (750 Gt)
