ECEC - arctic ecosystems Flashcards
describe polar amplification
- snow and ice melt revealing more dark surfaces which absorb heat
- Positive feedback loop
- Lack of plants in the arctic – reduced evapotranspiration – this is a cooling mechanism – more heat goes into warming instead of cooling process - the atmospheric layer that has to warm in order to warm the surface is shallower in the arctic
- as sea ice melts, solar heat is absorbed by the oceans is more easily transferred to the atmosphere
- alterations in atmospheric and oceanic circulation can increase warming
describe permafrost
permanently frozen ground (at-least 2 consecutive years) which stores carbon as peat and methane - more than twice as much carbon than the atmosphere - stores organic soil carbon
what can melting of permafrost cause?
sunken and misshapen grounds when ice melts, trees falling over from melt = ‘drunken forest’
why is warming concentrated in the arctic?
because it is greatest in high northern latitudes
describe the positive feedback of permafrost thaw
- At first plants are able to get more nutrients and water helping them to aid growth
- Therefore initial stage of thaw can cause increase of co2 uptake
- Over time overall there is more carbon being released than taken in
- As lower ground gets saturated with water a wetland could be created and more methane is released
what is done to help reduce the effects of permafrost thaw?
- Roads must be kept clear of snow in winter to allow permafrost to get really cold and reduce effects of heating of the dark surfaces during the summer
- Heat exchangers can also be used to remove heat from land and keep permafrost as cold as possible to avoid slumping
when is snow cover loss fastest?
spring/ early summer
what is a growing season?
snow free period - 2 weeks longer now than it used to be
what is the consequence of the now 2 week longer growing season?
increase in tundra ecosystem productivity and respiration
what is arctic greening and its consequence?
increased plant growth of more productive plants -Increase in carbon sequestered by greening tundra
what is the consequence of loss of arctic sea ice and the timing of melting?
- more heat absorbed by Earth’s surface
- Big consequence is loss of shiny surface and exposed ocean to absorb heat
- Big effects on marine ecosystem
- Changes in time of melt and freeze each year impacts timing of food availability
what are the ecological consequences of sea ice decline?
- Affects availability of ice-associated zooplankton and forage fish (critically important for sea birds, marine mammals and fish species)
- Sub-arctic species are expanding northward to where it is colder which then compete with the arctic species – puts pressure on them for lack of resources and competing for the same niches
what are the ecological consequences of sea ice melting for pinnipeds?
Pack ice breeding seals will experience reproductive failure more frequently – late winter/ early spring breeding habitat becoming less stable
what is the effect of sea ice reduction on polar bears?
- Reduced seals effects polar bear populations – shift in trophic interactions
- As sea ice thin – more fractured and labile so polar bears need to swim more and use more energy – lack of food to support this – reduced fat reserves to defend from the arctic temperatures
how much of the land in the northern hemisphere is permafrost?
24%
