Ecosystem level impacts of CC

Question 1

Arctic warming estimates

Answer 1

Low: 4-5 degrees C
High: 12 degrees C
Over the next 50-100 years

Tundra lands are dominated by mosses and mostly organic soils. 1/5 of the worlds carbon is stored here, beyond the treelike. locked out of the atmosphere, too cold for decay.

Question 2

Evidence of vegetation shifts

Answer 2

Shift from indigenous deciduous to exotic evergreen in South Switzerland

Pic of phone of the frost days reducing and the number of exotic spp increasing

Extremes of cold getting less in magnitude and fewer in freq.

Question 3

Why does the arctic warm faster than lower latitudes

Answer 3

1. As snow and ice melt, darker land and ocean surfaces absorb more solar energy
2. More of the extra energy goes directly into warming than evaporation. Most still frozen away so no latent heat evaporation
3. The atmospheric layer that has to warm in order to warm the surface is shallower in the arctic because of the shape of the earth. Volume is less so greater capacity to warm.
4. As sea ice retreats, solar heat absorbed by the oceans is more easily transferred to the atmosphere
5. Alterations in atmospheric and oceanic circulation can increase warming. Can move a lot of energy and increase warming capacity, A lot of energy goes into Arctic through North Atlantic Drift and we dont get much out of it. But with warming, it would start giving out energy?

Already lost 10% of sea ice in the last 30 years, expected to lose 50% by the end of the century. Decrease in snow covered areas expected to be greatest in spring suggesting a further shorting of snow season and an earlier pulse of river discharge to the ocean

Question 4

Arctic vegetation zones are likely to shift

Answer 4

Tundra has a very short snow-free season bt at the same time 24hour light.

Currently: Mid-june photosynthesis starts. Drops off before august. The amount of radiation received in high and june and plants cant take advantage until no snow. So potentially max increase in drawdown. July has a potential max incr in drawdown. However, august and september could have a potential increase in carbon release

We need these two sides to balance so its not a c source.

Some are predicting a reduction in tundra as the boreal forest is already moving north. It is a dark forest and so adds to warming. Carbon won’t stay in soil in trees grow.

Changes aren’t uniform there is a reversal in some places. Might be in the big deltas where trees will never got a hold because fo shifting deposits. The tree line is moving south. in some places. Bu predominant shift north. May have to cross mountain barriers (have?)

Predicted there will be upslope movement sand northwards displacement of vegetation zones in Arctic. Altitudinal and latitudinal zones are analogous, but not identical

Question 5

Northern permafrost

Answer 5

Many soils frozen all year round –> permafrost. They contain vast amounts of C. If it warms and dries then will be decayed –> CO2

If it warms and is wet then we will get fermentation (anaerobic) and methane. 23x worse GG then Co2

These soils tend to melt –> wet. In sumer it thaws to a certain depth so ice underneath and melt surface. Then get water logging. So anaerobic bc no O2. Compare sites to when they were permafrost to what they are now. So try and predict future of them and other regions Have measured depth of thaw to be x2 4 years previous (2002)

Question 6

Changing landscape dynamics with warming

Answer 6

Mosses grow in wet, and produce peatlands to some depth then we get plants on that. This will drawdown CO2, net sink for CO2.

With melted permafrost land slumps, wetlands give off methane. Still have good drawdown but wetter areas pump out methane –> source. As much of permafrost is lost we extend extent of wetland areas then we are releasing lots of ch4

Changes in C storage and release are very patchy across the landscape. need to figure ut value but cant spot dissolved inorganic C / DOC /POC that are leaving via water and may gas out

Question 7

What did one rain event cause in a reindeer habitat in winter

Answer 7

68,000 reindeer deaths from starvation

Caribou young are exhausted by heat days. Can fall in ice and drown. They are getting richer forage though so some advantage. Can also get outbreak of mosquitos. Calves can be exsanguinated or made weaker

Voles can have their holes flooded- they die in thousands, then nothing to eat plants

Collapse of underground snow spaces inhabited by lemmings and voles can also happen

Well established populations of lemmings and voles are no longer seen as part of the arctic. Specialised predators affected. Generalist like arctic fox can switch diet

Question 8

What are the impacts of higher temps on caribou

Answer 8

Because of unpredictable weather and rapid spring melt can have;

• more extreme heat days
• sporadic freeze thaw cycles
• thinner ice
• lower water levels
• leads open earlier
• richer forage

Causing caribou:

• shift in migration routes and calving around
• change in caribou water crossing
• more drownings
• starvation
• death from overheating and exhaustion