Extra Reading

Question 1

Key takeaway points from Steffen., W, 2018
- ‘hot house earth’ paper

Answer 1

• Once we have crossed the 2 degree ‘hothouse earth’ pathway it will be extremely difficult to employ actions for earth to return back to ‘stabilised’ earth as we will have crossed many tipping points that will amplify positive feedback loops like a ‘domino cascade’
• Even stabilised earth will likely be warmer than any other time over the last 800,000 years at least

Question 2

How much of the inorganic biomass is made through the actions of rubisco (Erb et al 2018)

Answer 2

90%
More than 90% of the inorganic carbon that is converted into biomass is fixed by the enzyme RubisCO that catalyzes the carboxylation

Question 3

Example of how woody plant encroachment is increasing (Archer et al 2017)

Answer 3

In North America, rates of encroachment vary by an order of magnitude among ecoregions (0.1–2.3 % cover year−1)

Question 4

What percentage of plants does AMF associated with (Bender et al., 2014)

Answer 4

2/3

Question 5

How fast are we undergoing climate changes? ( Mulker., 2013)

Answer 5

100x faster than ever before

Question 6

Give an example of how extreme herbivory can be (Puntilla, 2004)

Answer 6

complete defoliation of a forest forming a treeless tundra (Puntilla, 2004), this occurred in Abisko in 1955 where there was an 80-90% mortality rate of B.Pubescens due to the E.Autumnata outbreak

Question 7

How else can Eppirita Autumnata effect plants? (Ossipov et al., 2014)

Answer 7

phenolic compounds as a result of the E.Autumnata feeding can lead to reduced levels of nutritive metabolites, potentially increasing the recovery period of the B.Pubescens

Question 8

How do we know that deoxygenation was the cause of the end-permian mass extinction? (Sperling et al)

Answer 8

252 mya

1. Sedimentation patterns
   - light-coloured bioturbated sediments below the extinction horizon
   - dark coloured, unbioturbated sediments above the extinction horizon
2. Evidence of euxenic conditions form looking at iron speciation and pyrite framboid sizes
3. fossil molecules derived from the pigments of green sulfur bacteria which require anoxic conditions

Question 9

What is the main lesson from the geological oxygen record for modern global change (Sperling et al)

Answer 9

modern organisms are likely facing a much lower-magnitude perturbation but a faster rate of change, which restricts the ability of natural feedback processes to mitigate environmental stresses