Shifting baselines and tipping points

Question 1

Define baseline data

Answer 1

set of information against which to compare subsequent data

Question 2

Define shifting baselines

Answer 2

Refers to the idea that each generation perceives the environment they grew up in as “normal,” even if it has already changed from previous generations.

Question 3

How do shifting baselines relate to generational change?

Answer 3

Each generation accepts a degraded state as the baseline for comparison.

Question 4

Are shifting baselines an example of a positive or negative feedback loop?

Answer 4

Positive

Question 5

Define tipping point

Answer 5

A critical threshold in an ecosystem or climate system. Once point is crossed, can lead to irreversible or dramatic changes which can be impossible or difficult to reverse.

Question 6

What is the climate tipping point?

Answer 6

point at which global climate so changed by human actions that it can no longer properly function

Question 7

When was the ‘Great Dying’ (worst mass extinction event on record)

Answer 7

250 million years ago

Question 8

What did the Great Dying event show?

Answer 8

mass extinction, but showed nature eventually able to recover over millions of years

Question 9

The event that causes a shift into disequilibrium is the…

Answer 9

tipping point

Question 10

Do scientists agree whether loss of biodiversity can result in ecosystem collapse

Answer 10

No
- Some argue species decline + extinction= natural processes (proved by events like the Great Dying which demonstrate resilience of ecosystems)
- Others argue there is a tipping point at which so much biodiversity is lost that system inevitably collapses

Question 11

3 signs/evidence that can indicate an ecosystem has reached tipping point

Answer 11

1. Sudden loss of species
2. Major changes in vegetation (rainforest > savanna)
3. Rapid climate change (increased floods)

Question 12

At what degrees of global warming will multiple negative tipping points occur

Answer 12

2 degrees

Question 13

What tipping points will occur if global warming reaches 2 degrees

Answer 13

• Melting ice sheets
• Ocean circulation affected- changing weather patterns
• Melting permafrost- unleash contaminants into water, trigger greenhouse gas emissions

Question 14

How would melting permafrost impact global warming

Answer 14

permafrost holds 2.5 times the carbon that is currently in the atmosphere. Once released, a cycle ensues of warming soil, increasing heat-trapping gasses into the atmosphere, and raising global temperatures.

Question 15

What are 4 types of evidence relating to tipping points

Answer 15

1. Paleoclimate (natural records- tree rings, ice cores)
2. Observations (satellites, weather stations)
3. Theory (feedback loops- show how small changes can lead to large effects)
4. Computer modelling (simulations)

Question 16

What is evidence of tipping points in the cryosphere

Answer 16

Greenland and Antarctic ice sheets melting (tipping point= irreversible melting beyond 1.5-2 degrees warming. Once certain amount of ice lost, positive feedback loop formed as reduced reflectivity (albedo) causes more heat absorption and fast melt)

Question 17

Evidence of tipping points in biosphere?

Answer 17

Amazon Forest Dieback
- Deforestation and longer dry seasons reducing rainfall and tree survival. Could turn rainforest into dry savanna if too much forest lost

Question 18

Evidence of tipping point in hydosphere?

Answer 18

Slowing of the global conveyor belt ocean current- collapse of this circulation would disrupt weather patterns.