Climate change impacts on ecosystems Flashcards
What is positive and negative feedback?
Positive feedback enhances or amplifies an initial change, while negative feedback stabilizes a system and prevents it from reaching extreme states.
In the climate system, a positive feedback loop accelerates temperature rise, while a negative feedback loop decelerates it.
Can you give an example of positive feedback within the Earth System?
Positive Feedback: Ice – Albedo. Ice reflects sunlight efficiently, lowering insolation absorbed by Earth, making it colder. Less ice leads to less sunlight reflection, warming the Earth further.
Warming reduces ice expansion, promoting additional warming.
Can you give an example of negative feedback within the Earth System?
Negative Feedback - Weathering. Weathering consumes carbonic acid, acting as a sink for atmospheric carbon dioxide, which cools the Earth.
Warming encourages faster weathering, removing CO2 and leading to cooling.
Describe the pattern of biome distribution with temperature and precipitation.
In cold environments, treeless tundra is found with low rainfall. Higher temperatures with little rainfall lead to grasslands and deserts. Increased temperature and rainfall support trees, boreal forests occur in cool, wetter environments, and tropical rainforests are the most productive biome.
Temperate forests occur with increasing rainfall and temperature.
According to Grime’s hump back curve, why are there low levels of plant diversity in ecosystems with very low and very high productivity?
Low productivity environments support few plants, leading to low biodiversity. In highly productive environments, vigorous species outcompete slower-growing species, resulting in low biodiversity.
Both winners and losers in species abundance have increased over time.
What are external influences on climate?
External influences are factors that affect climate but are not part of the climate system itself, such as sunspot activity or volcanic ash.
Ash from eruptions can cool temperatures, while sunspot cycles affect irradiance.
Explain the role of water vapour as a greenhouse gas.
Water vapour absorbs and re-emits energy, amplifying warming caused by other greenhouse gases.
It should be seen as a consequence of warming rather than a cause.
Describe one pro and one con for an organism to adapt to climate change using plasticity or evolution.
Plasticity allows rapid change within individuals but is limited. Evolution can lead to significant species changes but is a slow process, often too slow to keep up with climate change.
Why is climate velocity fast in flat landscapes and slow in mountainous landscapes?
Climate velocity is slow in mountainous landscapes due to short uphill distances needed to maintain climate. In flat landscapes, organisms must move longer distances latitudinally, resulting in faster climate velocity.
What are the three main mechanisms that allow plants to grow more with elevated CO2?
- Increased CO2 enhances photosynthesis. 2. Rubisco is more efficient at higher CO2 concentrations. 3. Higher CO2 allows leaves to have less open stomata, reducing water loss.
This drives greater water use efficiency.
Which terrestrial biomes will show the greatest increase in productivity in response to elevated CO2?
The most productive ecosystems, such as tropical rainforests and temperate forests, will show the greatest increases in biomass in response to elevated CO2.
What is ‘resistance’ and ‘resilience’ in ecosystem responses to climate change?
Resistance is the ability of an ecosystem to not change, while resilience is the ability to recover after being affected.
What are the top three threats to global biodiversity?
The top three threats are (1) land use change, (2) climate change, and (3) atmospheric nitrogen deposition.
The most important threat in tropical regions is land use change.
Name three factors that facilitate disturbance by humans.
Biodiversity loss is greater in areas with high human populations, near roads, and in accessible landscapes.
Describe how permafrost thaws by deepening of the active layer.
Permafrost is permanently frozen ground. The active layer thaws each summer, and as it deepens, it thaws deeper into the permafrost, which continues to freeze again each winter.
What change to vegetation results in Arctic greening?
Arctic greening is an increase in biomass or leaf area, occurring from greater growth of arctic plants and expansion of large deciduous shrubs, known as ‘shrubification.’
Describe the seeder-feeder effect that can increase N deposition in upland areas.
An orographic feeder cloud traps nitrogen in aerosols, and a seeder cloud rains above it, washing out the trapped nitrogen and adding more through its own deposition.
