Tipping points, resilience and models

2 subtopics

What are tipping points

The minimum amount of disturbance needed upon an ecosytem to trigger significant change or transition into a different state, often leading to irreversibility in ecosystem function.

what are knock-off- effects defined as?

Consequences that arise from a change in one part of a system, affecting other interconnected elements and potentially leading to further changes.

what causes a tipping point?

positive feedback loops.can push an ecological system towards and past its tipping point, at which point a new equilibrium is likely to be reached

why can tipping points be difficult to predict?

• Delays in feedback loops, complicating system modeling.

• Non-synchronous changes across system components.

• Difficulty in identification until after being passed.

• Global interconnectedness, where distant activities (e.g., fossil fuels burning) can lead

What are some severe consequences of environmental tipping points on the immediate environment?

They can be severe and long-lasting, extending beyond the immediate environment, such as the melting of polar ice caps and glaciers.

How does the melting of polar ice caps and glaciers contribute to rising sea levels?

The water released from melting ice adds to the ocean's volume, causing sea levels to rise, which can inundate low-lying areas, cause flooding, erosion, and damage infrastructure.

What impact do melting polar ice caps and glaciers have on ocean currents?

They alter the salinity and temperature of the ocean, affecting ocean currents, which can impact global weather patterns and have cascading effects on ecosystems.

How does the melting of polar ice caps and glaciers affect biodiversity?

It leads to the loss of habitat and food sources for species adapted to polar regions, resulting in declines in biodiversity.

What greenhouse gases are released by melting permafrost and what is their impact?

Melting permafrost releases large amounts of methane and carbon dioxide, both potent greenhouse gases, contributing to climate change and further melting of ice.

How do melting polar ice caps and glaciers influence global temperatures?

They change the reflective properties of the Earth's surface

What is meant by the 'resilience' of a system?

Resilience refers to a system’s ability to maintain stability and avoid tipping points by absorbing disturbances and reorganizing while undergoing change.

What factors contribute to a system's resilience?

Diversity and the size of storages within systems. Systems with higher diversity and larger storage are less likely to reach tipping points.

How does diversity contribute to a system's resilience?

High diversity provides multiple ways for animals and plants to respond to change, maintaining ecosystem stability (e.g., complex food webs in rainforests).

How do storage sizes contribute to a system's resilience?

Larger storages (e.g., long-lived trees, large lakes) help systems absorb changes with less immediate impact, providing a buffer against rapid shifts. Smaller storages (e.g., ponds) are more quickly affected.

How do human activities affect the resilience of natural systems?

Humans can reduce resilience by decreasing diversity (e.g., hunting species to extinction, deforestation) and diminishing the size of natural storages (e.g., converting grasslands to monoculture crops).

What is an example of an ecological system with high resilience?

Mangrove forests, found in tropical and subtropical coastal regions.

Why are mangrove forests considered highly resilient?

1. Adaptability: Evolved to survive harsh coastal conditions, including saltwater and able to withstand storm surges. 2. Self-regeneration: Produce propagules that sprout into new trees, allowing quick recovery from disturbances. 3. Biodiversity: Support many adapted species, buffering against disturbances. 4. Nutrient cycling: Efficiently cycle nutrients, maintaining soil fertility and plant growth.

What is an example of an ecological system with low resilience?

Coral reefs, particularly vulnerable to human activities and climate change.

Why do coral reefs have low resilience?

1. Multiple simultaneous stressors: Threatened by overfishing, pollution, and coastal development. 2. Rising sea temperatures: Vulnerable to climate change, leading to coral bleaching and mass mortality. 3. Slow recovery rate: Corals grow slowly, making recovery from damage difficult; continued disturbances can lead to irrecoverable tipping points.

How does the unique reproductive strategy of mangroves contribute to their resilience?

Mangroves produce propagules (live offspring) that can sprout into new trees, enabling rapid self-regeneration after disturbances like storms.

What specific environmental factors make coral reefs highly susceptible to coral bleaching, indicative of low resilience?

Rising ocean temperatures and increased ocean acidity (due to climate change) are primary factors that cause coral bleaching, leading to mass coral mortality and reef degradation.

In the context of resilience, what makes monoculture agricultural systems similar to coral reefs in their vulnerability to disturbances?

Both systems possess low diversity; monocultures lack varied responses to pests/diseases, similar to how coral reefs' specific adaptations make them fragile to multiple stressors like warming oceans.

Why is the slow recovery rate of coral reefs a significant indicator of their low resilience to environmental disturbances?

Corals grow slowly, making it difficult for reefs to recover from damage. Prolonged or repeated disturbances can push them past a tipping point from which they cannot recuperate.

How do rainforests demonstrate high resilience through their storages?

Rainforests contain large storages of long-lived tree species and high numbers of dormant seeds, which promote a steady-state equilibrium despite disturbances.

Why are artificial agricultural crop systems considered to have low resilience?

They are monocultures with low diversity, meaning a disturbance (e.g., new pest or disease) cannot be easily counteracted, making them highly vulnerable.

Contrast the resilience of natural grasslands versus agricultural grasslands.

Natural grasslands have high resilience due to diverse species and underground storages (seeds, nutrients, roots) for quick recovery after disturbance. Agricultural grasslands, being monocultures, lack this diversity and storage, resulting in low resilience to disturbances like fire.

What is coral bleaching and what are its primary causes?

Coral bleaching is when corals expel symbiotic algae, turning white. It is primarily caused by rising ocean temperatures and increased ocean acidity due to climate change.

What is a model?

A model is a simplified version of reality used to represent a system, analyze its workings, and predict its responses to change.

What are the main strengths of using models in scientific study?

1. Models simplify complex systems

2. allow predictions about system reactions

3. enable observation of effects from changed inputs without real-life events

4. facilitate communication of potential environmental issues.

What are the key limitations of models?

1. Models can be oversimplified and inaccurate; their results depend on data quality

2. predictions become uncertain over time

3. different models can yield vastly different output

4.  it's impossible to incorporate all interacting factors of complex environmental systems.