In Depth Notes on Lectures 9-15

Pleistocene Megafaunal Extinctions

Extinctions that occurred around 10,000 BC coinciding with human migration to North America; megafauna lacked adaptation to human presence.

Human Role in Extinctions

Advanced hunting technologies and migration contributed to rapid decline in megafaunal populations.

example of Ecosystem Imbalance

Removal of keystone species can destabilize ecosystems, causing cascades of population declines among dependent species.

Predator-Prey Dynamics

Imbalance in populations may lead to over-predation or prey population explosions, resulting in ecological collapse. booms and crashes

Medieval Warm Period

A period in the 9th century A.D., favorable for agriculture in Europe, particularly for vineyards.

Little Ice Age

A cooler period from the 14th to 16th century AD and ends 18th to 19th century that affected temperatures and led to abandoned settlements.

Evidence for Climatic Changes

Historical records, pollen data, and sea temperature analyses indicate changes during and after the Medieval Warm Period.

Causes of Climatic Changes

Volcanic activity, solar activity changes, and greenhouse gas emissions influenced climatic changes.

IPCC Reports

Provide scientific bases for climate policy, outlining future warming scenarios and risks.

Climate System Components

Include atmospheric, land surface, ocean, and sea ice components

Nitrogen in Atmosphere

Predominantly exists as N2, making up 78% of the atmosphere.

Nitrogen Fixation

Natural processes including biological activity, human intervention, and lightning that convert N2 to reactive forms.

Reactive Nitrogen

Forms like NH4 and NO3 that cause environmental issues like eutrophication and health impacts.

Ocean Acidification

Increased CO2 leads to lower pH in oceans, negatively impacting marine ecosystems.

Impact on Marine Life

affects shell-forming organisms such as corals and pteropods.

Plastic Production

Crude oil and natural gas are primary materials for plastic production, contributing to greenhouse gas emissions.

Microplastics

Found globally, including in human tissues, affecting food chains and human health.

Degradation of Plastics impacts

Plastics release harmful additives and contribute to disease spread, impacting aquatic ecosystems.

Arctic Amplification

Rapid warming in the Arctic linked to global temperature rise and loss of sea ice. This is at twice the speed of the global average temperature increase.

Feedback Loops in Climate Models

Interactions among climate components that amplify or mitigate climate change.

Climate Forcings

External factors that change the amount of the sun’s energy that is absorbed by the Earth, or how much is trapped by the atmosphere..

Biomes and Ecosystem Pressures

Global temperature rises can lead to shifts in biomes, creating new pressures on ecosystems.

Algal Blooms

Caused by nutrient overload, depleting oxygen and intensifying ocean acidification.