Natural Climate Change Flashcards
What evidence indicates widespread glacial activity in past ice ages?
Features like striations, U-shaped valleys, transported rocks, large boulders, and moraines.
How do oxygen isotope variations in foraminifera shells help record glaciations?
Low 18O/16O ratios in ice caps compared to seawater indicate glacial periods, revealing changes in ice volume and temperature over time.
What is the dominant period of change for ice ages, and what pattern characterizes these changes?
Around 100,000 years, characterized by sawtooth patterns of cooling and warming.
What is the Milankovitch hypothesis?
It suggests that changes in Earth’s orbit and axial tilt affect ice volume and climate, supported by correlations in benthic 18O records.
How do Earth’s orbital changes influence climate cycles?
Variations in tilt, eccentricity, and precession of Earth’s orbit affect seasonal radiation distribution and solar insolation, driving climate cycles.
What role do CO2 and CH4 play in glacial cycles?
Changes in ice volume correlate with CO2 and CH4 variations, and positive feedback mechanisms may amplify glacial terminations.
What is the significance of millennial oscillations in glacial periods?
They show rapid transitions between extreme cold and milder intervals within decades, highlighting abrupt climate changes.
How do ice cores from Greenland and Antarctica provide insights into past climate conditions?
They contain proxies like 18O/16O ratios, calcium content, and methane, revealing detailed climate records and abrupt changes.
How does thermohaline circulation impact global climate?
It redistributes heat, impacting rainfall and climate stability, and disruptions can trigger circulation reorganizations.
What does the salt oscillator hypothesis propose?
It suggests a balance between salt buildup and export leads to oscillations, influencing climate stability.
How does understanding past abrupt climate changes help comprehend current climate perturbations?
It provides insights into potential impacts and mechanisms of climate changes due to greenhouse gas emissions.
What significant human migration event occurred between 13,000 and 12,000 years ago?
Humans migrated to the Americas via a corridor between North American ice lobes and the exposed Bering Land Bridge.
How is human hunting linked to the extinction of large Ice Age animals?
The rapid spread of humans across the Americas and dependence on large game likely contributed to the extinction of species like saber-toothed tigers and woolly mammoths.
What facilitated the transition from hunting-gathering to farming post-glaciation?
An equable climate and food control enabled the rise of ancient civilizations in Mesopotamia and Egypt.
Why didn’t farming begin during the penultimate glacial termination?
Possible factors include lack of population pressure or cultural sophistication at that time.
