21-3 Flashcards
what are pueblos and how did ancient pueblos get abandoned?
pueblos were Native American “apartment homes” made of stone and sunbaked clay with rooms of worship. evidence from tree rings indicate periods of intense drought which broke down society.
what are ice ages?
glacial episodes during cold periods, ocean levels lower, glaciers over large portions of Earth’s surface
what are the possible explanations of why climates change?
plate tectonics, earth’s orbital motion, ocean circulation, solar activity, and volcanic eruptions.
how are plate tectonics an explanation for climate change?
Pangaea broke apart, shifting continents (specifically underwater tectonic plates) created affect of climate
Oceans grow and shrink, changing circulation patterns of ocean water which moderates climate because it moderates the air above them
how does mountain building relate to carbon dioxide?
it accelerates weathering and erosion, which removes carbon dioxide from the atmosphere, reducing past high CO₂ levels.
how is earth’s orbital motion an explanation for climate change?
Earth revolves around the sun in an oval or elliptical like path
Change in shape brings the Earth closer to the sun, may trigger the next ice age
Angle at which Earth’s axis tilt over time changes
what happens to seasons when tilt is at its maximum and minimum?
when tilt is at its maximum - more solar absorption occurs/greatest seasonal change; when tilt is at its minimum - less solar absorption/least seasonal change
how is ocean circulation an explanation for climate change?
El Niño changed ocean circulation causing short term climate fluctuations. Some areas that are normally arid receives a lot of rain during El Niño, wet areas may become dryer
how is solar activity an explanation for climate change?
sun has been giving off increasing amount of energy over its lifetime. Short term solar radiation fluctuations can change global climates
what are sunspots and how do they change Earth’s temperature?
sun spots: dark, cooler regions on the surface of the sun; more sunspots correspond with warm periods
how are volcanic eruptions an explanation for climate change in the short term and in the long term?
volcanic eruptions release lots of gases and ash into the atmosphere.
Gases and ash reflects solar radiation to space which may lower temps in the short term. On the long term it may warm up the atmosphere because CO2 is added to the atmosphere (greenhouse gas that holds heat in).
what is the greenhouse effect?
in a greenhouse the plants and soil absorbs sunlight energy, cannot escape out, so greenhouse gets hotter.
what causes Earth’s atmosphere to warm?
Much of Earth’s heat radiation is reflected back by the atmosphere, warming the planet
what are the greenhouse gases? what happens if there’s not enough and too much?
carbon dioxide, water vapor, methane. If not enough - too thin and cold, if too much - too thick and hot
How do scientists know CO₂ levels were stable until the late 1800s?
Confirm this by measuring air bubbles in Antarctic ice cores. We can compare today’s air bubbles with the air bubbles from then and compare the carbon levels in the ice cores. If CO₂ had escaped, past levels would appear lower, confirming they remained constant.
What do most scientists believe is causing the rise in CO₂ levels?
Human activities like burning wood, coal, oil, and natural gas.
What is global climate change?
increased atmospheric temperatures and climate changes caused by rising temperatures.
What is another hypothesis for global warming?
Some believe changes in the sun’s energy output may cause natural climate variations, leading to warmer and cooler periods.
what are climate changes?
result of changes in CO2 and amount of solar energy
what are climate models?
complex computer models that processes huge amounts of data on temperature, precipitation, and others; an approximation
What are the effects of Earth warming on the environment?
causes polar ice caps to melt, raising sea levels and causing floods. More heat increases evaporation, adding water vapor to the atmosphere.
How do CO₂ and greenhouse gases impact global warming?
amplify warming, while melted ice absorbs more heat, intensifying storms, heatwaves, droughts, and wildfires.
what is a nuclear winter?
a severe global cooling effect from firestorms after a large nuclear war. Soot in the stratosphere blocks sunlight, cooling Earth by 1°C, causing some crop failure and famine.
