Global Climate Change (College Board AP® Environmental Science): Flashcards

A solar maximum is the time in the sun's 11-year activity cycle when it emits the most energy and has the most sunspots.

False.

Increased sunspot activity is linked to higher average temperatures, because more sunspots mean a higher solar output.

Ice cores trap ash, air bubbles, and microbes, and the air bubbles contain CO₂ that provides information about past temperatures.

Thicker tree rings indicate favorable, warmer conditions during that year of growth.

Pollen preserved in sediment cores from peat bogs and lake beds shows which plants grew, and so the climate conditions needed for their growth.

False.

Historical sources can be subjective, so they may be inaccurate.

Lake and ocean sediments contain the remains of organisms sensitive to environmental changes, which give indirect evidence of past climates.

There is a clear positive correlation: periods with higher CO₂ concentrations correspond to warmer global temperatures.

False.

Correlation does not equal causation, but it is convincing evidence supporting the hypothesis that CO₂ emissions from human activity are driving up global temperatures.

About 90% of global CO₂ emissions come from industry and burning fossil fuels.

Sea levels rise because melting ice adds water and because warm water expands in volume, which is called thermal expansion.

Rising sea levels increase flooding and displacement of people in low-lying areas, increase beach and coastal erosion, and destroy coastal ecosystems such as coral reefs and mangrove swamps.

Mountain glaciers are an important source of water, so their retreat threatens the water supplies of millions of people.

The distribution of terrestrial biomes is primarily determined by temperature and precipitation.

Biome boundaries are shifting poleward and upward in elevation.

False.

Colder biomes such as tundra are contracting, while warmer biomes such as tropical rainforests and savannas are expanding.

In a range shift, individual species move to new areas with suitable conditions; in a biome type change, the biome itself transitions to a different type, such as tundra becoming forest.

Climate change has altered plant and tree flowering patterns and bird migration times, and has led to shorter hibernations and earlier bird nesting.

Coral bleaching is when rising ocean temperatures cause corals to expel the algae living within them, so they lose color and vitality and may die.

Warmer oceans hold less dissolved oxygen, creating dead zones where marine life cannot survive.

False.

Some effects are positive, such as more phytoplankton in some warmer seas, but these are local and limited, so overall the negative effects outweigh the positives.

Mangroves and seagrass beds are important carbon sinks, and higher CO₂ levels could help these coastal environments grow.

Marine species are migrating toward the poles to cooler water, which disrupts the ecosystems and food webs they move into.

Rising temperatures may shift the subtropical high-pressure zones poleward, which would expand arid regions and intensify tropical cyclones.

Arctic warming reduces the temperature difference between polar and equatorial regions, which may weaken the jet stream and make it more unpredictable.

Melting ice caps and glaciers increase the freshwater input into oceans, which disrupts thermohaline circulation.

Thermohaline circulation relies on heavy salt water to transport water, carbon, and heat around the globe.

The Atlantic Meridional Overturning Circulation (AMOC) is part of the ocean conveyor belt that includes the Gulf Stream, and it is slowing down as a result of climate change.

Drought slows plant growth and reduces carbon cycling and nutrient transfer to the soil, exposing it to erosion that can lead to desertification.

Overgrazing increases soil erosion because grazing animals destroy the vegetation that binds soil particles.

False.

With too much rain, crops can rot in the fields, while too little rain makes crops fail.

Coastal flooding may cause salt intrusion, which reduces the availability of water for irrigation.

Albedo is the reflectivity of a surface.

Ice and snow have a high albedo, so polar regions covered with them reflect up to 90% of solar radiation back into space.

Ice-albedo feedback is a positive feedback loop in which melting ice exposes darker ocean and land surfaces that absorb more solar energy, causing further warming and melting.

Arctic sea ice extent has decreased by about 13% per decade since 1979.

Positive feedback refers to processes that amplify changes in a system rather than stabilizing it.

Permafrost is permanently frozen ground that stores large amounts of carbon and methane.

Thawing permafrost releases methane, a potent greenhouse gas that further warms the atmosphere.

Climate response time is how quickly a system reacts to changes in climate forcings.

False.

Polar regions show a faster response time because of amplified feedbacks such as sea ice melt and permafrost thawing.

Polar bears, seals, and walruses rely on sea ice for hunting, breeding, and resting.

Polar bears must swim greater distances between ice floes, which increases energy expenditure and decreases survival rates.

False.

Less ice means less ice algae, which reduces food for krill, fish, and larger predators such as penguins and seals.

Melting glaciers and ice sheets contribute to sea level rise, which erodes coastlines, floods low-lying areas, and threatens coastal infrastructure in places such as Alaska.