APES 9

9.5: GLOBAL CLIMATE CHANGE

Why there are historical changes in climate: variations in earth's orbit around the sun, specifically obliquity and eccentricity

Obliquity: how much the earth tilts, exposing northern latitudes to higher insolation at different times

Eccentricity: how far earth is from the sun

What do historical changes in climate emphasize: milankovitch cycles

The 3 main pieces of evidence to measure and estimate earth's historical temperature and CO2 levels: foraminifera shells in ocean sediments, air bubbles in ice cores, and 16O is 18O isotope concentrations in ancient ice

How do foraminifera shells help predict temperature levels at different times: ocean sediment layers with these shells have varying ages to determine which species were present, and those species temperature preference emphasizes the estimated temperatures of earth

How do air bubbles in ice cores help predict temperature levels at different times: the air from the bubbles can be tested to determine CO2 levels

How do O18 levels in ancient ice help predict temperature levels at different times: higher O18 levels mean higher temperatures

Relationship between temperature and CO2 levels: they are both correlated and increase together

Effects of climate change: rising temperature and sea level, and melting of permafrost

Effects of rising temperatures from climate change: habitat/species loss, drought, soil desiccation, heat waves, increased precipitation in some regions

Effect of melting of permafrost from climate change: permanently frozen tundra soils begin to thaw and release methane and CO2 from anaerobic decomposition

Impact of climate change towards coastal communities: property loss and potential relocation of people who can't build up and loss of barrier islands

Barrier islands: islands that buffer coastal communities and ecosystems from wind and waves

Why don't seawalls or other barriers to sea level rise help: they delay eventual flooding

Impact Of climate change on atmospheric currents: widening and weakening of Hadley cell and weakened, destabilized jet stream

How is the Hadley cell weakened from climate change: as temperature difference between the equator and poles decreases, the air ascending and expanding from the equator travels further before sinking, which shifts subtropics toward the poles and cause regions between 30-60° to experience drier climate

How is the jet stream weakened from climate change: as the arctic warms faster than other areas of earth, temperature difference between equator and poles weakens, causing wavy jet stream and extreme cold spells in east US and dry spells in western US

Impact of climate change on marine ecosystems: altered range of marine ecosystems with new habitats formed by rising sea level, photic zone shifting up from areas of ocean becoming too deep, and altered ranges for organisms as they migrate to colder waters

Impact of climate change on ocean circulation: thermohaline circulation slowing down or stopping

How is the thermohaline circulation weakened by climate change: ice melt drives the spread of fresh cold water in the north Atlantic, slowing warmer waters due to freshwater's low density making it float and not sink

How does unequal global warming occur from climate change: polar regions of earth warm faster (polar amplification), especially the north pole because there is more land and less water to absorb heat

How does melting ice cause more ice to melt in a positive feedback loop: more water is exposed to sunlight, meaning more heat is absorbed, and then temperatures rise to melt more ice

How does air pollution drive unequal global warming: atmospheric circulation distributes pollutants to the poles, and the pollutants darken the ice to lower their albedo

Impact of climate change on polar ecosystems: habitat loss, seals lose a place to rest and breath, algae doesn’t grow on ice and ruins the food web, and polar bears lose a place to hunt seals