Chapter 12 - Orbital Scale Interactions and Mysteries Flashcards
What are some regional climate responses of ice sheets?
Albedo temperature feedback, disruption of wind circulation due to ice sheet height and nearby ocean cooling
How does the North American ice sheets influence ocean temperature?
GCM models have shown that the cold temperatures over the ice sheet as well as the clockwise flow of wind around the central ice work to send cold winds over the western N Atlantic ocean.
How does the North American ice sheets influence European climate?
The cold N Atlantic sea sends cold air into the west maritime parts of Europe. Precipitation is also lowered in these regions as less water vapour is given off
What would happen if the Arctic and Norwegian seas were ice covered?
The loss of the moderating ocean influence would greatly strengthen the cold winters due to high pressure Siberian cell.
What are some global climatic responses of ice sheets?
Sea levels will decrease, causing drier climates and stronger seasonal temperature extremes (particularly inland), and CO2 levels will be varied
What might account for the mismatch between insolation forcings and temp of ice sheet response?
Internal processes in the climate system, including regional and large scale ice driven responses
In what sense are ice sheets both a climatic response and a source of climatic forcing?
They are a climatic response as they result from low insolation forcing, however are also a climate forcing due to the albedo effect, sea level changes and air flow changes
Name an ice-driven response and explain its origin
One ice driven response comes from N Atlantic ocean cooling due to the N American ice sheet. This in turn sends cold AIR flow into the western maritime parts of Europe. Precipitation is also lowered in these regions as less water vapour is given off
Summarize the three explanations for the unexpected strength of the 41,000 response of ice sheets between 2.75 and 0.9 mya
Insolation varied mainly at 41,000 years, Antarctic ice fluctuations at 23,000 cancel out northern d18O, and co2 positive feedback at 41,000
How could NH ice sheets affect climate in the SH?
GCM have shown that the SH is too far for direct ice-driven responses. Instead, climate may be influenced by sea level changes, or more plausibly, co2 changes. This is consistent with the positive feedback relationship present here.
What evidence suggests orbital scale changes in NH ice volume drive changes in CO2 rather than the opposite?
The phasing between the records is so close that this argues against co2 as an ice forcing (slow ice response time). Instead, it is likely that ice decreased co2 concentrations through strengthening the carbon pump via increased solubility, enhanced fertilisation by wind blown trace elements and decreased sinking depth
