Geol 1030 The Atmosphere, Oceans & Climate Exam II (Dr. Larsen) Open-ended
What is permafrost? Where and why does it occur?
Permafrost is permanently frozen ground is defined simply in terms of temperature, it occurs in regions where the MAT is below freezing
What is the key human perturbation to the Carbon Cycle, and why does the concern scientist so much?
We have accelerated the OC weathering and oxidation flux from sedimentary rocks from a tectonic scale to a biological scale. converted a 200 Myr process to a decade-scale process
What are the two primary ways sea ice affects climate? What are the current trends observed in Arctic sea ice and what are the implications for future climate change?
ice production in the North Atlantic and around antarctica that contributes to the formation of North Atlantic Deep water (effects the thermohaline circulation) ice-albedo feedback
Why is methane thought to have been an important greenhouse gas during the Archean Era?
-methanogens are thought to have been among the first forms of life on earth = significant biogen flux of CH4 in atmosphere -paleosol data place an upper limit of CO2 concentrations that is too low to allow for liquid surface water given a strict CO2H2O greenhouse
What caused the Earth's climate to start cooling about 30 million years ago, and how?
India started colliding with Asia around 40 m.y. ago, producing the Himalayas and the Tibetan Plateau. Himalayas provided fresh, readily erodible surfaces for silicate weathering to speed up. Tibetan plateau created the Asian Monsoon, so the water needed for weathering was available
What were two key lines of evidence that supported the idea of Continental drift and ultimately leasd to our understanding of Plate Tectonics?
Mid ocean ridges (MOR): occur throughout the oceans, mostly in centers, longest continuous mountain chain on earth "rift" in center of these ridges normal vs. reversed magnetic stripes on ocean floor these strips were mirror images on either side of MOR, getting older as you move away
Describe the Faint Young Sun Paradox, and how Earth was warm enough to have liquid water.
earlier sun was 30% less bright, so earth should have been cooler. -geothermal sources-insufficient -decreased albedo-insufficient -more greenhouse gases-must have been more CO2 and CH4 in the atmosphere
Why might melting permafrost be important for future climate change?
melting permafrost results in lakes and water logged soil which is anaerobic conditions that create am environment in which methane producing organisms can flourish. melting permafrost releases stored carbon to atmosphere, but also provides habitat for plants to grow and sequester carbon
Briefly explain the three orbital parameters that have influwnced climate during the glacial/interglacial variations of the past ~2 million years
precession (20 kyr) obliquity (41 kyr) eccentricity (100 kyr)
The carbonate-silicate geochemical cycle controls atmospheric CO2 in large art through the following equation. Explain how this equation relates to the probable initiation of "snowball Earht" episodes, and also how Earth likely recovered from such episodes? CaSiO3 + CO2 = CaCO3 + SiO2
the net result of silicate weathering on land and carbonate precipitation in the ocean is a conversion of atmosperic CO2 to solid CaCO3. This process reduces the atmospheric CO2 reservoir. During the onset of snowball earth episodes, silicate weathering would be intense b/c all land mass at the equator, and this would draw down CO2 so far that global glaciation could occur. At that point, silicate weathering would have ceased and eventually volcanic CO2 would build up enough to increase GHG effect enough to melt the ice, which would take ten million years. The super greenhouse after that would overshoot and rev up silicate weathering to very high levels, ultimately finding a new steady state.