Cryosphere and Building Earth's Climate Flashcards
What is the cryosphere?
The cryosphere refers to the frozen water components of Earth’s system, encompassing all the ice and snow found on the planet.
What are the components of the cryosphere?
-Polar Ice Caps
-Glaciers
-Sea Ice
-Permafrost
-Icebergs
-Ice Shelves
-Snow
Describe the distribution of ice between the hemispheres.
The northern hemisphere has less land mass so has lots of ice sheets, sea ice and permafrost.
The southern hemisphere has the Antarctic continent so has lots of ice sheets and shelves (Antarctic Ice Sheet= 60% of the world’s fresh water.)
Identify the periods of extensive glaciation in geological time.
-Wisconsin glaciation (21,000 years ago).
-Karoo/Carboniferous-Permian glaciation (300 Ma).
-Sturtian (710 Ma), Marinoan (635 Ma) and Gaskiers glaciation (582 Ma and much shorter) occurred after the break up of Rodinia.
-Huronian glaciation (Proterozoic, 2.4-2.1 Ga)
What is the evidence used for past glaciations?
-Drop stones carried by ice which have been deposited in proglacial strata.
-Ice cores (10-100s Ka)
-Ocean sediments (10-100s Ka)
-Meteorological data (100s years)
-Dendrochronology (100s years)
What are the Milankovitch cycles and over what time frame do they cycle?
-Eccentricity is the shape of the Earths orbit (100,000 Yrs)
-Obliquity is the tilt of Earth’s axis (40,000 Yrs)
-Precession is the wobble of Earth’s axis (20,000 Yrs)
Explain the issue with the Milankovitch cycle theory.
-About 1Ma glacial cycles changed from 100,000 cycles to 41,000 cycles, which is not explained by the Milankovitch cycles.
-The change in solar radiation due to Milankovitch cycles does not fully account for observed climate change.
-Some glacial cycles start 10,000 years before solar forcing kicks in.
Are ice ages typical of Earths climate?
No
What does the weathering of silicates do to atmospheric CO2 levels?
It removes CO2 from the atmosphere reducing atmospheric CO2 levels.
Silicate+CO2+H2O=Cations+HCO3+SiO2
Entering a Snowball Earth
A combination of low greenhouse gas levels (especially CO₂), albedo feedback, and orbital changes cools the planet. This cooling leads to the growth of ice sheets that expand and reinforce each other through positive feedback loops, resulting in a nearly ice-covered Earth.
Exiting a Snowball Earth
Volcanic CO₂ outgassing gradually builds up greenhouse gases in the atmosphere, causing a greenhouse effect that warms the planet. As the ice melts, the albedo effect decreases, and the ice retreat accelerates, eventually restoring a more temperate climate.
How much faster is warming in the Arctic?
Arctic amplification increases warming by 2-3 times.
What causes Arctic amplification?
-Albedo feedback
-Melting of permafrost (both direct and secondary)
-Coastal erosion
-Methane release
What are climate models?
Climate models are models used to simulate and predict how the Earth’s climate system works and how it may evolve under various scenarios. Climate models work by representing the interactions between various components of the Earth system (atmosphere, oceans, land, and ice) and simulating how these systems respond to changes in forcing factors (e.g., changes in CO₂ levels or solar radiation).
What are the required inputs of climate models?
-Initial conditions (atmos/ocean at t=0)
-Boundary conditions (e.g. land)
-external forcings (e.g. solar radiation)
-Settings in model not predicted (GHGs)
What are the simulated outputs of climate models?
-Atmos/ocean dynamic quantities (wind, currents, temp and pressure)
-Sea-ice distribution and thickness
Describe what the geological record tells us about present and future climate.
The geological record serves as a time machine, offering a glimpse into past climates and the processes that shaped them. By examining the evidence of past climate fluctuations, warm periods, cooling events, and mass extinctions, scientists can gain valuable insights into the natural forces driving climate change and how the Earth system might respond to future changes. The geological record shows us that the current rate of climate change is unprecedented in human history, but it also highlights the potential for significant shifts in climate and ecosystems in response to rising greenhouse gas concentrations.
Be able to discuss how to use climate models for research.
Using climate models for research is an essential method for understanding how the climate system works, predicting future changes, assessing the impacts of climate change, and evaluating the effectiveness of mitigation and adaptation strategies. Climate models provide invaluable insights into the dynamics of climate systems, the role of human activity in driving climate change, and the potential consequences of different emissions scenarios. By simulating a range of conditions and scenarios, researchers can help inform policy decisions, guide mitigation efforts, and prepare society for the impacts of a changing climate.
