Climate Variation and Change Flashcards
What are proxy indicators?
ice core data, sediments, coral reefs, ancient pollen, tree-ring…
How is the current climate monitored?
weather station data, remote sensing data, numerical modeling using General Circulation Models (GCM)
how is the future climate monitored?
numerical prediction using GCMs
What are some methods for long term climate reconstruction?
Some paleoclimatic techniques yield long-term records that span hundreds of thousands to millions of years.
Where do long term records come from?
Such long-term records come from cores drilled into ocean-bottom sediments or into the thickest ice sheets on Earth.
What is isotope analysis?
a technique that uses the atomic structure of chemical elements, specifically the relative amounts of their isotopes, to identify the chemical composition of past oceans and ice masses.
How does isotope analysis help us?
Helps us understand how much ice the temperature of earth was around /fluctuated over time.
What is oxygen isotope analysis?
So, it’s about measuring the ratio of O18 (heavy compared to O16) and O16.
Explain oxygen isotope analysis:
Because O18 is heavier, it takes longer to evaporate. Like in the subtropics we have more O16 carried (deposited near the poles and frozen), but the O18 will evaporate sooner.
When does the proportion of O18 increase? Why?
The proportion of O18 increases in ocean water during cold periods, when more O16 is locked up in glaciers and ice sheets.
Where do we see oxygen isotope analysis?
In ice cores.
What are ocean sediment cores?
Shell building organisms build their shells from stuff they find in their environment (including oxygen molecules). When they die, they float to the bottom and get buried.
True or False: We can see a change in the 18O/16O ratio in the ancient shells of long dead marine organisms, found in these sediment cores, which can be several kms long, yielding data of past conditions which span 70 million years.
True
What are some methods of short term climate reconstruction?
The tools for short-term climate analysis consist mainly of radiocarbon dating and the analysis of climate proxies (growth rings of trees, speleothems, corals, etc.)
What is an example of short-term climate reconstruction?
Dendrochronology, wide ring in good years.
What are some methods of natural climate fluctuation?
-Solar variability -Earth’s orbital cycles (Milankovitch cycles)
-Continental position and topography -Atmospheric gases and aerosols
True or False: earth’s orbit is more elliptic,
True
What is earths obliquity?
23.44°
What is Axial Precession?
Earth’s axis of rotation points at different points in the sky Impacts the timing of equinoxes and solstices relative to perihelion and aphelion
True or False: Currently perihelion occurs during NH winter, at other times it coincides with NH summer.
True
What are Milankovitch Cycles?
ilankovitch cycles describe the collective effects of changes in the Earth’s movements on its climate over thousands of years
what are some causes of present climate change?
Contributions of greenhouse gases including carbon dioxide, methane, nitrous oxide, halogenated gases, anthropogenic greenhouse gases.
What are some mechanisms for natural climate change fluctionation?
-Solar variability Earth’s orbital cycles (Milankovitch cycles)
-Continental position and topography -Atmospheric gases and aerosols
True or False: -Natural variability in solar insolation cannot explain modern temperature trends. ***
True
