Climate Change Flashcards
List the layers (from Earth’s Surface of the atmosphere:
- Troposhere (clouds).
- Stratosphere (ozone).
- Mesosphere (meteors burn up).
- Thermosphere (satellites).
What is climate?
defined as “average weather” over a period ranging from months to thousands of years. Classical period is 30 years
What are the most abundant gases in the atmosphere?
Nitrogen (78%)
Oxygen (21%)
Air (1%, contains CO2)
What is a Watt?
unit of power or energy per unit time (Joule/second)
How does the atmosphere move?
Air flows from high pressure to low pressure.
How does atmospheric pressure work?
- Cool dry air sinks (higher surface pressure).
- Warm, moist air rises (lower surface pressure).
Explain the Coriolis Effect
- Earth’s rotation deflect path of moving objects (air and water).
- Deflects to the right in Northern Hemisphere
- Deflects to the left in southern hemisphere
- Greatest effect on objects that move long distances across latitudes
The process by which air and heat move is called?
Convection
Why is the 3 cell model not perfect?
Circulation is more complex due to:
- seasonal changes
- distribution of continents and ocean
Surface salinity varies by:
latitude
What are the processes affecting salinity?
Decreasing salinity (add water to ocean):
- melting ice
- precipitation
Increasing salinity (remove water from ocean):
- sea ice formation
- evaporation
What are the types of ocean currents?
Deep currents (driven by differences in temperature and salinity)
Surface currents (wind driven and primarily horizontal motion)
What is the thermohaline circulation?
Important deep current that transfers heat from tropics to poles in the North Atlantic Deep Water (NADW).
As much as 90% of ocean water.
Explain surface currents.
Involve only 10% of ocean volume.
Major impact on both weather and climate.
Due to effects of wind and Coriolis effect.
Explain Ekman transport.
Sea currents move at an angle to the wind (deflected due to Coriolis Effect).
90 degrees right of wind in N hemisphere.
90 degrees to left in S hemisphere.
What is happening at ICTZ with Ekman transport.
Water is diverging while wind is converging.
Where does the greatest intensity of solar radiation come from?
The ultraviolet, visible, and infrared parts of the electromagnetic spectrum.
What is radiative forcing?
Measures how much energy enters and leaves the Earth’s atmosphere, and how human activities have changed this balance.
Positive forcing = warming
Negative forcing = cooling
What are some GHGs?
Water, Carbon Dioxide, Methane, Ozone, Nitrous Oxide
GHGs can absorb infrared radiation and re-emit IR radiation.
What is Global Warming Potential (GWP)?
Different gases have different warming abilities.
CO2 is reference gas.
Methane 25x warming effect
Nitrous oxide 300x warming effect
What are some sources of radiative forcing?
- Solar forcing (small but +ve)
- GHG forcing (+ve forcing)
- Albedo and clouds (negative forcing, albedo is how strongly sunlight is reflected by earths surface and atmosphere).
- Human land use change (-ve forcing).
- Aerosols (negative forcing)
Black carbon/ organic soot (+ve forcing).
Name some reservoirs of Carbon.
- Gases in atmosphere (Carbon dioxide and methane).
- Organic material in plants and animals (biosphere).
- Rocks (lithosphere)
-Carbon dioxide in oceans (hydrosphere).
What is the carbon cycle?
Biogeochemical cycle
Unites all components (lithosphere, hydrosphere, biosphere, and atmosphere).
C is stored in different reservoirs and exchanged between them.
C enters and leaves at different rates (remains in reservoirs temporarily).
What is the difference between hypotheses, theories, and laws?
Law - general statement about the expectation that certain events will occur where certain conditions are met.
Hypothesis - human mental construct that provides a preliminary causal explanation of a set of facts
Theory - more mature, more complex, and more wide-ranging human mental construct.
What is the difference when a theory or hypothesis is accepted or rejected?
A theory or hypothesis that is repeatedly confirmed is provisionally accepted.
A theory or hypothesis that is overwhelmingly invalidated is rejected (falsifiability).
Explain the ozone hole mystery.
Chlorofluorocarbons were used in a variety of items that humans use. When it was discovered they were depleting ozone their use was banned and ozone began to heal itself.
What is the IPCC?
Intergovernmental Panel on Climate Change.
Review and assess most recent information produced worldwide relevant to understanding climate change.
Released 6 reports since established.
What is an atom?
Smallest identifiable unit of an element.
Atom has a nucleus (protons and neutrons) surrounded by electrons.
What is the difference between atomic number and mass number?
Atomic number = number of protons.
Mass number = number of protons + neutrons
What is an isotope?
An atom with the SAME ATOMIC NUMBER but different MASS NUMBER.
What are important characteristics of stable isotopes?
Small differences in the physical properties of each isotope affects how they are “partitioned” in the climate system.
Ex. plants preferentially take up CO2 with C12 over CO2 with C13.
What are radioactive isotopes?
Unstable that break down due to radioactive decay to produce smaller “daughter atoms”.
What is half life?
The time it takes for half of the initial parent atom to decay.
What are some radioactive isotopes?
C14 - HL of 5736 years
U234 - HL of 245,500 years
U238 HL of 4.47 billion years.
What is the keeling curve?
Shows rising atmospheric carbon dioxide over time.
Explain the Human Fingerprint of 12C and 13C ratio.
Plants prefer 12C to 13C (13C is lower in plants than atmosphere).
Oil, gas, and coal are plant-based fuels that also have low 12C to 13C ratio.
When they are burned more 12C enters atmosphere lowering the 13C to 12C ratio.
Used in evidence that burning fossil fuels are the cause of higher CO2 in atmosphere.
How do we measure temperature?
Land surface temperatures:
- ground thermometers are most accurate.
- thousands of weather stations around globe.
Ocean Air and Sea Surface Temp (SSTs):
- coastal stations, ships, Argo (floating thermometer).
Satellites (since 1970s).
Air Balloons
How long do we have historical temperature data?
Central England - 1659
Reliable regional data - 1850s
Global - 1970s
What is a temperature anomaly?
Difference between temperature of an area and the average for a selected baseline period.
What is a baseline period (temperature)?
Covers a long period of time (usually > 15 years, preferably > 30 years).
Why use temperature anomalies?
Accurately describe climate variability over large areas.
Allow for comparisons between locations and accurate calculations of temperature trends.
What is El Nino - Southern Oscillation
One of the world’s most important climate cycles.
Result from quasi-periodical changes in ocean temperature that affect tropical Pacific.
Result in a disruption of Walker Cell.
Temperatures generally increase.
El Nina - temperatures generally decrease.
How does climate reconstruction occur?
Past climates can be reconstructed from physical characteristics of the past (proxies).
What is a climate proxy?
A natural archive of the climate.
“Record” information about climate at time of their formation.
Biological, geophysical, and chemical.
What is dendroclimatology?
Measuring tree growth rates that are associated with climactic fluctuations.
Width of ring and density of wood are very sensitive to local climate.
What are ice cores?
Most informative of all paleoclimatic reconstructions (greenland, antarctica).
Snow accumulates and forms ice, deeper ice = older snow.
As far back as 1.2 million years.
What are some things measured with ice cores?
Amount of snow from thickness of layers.
Drought conditions from occurrence of ash and dust.
CO2 concentrations from trapped air bubbles.
Temperature from O2 and H isotopes.
How do water isotopes differ in rates of evaporation and condensation?
Light water (16O) evaporated more than heavy (18O) water.
Heavy (18O) water condenses or precipitates more readily than light (16O) water.
What are the two types of sediments?
Mineral and biological sediments?
What are mineral sediments?
Delivered by rivers, wind, ice, and ocean currents.
Gives information about source region and atmospheric/ ocean circulation.
What are biological sediments?
Microfossils with hard calcium carbonate (CaCO3) skeletons:
- forminifera
- coccolithophores
Microfossils with silicate (SiO2) skeletons:
- Diatoms
What is palynology?
Pollen analysis.
Distinct morphology allow for identification.
What are some other sources of paleoclimatic information?
Corals (coral banding) similar to tree rings. 100s of years
Stalagmites and Stalactites similar to ice cores. 1000s of years.
What is the difference between resolution and timespan?
Resolution refers to the small discrete quantity of time for which info can be extracted from a climate proxy.
Timespan refers to the total amount of time that a climate proxy can give us info about.
What are the main climate signals?
A - Atmospheric composition
D - Drought
P - Precipitation
E - Events (volcanic eruptions)
T - Temperature
What are Milankovitch Cycles?
Orbital cycles interact to control the amount of solar radiation reaching the atmosphere.
Determines how Earth’s climate shifts between glacial and interglacial phases.
Accurate in terms of timing but not in terms of magnitude of interglacial periods.
What is climate feedback?
A process in which it can either amplify or diminish the effects of an initial warming.
Further warming = positive feedback
Cooling = negative feedback.
What is the Younger Dryas (Big Freeze).
Global warming caused by orbital cycles.
Melting of ice and dilution of N. Atlantic water.
Slows down Thermohaline circulation and results in rapid cooling of N. hemisphere.
Why are Climate models improving.
Technology improves.
With time our knowledge of climate processes increases.
Why do we need so many climate models?
Limits due to computer speed.
Modelers make trade-offs
We are looking for “robustness” of projections.
