geography climate change inquiry Flashcards
what are ice cores?
Ice cores are cylindrical layered ice that scientists can use to gather data on the past climate.
how do ice cores provide information on past climates?
- Bubbles become trapped in the ice, capturing the gas concentration of the then current atmosphere (temp, gg gases)
- The deeper the core, the older the ice is; as new layers form, the texture of the ice sitting at the top changes
- The thickness of each layer determines how much snow has fallen in a year, as well as other factors such as melt layers (seasonal changes)
- Wind patterns
- Volcanic activity
how is volcanic activity recorded in ice cores?
-Volcanic activity is recorded through ash and dust that comes trapped within the layers of snow.
how are wind patterns recorded in ice cores?
-Wind patterns are determined by taking ice cores from multiple locations within close proximity and seeing where past snow has drifted
how are past temperatures recorded in ice cores?
Temperatures of past climates are found through chemical testing of the trapped air in the bubbles found in ice cores, as colder temperatures lead to a higher concentration of oxygen isotope in the snow.
how are gg gases stored in ice cores?
Past greenhouse gases can be determined by investigating trapped air. When snow is compacted and turned to ice, air is trapped in bubbles, this process usually occurs 50-100m below surface
how are ice cores extracted?
There are 2 types of drills used; mechanical and thermal.
- mechanical; a rotating pipe, with cutters at the end. When the drill barrel is rotated, the sharp cutters cut a circle around the ice to be cored until the barrel is filled with said core (the length varies from 1 metre to 6). The leftover cuttings (chips) are transported to a chip chamber in the drill. The drill barrel is rotated by either physical force (hand auger), or with an electromechanical motor drive.
- thermal; In contrast, thermal drills use a ring-shaped heating element to melt a circle around the ice to be cored, the melt water is then stored in a tank within the drill.
how are ice bubbles extracted from ice cores?
bubbles are extracted via melting, crushing or grating the ice in a vacuum. Upon this physical force, the gas components within these bubbles are released and analysed.
how is the ocean an indicator for human induced climate change? (3)
-The temperature of our oceans are a great indicator of overall global warming or cooling.
The surface of the sea temperature varies to that of the deeper water, due to; evaporation, wind, sunshine and humidity.
-Salinity within the ocean acts as a measurement of climate change as areas with higher salinity levels indicate less precipitation and vice versa.
-Rising sea levels are also an indicator of climate change as melting glaciers and ice sheets lead to the rise of our waters.
how is ocean data collected?
- NASAs Moderate resolution imaging spectradiometer (MODIS) is a satellite
- argo floats which are a international collaboration of buoyant floats that collect oceanic data
describe the role of MODIS
provide surface ocean temperature data. These same satellites also have the ability to measure the height of the sea surface (via bouncing microwaves off of the oceans surface)
describe the cycles/how argo floats work?
- data is derived from battery-run, neutrally buoyant argo floats that spend their lives drifting at sea. Usually at 10-day intervals,
- the floats will pump fluid into an external bladder and rise to the surface over several hours, all whilst measuring temperature and salinity.
- The position of the floats when they surface is determined by neighbouring satellites/GPS, where the floats then transmit their data.
- The floats ‘bladder’ will then deflate causing the float to return to its original density, sinking to drift until the cycle is repeated.
- Floats are designed to make about 150 cycles.
describe the two types of argo communications
ARGO ARRAY- floats using Argos, only 200 measurements of pressure, temperature, and salinity are taken.
- 40% of the floats in the argo array, use the Système Argos location and data transmission system- meaning for measurements to be transmitted, the float must spend between 6 and 12 hrs at the surface to avoid error in the data reception.
- ARGOS USING GPS/IRIDIUM
- gps is used to track location of float, whilst iridium is used to transmit data to satellites.
- iridium is a two way communication meaning Argos path can be altered
how can we prove climate change (human induced) (3)
- By 2012, sea levels had risen 225 mm higher than in 1880. -Sea surface temperatures in the Australian region have been shown to have warmed by 0.9° C since 1900.
- Ocean heat content is measured in joules and is a key indicator for global warming, since 1971, the upper 700 metres of the ocean has increased its heat content by 17 x 1022 joules- accounting for 63% of additional energy accumulated by the climate. Below 700 metres, accounts for approximately 30% of additional energy, with the remaining 7% being emitted to the cryosphere, atmosphere and land.
how can we prove climate change (geological time)
- The most well known ice core that proves this is the Vostok ice core obtained by joint Russian, European and French scientists working at the Vostok station in Antartica- 1987
- . The team managed to drill a core that reached 3,190 metres deep, making it the longest core ever obtained, with records dating back to 800,000 years before present, the core also revealed 8 previous glacial cycles in its recordings.
