Page 208 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

THEhumanDENOMINATOR 6 Global Circulation
ATMOSPHERIC AND OCEANIC CIRCULATION HUMANS
• Wind and pressure contribute to Earth’s general atmospheric circulation, which drives weather systems and spreads natural and anthropogenic pollution across the globe.
• Natural oscillations in global circulation, such as ENSO, affect global weather. • Ocean currents carry human debris and non-native species into remote areas and spread oil spills across the globe.
In June 2012, a dock washed ashore in Oregon, 15 months after a tsunami swept it out to sea from Misawa, Japan. The dock travelled about 7280 km on ocean currents
across the Pacific. [Rick Bowmer, Associated Press.]
This NASA Blue Marble image shows land surface topography and bathymetry (depth of the ocean floor). [Blue Marble–Next Generation, NASA, 2004.]
6d
Windsurfers enjoy the effects of the mistral winds off the coast of southern France. These cold, dry winds driven by pressure gradients blow southward across Europe through the Rhône River valley. [Gardel Bertrand/Hemis/Alamy.]
ISSUES FOR THE 21ST CENTURY
HUMANS ATMOSPHERIC AND OCEANIC CIRCULATION
• Climate change may be altering patterns of atmospheric circulation, especially in relation to Arctic sea-ice melting and the jet stream, as well as possible intensification of subtropical high-pressure cells.
• Air pollution in Asia affects monsoonal wind flow; weaker flow could reduce rainfall and affect water availability.
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6b
Scientists think that melting
sea ice in the Arctic owing
to climate change is altering
the temperature and pressure balance between polar and midlatitude regions. This weakens the jet stream
(which steers weather systems from west to east around the globe), creating large meanders that bring colder conditions to the United States and Europe, and high-pressure conditions over Greenland. [After C.H. Greene and B.C. Monger (2012), Rip current: An arctic wild card in the weather, Oceanography 25(2):7-9.]
High Pressure
Jet stream
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In August 2010, monsoon rainfall caused flooding in Pakistan that affected 20 million people and led to over 2000 fatalities. The rains came from an unusually strong monsoonal flow, worsened by La Niña conditions. See Chapter 14 for satellite images of the Indus River during this event.
[Andrees Latif/Reuters.]
• Wind energy is a renewable resource that is expanding in use.
• Ongoing climate change may affect ocean currents, including the thermohaline circulation, as well as natural oscillations in circulation, such as the AO and the PDO.
geosystemsconnection
With this chapter, you have completed the inputs–actions–outputs pathway through ParT i, “The energy–atmosphere System.” in the process, you examined the many ways these earth systems affect our lives and the many ways human society is impacting these systems. From this foundation, we now move on to ParT ii, “The Water, Weather, and Climate Systems.” Water and ice cover 71% of earth’s surface by area, making earth the water planet. This water is driven by earth–atmosphere energy systems to produce weather, water resources, and climate.
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