Human-Induced Changes

1. Human-Induced Changes Examples • Aral Sea • Florida Everglades • Southwest Australia

2. Changes in Aral Sea http://www.dfd.dlr.de/app/land/aralsee/noaa_avhrr.html NOAA-AVHRR Image (August 1991) • Sea is split between the Republics of Kasachstan to the north and Karakalpakistan in the south • Karakalpakistan is an autonomous republic within the Republic of Usbekistan Syr-Dar’ja River Aral Sea Irrigated land Amu-Dar’ja River Caspian Sea

3. Changes in Aral Sea August 6, 1985 Space Shuttle Picture Aral Sea • A closed system, evaporation is replaced mainly by two rivers, the Syr-Dar’ja and Amu-Dar’ja • River sources are glaciers high up in the Hindu Kush and Pamir Mountains to the southeast • Increase in irrigation and diversion of the two tributary rivers has made dramatic changes • Most of this diverted water used to irrigate cotton

4. Changes in Aral Sea 1973 1987 Changes 1973-1997 • From the mid 50s until the late 80s, the supply of water dropped from 25 km3/yr to less than 5 km3/yr 1997 http://edc.usgs.gov/earthshots/slow/Aral/Aral

5. Changes in Aral Sea Changes 1988-2005 • 1988 - Note the arrow-shaped island in the Aral Sea - island is 35-km long - Deep blues and greens indicate the water- covered areas • 1996 - Intermediate image • 2005 - Island is now part of mainland • Kazakhstan government began to increase river inflow in 2003, it will be years before sea levels begin to rise http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17002

6. Changes in Aral Sea Changes 1960-1998 • Lost more than 60% of its area and approximately 80% of its volume (until 1998) • Sea level has dropped about 18 m in the same time period • Former fourth-largest lake in world is now the world's eighth-largest lake • Total collapse of the fishing industry (originally 44,000 t/a) http://svs.gsfc.nasa.gov/vis/a000000/a003100/a003112/ Evaporation of the Aral Sea using Landsat imagery from 1973, 1987, and 2000

7. Changes in Aral Sea Changes 1960-1998 • Sea's salt concentration increased from 10% to more than 23%, contributing to the devastation of a once thriving fishery • Local climate shifted to hotter, drier summers and colder, longer winters, i.e., mesoclimate changed to more of continentality • Increase of salt and dust storms • Shortening of the vegetation period • Decrease of productivity of agricultural fields http://www.dfd.dlr.de/app/land/ aralsee/chronology.html

8. Changes in Aral Sea Changes 2005-2006 • World Bank funded a dam to separate smaller, less polluted and salty northern Aral Sea from southern part • Dam completed summer of 2005 • Moderate Resolution Imaging Spectroradiometer (MODIS) images show changes - Ice both images - Channel wider - Expanded pool of shallow, sediment-clouded water - Former shorelines of the lake appear paler brown; shallower 2006 2005 http://earthobservatory.nasa.gov/Newsroom/ NewImages/images.php3?img_id=17241

9. Changes in Aral Sea Dust Storm Over South Aral Sea • MODIS image on June 13, 2006 - North Aral Sea - Lake still surrounded by its dried-up lakebed - Dust is very light in color http://earthobservatory.nasa.gov/ NaturalHazards/ shownh.php3?img_id=13648 NPR Story http://www.npr.org/templates/story/story.php?storyid=14853942

10. Changes in the Florida Everglades Historic Flow • Water from central Florida moved south to Lake Okeechobee and then south to and east to the ocean and Gulf

11. Changes in the Florida Everglades “Improving” Nature

12. Changes in the Florida Everglades Present Challenges for the Everglades • Water management - Reduction of wetlands - Many animals are specifically adapted to the alternating wet and dry seasons • Water quality - Water runoff from farms brings excess nitrates and phosphates into the park • Non-native species - Native trees, such as mangroves and cypress, are being replaced by exotic species - Numbers of wading birds nesting in colonies (rookeries) in the southern Everglades have declined 93% since the 1930s • Explosive regional population Before After http://www.nps.gov/archive/ ever/eco/threats.htm

13. Changes in the Florida Everglades Restoration Project

14. Changes in Southwest Australia Bunny Fence Southwest Australian region has been subject to considerable land use change since late 1800s, with an estimated 13 million hectares of native vegetation removed for agricultural purposes Currently a 750 km rabbit proof fence separates the croplands along the Southwest coast from native vegetation in the continental interior http://www.nsstc.uah.edu/~nair/BUFEX05/study_area.html

15. Changes in Southwest Australia Bunny Fence Due to the high contrast in albedo between the croplands and native vegetation, the boundary separating these areas is a prominent feature in the satellite images for this region Environmental impacts of land use change in this region include alteration of subsurface water storage, regional climate and local hydrology. Extensive removal of native vegetation with deep roots has lead to rising of the water table with the end result of increased salinity in surface soil and associated decrease in agricultural productivity

16. Changes in Southwest Australia Bunny Fence Rising soil salinity poses a serious threat to agricultural productivity in the future and has serious economic consequences Several studies show connections between land use change and regional climate of this region A 20% decrease in rainfall has been reported in this area following substantial clearing of native vegetation, but is not completely clear if the decrease in rainfall is linked to changes in land use

17. Changes in Southwest Australia Bunny Fence