Challenger Center: Earth Science Challenge: Lesson 3

LESSON OVERVIEW

How do images from space taken over time show us change on the Earth?

Photographs take from the windows of the ISS and images taken from Earth orbiting satellites allows scientists to compare places around the world from the past to the present. From their analyses of changes seen over time, predictions about the future can be made.

Astronauts have taken over 700,000 images of the Earth from space. These can bee seen at The Gateway to Astronaut Photography website located at http://eol.jsc.nasa.gov/.
Satellite images of the Earth taken over the past several decades and presented by topic and theme can be found at NASA’s Earth Observatory located at http://earthobservatory.nasa.gov/ .
A list of Astronaut Images found at Earth Observatory that have helped scientists understand our planet can be found at
http://eol.jsc.nasa.gov/Coll/EarthObservatory/PostedSort.htm.

Typical view out the window of the ISS of the ocean

What kinds of changes have we seen?

The disappearing snowcap of Mount Kilimanjaro,
from space.

Some areas of the world show significant change over time to due to both human impact and natural events. Humans have expanded their presence across the globe, cities have grown larger, forests have been cut down and dams have been built creating new lakes. Natural events such as earthquakes and volcanoes have changed the face of the planet. Climate changes have melted mountain glaciers causing their recession, and reduced ice levels at the polar caps.

The NASA Global Climate Change: NASA's Eyes on the Earth website, located at http://climate.jpl.nasa.gov has information about scientists’ analyses of change over time on our planet. The Climate Time Machine shows the shrinking of Arctic sea ice, the effects of rising sea levels, the change in land temperature since 1885 and carbon emissions by country since 1980.

1979 Arctic sea ice minimum
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2007 Arctic sea ice minimum
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See http://climate.jpl.nasa.gov/ClimateTimeMachine/climateTimeMachine.cfm

Clear Cutting of the Forests in Amazon

In 1992, about 25 percent of the Mato Grosso Amazon region had been clear-cut for pastures and farms. Less than two decades later, more than 80 percent of the rainforest had been cut down. Figures released by Brazil's National Institute of Space Research, which uses satellite observations to monitor the country's rainforest, show that since 1988, when 21,000 square kilometers of rainforest were cleared, the average deforestation rate has been about 19,000 square kilometers per year.

In 2006, the Brazilian government announced that the annual rate of deforestation in the country had dramatically declined. But, earlier this year, it reported an unprecedented sharp rise in forest destruction, naming Mato Grosso as one of the regions hardest hit.

Mato Grosso, Brazil – 1992
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Mato Grosso, Brazil – 2006
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Human Cities Seen From Space

Astronaut Don Pettit has assembled a sequence of several of the most striking images of city lights at night into an animated “world tour” of cities at night. This video, produced entirely by Pettit, takes you on a quick trip comparing cities from different regions, all viewed from the International Space Station.

The MPEG 126MB version can be found here:
http://eol.jsc.nasa.gov/cities/CitiesAtNightWorldTour720X480edit7.mpg

The QuickTime 39MB version can be found here:
http://earthobservatory.nasa.gov/Features/CitiesAtNight/CitiesAtNightWorldTour360X240.mov

Las Vegas 2008
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The “Vegas Strip” of casinos and hotels—reputed to be the brightest spot on Earth—stands out in the center of this Astronaut image due to both its brightness and its diversity of light colors.

Tokyo 2008
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As more and more people move to cities, and the surrounding rural and suburban areas are increasingly developed, the pattern of lights in cities around the world will change. Nighttime photographs from astronauts document these changes, providing illustrations for the continuing story of humanity’s footprints on the Earth. For the full story visit:
earthobservatory.nasa.gov/Features/CitiesAtNight/

Sidi Toui National Park, Tunisia

1987 Earth Observatory NASA
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1999 Earth Observatory NASA
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In 1987 this desert region in Tunisia was affected by drought, agriculture, and overgrazing. In 1999 the area’s native vegetation began to return inside the park’s protected borders. The park’s area is easily discerned by the revived grassland, which appears as a deep shade of brown. The grassland’s brownish color results partly from dry wintertime conditions, and partly from the region’s overall aridity. Sidi Toui National Park was established in 1993, and as the vegetation returned, so did many birds. In 1999, local authorities introduced a small population of oryx. Prior to the park, this and several other antelope and gazelle species had been driven nearly to extinction by habitat loss.

For more information, visit
http://earthobservatory.nasa.gov/IOTD/view.php?id=35741

City Growth in Africa: Tripoli, Libya

Tripoli, Libya - 1972
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Tripoli, Libya - 2002
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These images show Tripoli’s expansion between 1976 and 2002. In these false-color images, red indicates vegetation, and the brighter the red, the more intense the vegetation. Blue-gray indicates buildings and/or paved surfaces. Beige indicates bare ground and/or fallow (unfarmed) fields. The later image shows an expanded urban area, with a blue-gray network of city streets stretching out both east and west from the city center. For more information visit, http://earthobservatory.nasa.gov/IOTD/view.php?id=35836

Penny Ice Cap Canada, 1979-2000

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Penny Ice Cap is the southernmost of Canada’s big ice caps. Located on Baffin Island, the ice cap has a maximum elevation of about 1,900 meters. Like other glaciers and ice caps in the Northern Hemisphere, the Penny has been thinning and its valley glaciers have been retreating in recent decades. A 2004 NASA study of the Penny Ice Cap showed that the lower elevations of the Penny Ice Cap had thinned by as much as 1 meter per year. Scientists are uncertain how much of the retreat is because of recent climate change (global warming) and how much of it is due to declines that have been going on since the end of a climate period called the Little Ice Age.

For more information visit
http://earthobservatory.nasa.gov/IOTD/view.php?id=9103

Wetland Damage Along the Gulf Coast 2008

Hurricane Ike from the ISS
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The Texas and Louisiana coasts show the impact of Hurricane Ike’s powerful storm surge on coastal wetlands. Hurricane Ike came ashore over southeast Texas on September 13, 2008, bringing with it a wall of water that stretched from Galveston, Texas, across all of coastal Louisiana. The surge of ocean water from the Gulf pushed far inland, inundating the wetlands. The salty water burned the plants, leaving them wilted and brown. A strip of brown lines the coast for hundreds of kilometers. Apart from damaging wetland vegetation, the powerful tug of water returning to the Gulf of Mexico also stripped marsh vegetation and soil off the land. Scientists don’t yet know how long it will take the wetlands to recover from the storm damage.

Wetland Damage Along the Gulf Coast 2008
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The Louisiana wetlands have yet to recover from damage caused by Hurricanes Rita and Katrina in 2005. For more information visit
earthobservatory.nasa.gov/IOTD/view.php?id=35521