Assessment report concluded that Arctic summer sea ice extent has decreased by nearly 27 per cent in the past 50 years due, at least in part, to warming temperatures. In the past 30 years, Arctic sea ice loss has accelerated by 20 per cent compared with
previous rates. In the past two decades, sea ice thickness also has decreased at a rate of seven to nine per cent per decade.
Climate models predict that if current warming trends continue, the Arctic Ocean could be ice-free during the summer by the end of this century.

Honduras is second only to Ecuador in the production and export of cultured shrimp from Latin America. Vast areas of the delta have been converted into farms for the cultivation of shrimp.

The rapid growth of shrimp aquaculture in Honduras has caused both environmental and social problems. Shrimp farmers are depriving fishers, farmers and others of access to mangroves, estuaries and seasonal lagoons; destroying mangrove ecosys-tems, altering the hydrology of the region, destroying the habitats of other flora and fauna and precipitating declines in biodiversity; contributing to degraded water quality; and exacerbating the decline in Gulf fisheries through the indiscriminate capture of other species caught with the shrimppost larvae that are used to stock ponds.

These two images provide a visual comparison of the increase in coverage by shrimp farms in the Gulf of Fonseca over time. It is evident from the images that between 1987 and 1999, a period of about 12 years, the total area under shrimp farming has increased tremendously.

Iguazú National Park, located in Argentina near its borders with Brazil and Paraguay, contains remnants of the highly endangered Paranaense Rain Forest.

Isolated from other rain forests by natural barriers, the Paranaense developed a distinct and highly diverse ecosystem with thousands of species of mammals, birds, reptiles, and amphibians unique to the area. The famous Iguazú Falls are located within the boundaries of the National Park and are shared by Argentina and Brazil.Between1973 and 2003, dramatic changes to the landscape occurred in this region.

In 1973 the forested area spread across the borders of the three nations. By 2003, however, large areas of the forest in Paraguay and Brazil, and smaller amounts in Argentina, had been converted to other forms of land cover, creating a mosaic of differently colored land use areas. Note the variation in land cover patterns among the different countries—reflections of different land use polices and practices.

Images 300 dpi

(4663 Kb)

Iran’s Lake Hamoun is fed primarily by water catch-ments in neighboring Afghanistan. In 1976, when rivers in Afghanistan were flowing regularly, the amount of water in the lake was relatively high. Between 1999 and 2001, however, the lake all but dried up and disappeared, as can be seen in the 2001 satellite image.
The “dry phase” of Lake Hamoun is a striking example of how competition for scarce water resources can transform a landscape. When droughts occur in Afghanistan, or the water in watersheds that support Lake Hamoun is drawn down by other natural or human-induced reasons, the end result is a dry lakebed in Iran. In addition, when the lake is dry, seasonal winds blow fine sands off the exposed lakebed. The sand is swirled into huge dunes that may cover a hundred or more fishing villages along the former lakeshore. Wildlife around the lake is negatively impacted and fisheries are brought to a halt. Changes in water policies and substantial rains in the region saw a return of much of the water in Lake Hamoun by 2003.

Las Vegas is the fastest growing metropolitan area in the United States. Its growth was fairly slow during the first half of the 20th century, but as the gaming and tourism industry blossomed the population increased more rapidly. In 1950, Las Vegas was home to 24 624 people.

Today, the population of the Las Vegas Valley tops one million, not including the tourists. According to one estimate, it may double by 2015. This population growth has put a strain on water supplies.

Satellite imagery of Las Vegas provides a dramatic illustration of the spatial patterns and rates of change resulting from the city’s urban sprawl. Las Vegas is shown in the central portion of these images from 1973 and 2000. Note the profound modifications to the landscape—specifically the proliferation of asphalt and concrete roads and other infrastructure, along with the displacement of the few vegetated lands.

By 2000, Las Vegas’ growth had sprawled in every direction, with the greatest expansion to the northwest and southeast. As the city expanded, several new transportation networks emerged to serve the city’s inhabitants.

This pair of satellite images shows the impact of massive and rapid agricultural development in Almeria Province along Spain’s southern coast. In the earlier image, the landscape reflects rather typical rural agricultural land use.

In the 2000 image, much of the same region—an area covering roughly 20 000 hectares (49 421 acres)—has been converted to intensive greenhouse agriculture for the mass production of market produce. (Greenhouse-dominated land appears as whitish gray patches.)

In order to address increasingly complex water needs throughout Spain, the government adopted the Spanish National Hydrological Plan (SNHP) in 2001. Initially, this water redistribution plan involved the construction of 118 dams and 22 water transfer projects that would move water from parts of the country where it was relatively abundant to more arid regions.

In 2004, the Spanish government announced it would begin exploring more environmentally friendly water-saving technologies, such as wastewater recycling and seawa-ter desalinization.

Copsa Mica is a large industrial city located in the very center of Romania and is classified as an “environmental disaster area.” The environmentally damaged area covers hundreds of square kilometres of land. The main industries in Copsa Mica are non-ferrous metalworking and chemical processing plants, and their effect on the environment has been devastating. Air pollution by heavy metals is 600 times the allowed levels.

To make matters worse, a lead-smelting facility emitted fumes containing sulfur dioxide, lead, cadmium, and zinc on the town and surrounding area for 50 km2 (19 square miles). The entire town and much of the surrounding area were covered with a blanket of black soot daily until the facilities were forced to close in 1993.

In 1989 Copsa Mica was exposed as one of the most polluted places in Europe. It has the highest infant mortality rate in Europe, 30.2 per cent of children su?er reduced “lung function” and 10 per cent of the total popula-tion of 20 000 su?er “neurobehavioral problems.” The soil and the local food chain probably will remain contaminated for at least another three decades.

The Huang He (Yellow River) is the muddiest river on Earth and is China’s second longest river, running 5 475 km (3 395 miles) from eastern Tibet to the Bohai Sea.

The Huang He’s yellow color is caused by its tremen-dous load of sediment, composed primarily of mica, quartz, and feldspar particles. The sediment enters the water as the river carves its way through the highly erodable loess plateau in north-central China. (Loessial soil is called huang tu, or “yellow earth,” in Chinese.)
Centuries of sediment deposition and dike building along the river’s course has caused it to flow above the surrounding farmland in some places, making flooding a critically dangerous problem.

Where the Huang He flows into the ocean, sediments are continuously deposited in the river delta, where they gradually build up over time. Between 1979 and 2000—as these satellite images show—the delta of the Huang He expanded dramatically. Several hundred square kilometres of newly formed land were added to China’s coast during this period.