GRAND PRISMATIC SPRING, YELLOWSTONE NATIONAL PARK, WYOMING. Situated on a volcanic plateau that straddles Montana, Idaho and Wyoming, Yellowstone is the oldest national park in the world. Created in 1872, it covers 3,500 square miles and contains the world's largest concentration of geothermic sites, with more than 10,000 geysers, smoking cavities and hot springs. Grand Prismatic Spring, 370 feet in diameter, is the park's largest hot pool in area and third-largest in the world. The color spectrum for which it is named is caused by the presence of cyanobacteria, which grow faster in the hot water at the center of the basin than at the periphery where the temperature is lower. Declared a Biosphere Reserve in 1976 and a UNESCO world heritage site in 1978, Yellowstone National Park receives an average of 3 million visitors per year. [Yann Arthus-Bertrand] flew over 70 countries to document the planet's "fragile beauty." Photo of Arthus-Bertrand by Antoine Verdet. FLOCK OF SCARLET IBIS NEAR PEDERNALES, Amacuro delta, Venezuela. From the Llanos region to the Amacuro delta at the mouth of the Orinoco River, more than a third of the area of Venezuela is made up of wetlands, the habitat of choice of the scarlet ibis (Eudocimus ruber). These waders nest in large colonies in mangroves and move no farther than a few miles to seek food. Carotene derived from the shrimp, crabs and other crustaceans they eat helps create the birds' characteristic pigmentation. The scarlet ibis' feathers, once used by native populations to make coats and finery, are now a component in the manufacture of artificial flowers. This bird, sought after for its flesh as well as its feathers, is endangered today; fewer than 200,000 survive, in Central and South America. Below, an Arthus-Bertrand exhibition in Hanover, Germany, last June. Photo courtesy of Yann Arthus-Bertrand. WORKER RESTING ON BALES OF COTTON, Thonakaha, Korhogo, Cote d'Ivoire. In the 19th Century, West Africa received its first cotton seeds of the Gossypium hirsutum variety, which originated in the British Antilles and remains the most widely cultivated kind of cotton in the world. At the beginning of the 20th Century this raw material represented 80 percent of the world textile market (47 percent today), and the European colonial powers encouraged cotton production in order to break the export monopoly of the United States and Egypt. Harvested manually at a rate of 33 to 80 pounds per worker per day in tropical Africa, the cotton crop is then put through gins to separate fiber, seeds and waste. One ton of cotton yields 880 pounds of fibers and 1,200 pounds of seeds, which are processed for human consumption (as oil) or for animals (cattle cakes). In northern Cote d'Ivoire, cotton plantations, the main cash crop, take up 590,000 acres. The country's cotton output, nearly 300,000 tons, produced by more than 150,000 planters, is only a small fraction of world production; but nationally it counterbalances the agricultural domination in the south of the country, where the great plantations (cacao, palm oil, rubber, pineapple) are concentrated. AGRICULTURAL LANDSCAPE NEAR COGNAC, Charente, France. In the 19th Century, phylloxera, an aphid-like insect, ravaged the vineyards of Charente along with nearly half of all French vines. A major part of the grape stocks of this region was replaced by cereal plantings, which still predominate in the landscape. The vineyards were gradually restored around the city of Cognac, where the production of the liquor of the same name has steadily increased. Growing on chalky soil, the ugni blanc grape (known locally as Saint- Emilion) yields a wine that is distilled and aged in oak casks, giving rise to cognac. The stock currently being aged exceeds the equivalent of 1 billion bottles. The region is home to more than 15,000 vineyards in an area of 350 square miles. MIDDELGRUNDEN OFFSHORE WIND FARM, NEAR COPENHAGEN, DENMARK. Since late 2000, the world's largest offshore wind farm to date has stood in the strait of Oresund, which separates Denmark from Sweden, 1.3 miles west of the port of Copenhagen, at a depth of 10 to 16 feet. Its 20 turbines, each equipped with a rotor 250 feet in diameter, standing 210 feet above the water, form an arc with a length of 2.1 miles. With a power of 40 megawatts, the farm produces 89 million kilowatt hours per year (about 3 percent of the electricity consumption of Copenhagen). In 2030, Denmark plans to satisfy 50 percent of its electricity needs by means of wind energy (10 percent today). Although renewable forms of energy still make up only 2 percent of the primary energy used worldwide, their ecological advantages are attracting great interest. The wind-power industry boasts a 30 percent average annual growth rate in the past four years. Photos by Yann Arthus-Bertrand.