この英文を訳してください
On August 19, 2000, the New York Times reported that an icebreaker cruise ship had reached the North Pole only to discover this famous frozen site was now open water. For a generation that grew up reading the harrowing accounts of explorers such as American Richard Byrd trying to reach the North Pole as they battled bitter cold, ice, and snow, this new view taxed the imagination.
In its many earlier trips to the North Pole, the cruise ship had allowed passengers to disembark in order to be photographed standing on the ice. This time, the ship had to move several miles away to find ice thick enough for the photo session. If the explorers of a century or so ago had been trekking to the North Pole in the summer of 2000, they would have had to swim the last few miles.
Media reports of melting ice typically focus on individual glaciers or ice caps, but the ice is melting almost everywhere. Given that the 14 warmest years since recordkeeping began in 1866 have all occurred since 1980, this does not come as a surprise.
Water shortages are also in the news. Some of the world's major rivers are being drained dry, failing to reach the sea. Among them is the Colorado, the major river in the southwestern United States. In China, the Yellow River, the northernmost of the country's two major rivers, no longer reaches the sea for part of each year. In Central Asia, the Amu Darya sometimes fails to reach the Aral Sea because it has been drained dry by upstream irrigation.
Wells are going dry on every continent. As population expands and incomes rise, the demand for water is simply outrunning the supply in many countries. Those with money drill deeper wells, chasing the water table downward. Those unable to deepen their wells are left in a difficult position.
The situation promises to become far more precarious, since the 3.2 billion people being added to world population by 2050 will be born in countries already facing water scarcity. With 40 percent of the world food supply coming from irrigated land, water scarcity directly affects food security. If we are facing a future of water scarcity, we are also facing a future of food scarcity.
Since agriculture began, the earth's climate has been remarkably stable. Now the earth's temperature is rising, apparently due to the greenhouse effect—the warming that results from the rising concentration of heat-trapping gases, principally carbon dioxide (CO2), in the atmosphere.
This rise in CO2 concentration comes from two sources: the burning of fossil fuels and deforestation. Each year, more than 6 billion tons of carbon are released into the atmosphere as fossil fuels are burned. Estimates of the net release of carbon from deforestation vary widely, but they center on 1.5 billion tons per year.
The release of CO2 from these two sources is simply overwhelming nature's capacity to fix carbon dioxide. When the Industrial Revolution began in 1760, carbon emissions from the burning of fossil fuels were negligible. But by 1950, they had reached 1.6 billion tons per year, a quantity that was already boosting the atmospheric CO2 level. In 2000, they totaled 6.3 billion tons. (See Figure 2-1.) This fourfold increase since 1950 is at the heart of the greenhouse effect that is warming the earth.
The carbon emissions of individual fossil fuels vary. Coal burning releases more carbon per unit of energy produced than oil does, and oil more than natural gas. The global fleet of 532 million gasoline-burning automobiles, combined with thousands of coal-fired power plants, are literally the engines driving climate change.
In addition, in recent years the world has been losing 9 million hectares of forest per year. Forests store easily 20 times as much carbon per hectare as does land in crops. If the net loss of forests can be eliminated, this source of carbon emissions will disappear. In the northern hemisphere, the forested area is actually increasing by 3.6 million hectares a year.
