A variety of significant, attractive short-term benefits will drive the development of mod

ern self-sufficient homes. These include security from severe weather, climate changes, and natural disasters; security from infectious diseases and related health problems; a fresh and nutritious diet; a dependable food supply; and security from global unrest.

But the real benefit of Earth Homes will be the long-term sustainability of our planet. It should be no secret that the planet is experiencing unusual weather and climate abnormalities. The 10 hottest years in recorded history have all been in the last 15 years; the 1990s were the hottest decade on record. The Midwestern heat wave of 1995 killed 669 people in Chicago. In 1996, we had a season of record heat spells, and 1997 was the single wan nest year on record—until 1998 shattered global temperature records. Record-high temperatures throughout the southern United States during the summer of 1998 forced the shutdown of Walt Disney World's water parks because of the threat of a viral encephalitis outbreak. The United Nations and insurers blame unusual weather for thousands of deaths and billions of dollars in damage.

Many scientists agree that the emissions resulting from human activities are substantially increasing the atmospheric concentration of the greenhouse gases. These increases will enhance the greenhouse effect, resulting in warming of the earth's surface. In 1990, scientists predicted that, if greenhouse gas emissions are not sharply decreased, we might experience a 1C to 3C rise in global temperatures. They suggested that we would have to cut in half our use of coal, oil, and gas in order to lower our emissions enough to maintain concentrations of greenhouse gases at the current levels.

Proof of warning includes a decrease in the amount of snow that covers the Northern Hemisphere, a simultaneous decrease in Arctic sea ice, continued melting of alpine glaciers, and a rise in sea level. Rain has even been reported for the first time in Antarctica, and an ice-free patch of ocean about a mile wide has recently opened near the North Pole.

Meanwhile, studies have shown that the carbon dioxide concentration in our atmosphere has been steadily increasing since 1958. Even though the rate of emissions from fossil fuels has been reduced, concentration has risen consistently.

In 1995, the size of the ozone hole over Antarctica doubled to about the size of Europe. For the first time in recorded history, the hole stretched over populated areas, exposing residents in southern Chile and Argentina to very high levels of ultraviolet (UV) radiation. Studies have shown that a 1% decrease in ozone in the stratosphere produces a 2% increase in UV radiation reaching the ground, posing more risks to humans.

In comparison with traditional homes the advantages of modem self-sufficient homes are______.

A．based on short-term benefits

B．based on the long-term sustainability

C．free from severe weather, climate changes, natural disasters, etc.

D．fresh and nutritious, free from global unrest