1 . In the wild, polar bears spend much of their lives wandering pack ice (浮冰群) in search of food. These bears have adapted to a high fat diet from ocean-going animals: they are rapid and dangerous swimmers, allowing them to easily catch animals as food. Each summer, as the pack ice starts to become smaller, polar bears draw closer to land to give birth to and care for babies. Many give up food during this period, hunting again when the ice returns and living on stored fat.

Pack ice is decreasing globally. When it does form, it disappears more quickly, and tends to be thinner as well. In 2004, several polar bear deaths by drowning were recorded. The bears had been trapped on faraway areas of floating ice, and had tried to swim for land. Due to the disappearance of the ice, they were tired and drowned before reaching shore safely. This problem is likely to grow as the pack ice becomes smaller.

The disappearance of the ice has other impacts for polar bears: they are losing their natural prey (猎物), who are also affected by the loss of habitat. The bears are not very good at catching land animals, and must compete with other species for these food sources. Land animals also don’t provide the high fat diet that polar bears need, which may lead to hunger. Hungry mothers may not be able to provide their babies with the nutrition needed, which will further contribute to the drop in polar bear population.

The deadly factors brought about by global warming put polar bears at risk. Drops in birth and survival rates have already been documented, and biologists are increasingly concerned   about the animals’ odd behavior as a result of the loss of their natural habitat. Environmental organizations believe a global effort is needed to fight against global warming before it is too late for polar bears, as well as many other species that call Earth home.

2 . In the U. S. state of Washington, a road called Interstate 90 cuts through a wild mountainous area to reach the city of Seattle. For the area's many kinds of animals, the busy highway greatly limits their movements. Animals need to move to find food, to find mates and to find new places to live. Crossing I-90 as the road is called is a risky but sometimes necessary act. But soon, animals will have a safer choice.

To help the animals, the state is finishing work on its largest-ever wildlife bridge. The 11-meter-tall, 20-meter-wide bridge begins in the forest. Workers are adding fencing anti-plants to help guide the animals across the bridge. The I-90 bridge is part of a growing number of wildlife crossings across the United States. Some are fences, some are overland bridges, and some are underpasses. They all aim to keep drivers and animals away from each other.

A U.S. Transportation Department study found crashes between animals and humans rose year by year. The accidents made up about 5 percent of all crashes nationally, and cost the economy about $8 billion. Such costs come from car repaid, emergency room visits and removal of the dead animals on roads. Collisions between animals and drivers are rarely deadly to people. But they are often deadly to wildlife. The study also found that 21 endangered or threatened species in the U.S. are affected by vehicle hits.

Patty Garvey Darda of the U. S. Forest Service says the $6-million bridge will one day pay for itself because the highway will not have to be fully or partly closed each time a large animal is struck. “If you shut down Interstate 90, you shut down interstate trade.” she adds.

4 . Today，there are thousands of national parks all over the world.    1     In that year，the United States government gave a large piece of land to the state of California.They ask the state to create a special park to protect the mountains and forest in the area.The trees in this area are called sequoias.    2     They are the tallest living things in the world and are not found anywhere else on Earth.

Conservationists in other countries saw what happened in California and soon began to do the same.Today Europe has over 350 national parks.The first one in France，Vanoise National Park，was created in 1963 because the government wanted to stop a plan to build a large tourist project there.The idea of creating a national park was first discussed in the 1940s，but people couldn’t agree on what size to make the park.    3     Ecologists worked with the government to finally agree on a plan that protected the animals，while still allowing some tourism.

    4    Like the first California park，the Bavarian Forest National Park was created to protect mountains and trees.It is the largest area of protected forest in Europe.The park has shelters where visitors can spend a night close to nature.In some places high up in the mountains，there are steps cut into the rock.    5     Thousands of tourists go to the park each year.They walk through the attractive woods and enjoy the wonderful mountain views.

6 . The world’s insects are hurtling down the path to extinction, threatening a “catastrophic collapse of nature’s ecosystems”, according to the first global scientific review. More than 40% of insect species are declining and a third are endangered, the analysis found. The rate of extinction is eight times faster than that of mammals, birds and reptiles.

“It should be of huge concern to all of us, for insects are at the heart of every food web,   they pollinate the large majority of plant species, keep the soil healthy, recycle nutrients, control pests, and much more. Love them or loathe them, we humans cannot survive without insects, ” said Prof Dave Goulson at the University of Sussex in the UK.

The analysis, published in the journal Biological Conservation, says intensive agriculture is the main driver of the declines, particularly the heavy use of pesticides. Urbanization   and climate change are also significant factors.

One of the biggest impacts of insect loss is on the many birds, reptiles, amphibians and fish that eat insects. A small number of adaptable species are increasing in number, but not nearly enough to outweigh the big losses.

Matt Shardlow, at the conservation charity Buglife, said: “It is gravely sobering to see this collation of evidence that demonstrates the pitiful state of the world’s insect populations. It is increasingly obvious that the planet’s ecology is breaking and there is a need for an intense and global effort to stop and reverse these dreadful trends.”

10 . Twelve years ago, a young traveler named Rhett Butler from San Francisco, California, visited the Sabah rainforest on Malaysian Borneo. In one area of the rainforest, he watched a bird flying through the trees. The beautiful sight left quite an impression on him. But weeks later, back home, Rhett Butler got the news that trees had been cut down in the area he visited.

That experience led Rhett Butler begin writing a book about rainforests and threats to their existence. But he did not publish the book. Instead, in 1999, he used his research for the book to create a website. The site is Mongabay. Com. His purpose was to inform the public about tropical rainforests. But the subject quickly developed. As a former businessman, he became a respected writer of science and environmental stories.

The popularity of Mongabay. Com attracted advertisers. Small ads on the site pay for its operations. Mongabay.Com has grown and led to other sites. For example, there is a site for children which is called kids. Mongabay.Com. Another one, WildMadangascar.Org, is all about the island nation that Rhett Butler calls his favorite place.

To keep his website going, he travels around the world on several major trips each year. His working tools are a laptop computer, cameras and sometimes diving equipment. He often calls on experts for information. For example, he interviewed Alison Jolly, a top experts on lemurs(狐猴). He interviewed Rodney Jackson, a biologist who established the Snow Leopard Conservancy.

Stories like these have made Mongabay a favorite place on the Internet for researchers, students and teachers. In April, Time.Com named it one of the fifteen top climate and environment websites in the world.