1 . Like all people who live long enough, I have been through many dark periods and seen so much suffering. I was in New York on that terrible day in 2001, that day when our world changed forever. I still can remember the disbelief, the fear, the confusion as the city went quiet except for the alarms on the police cars and ambulances.

It was ten years after that day that I was introduced to the Survivor Tree, a pear crushed between two towers. All that was left was half a trunk that had been burnt black, with roots that were broken and only one living branch.

She was almost sent to the dump, but the young woman who found her, Rebecca Clough, begged that the tree might be given a chance. And so she went to be cared for in a nursery in the Bronx. Bringing that seriously damaged tree back to health was not an easy task, and it was touch and go, which cost a lot of patience and determination.

Eventually the tree made it. She was returned to be planted in what is now the 9/11 Memorial & Museum. In the spring, her branches are bright with blossoms. I’ve seen people looking at her and wiping away tears. She truly is a symbol of the resilience of nature—and a reminder of all that was lost on that terrible day 20 years ago.

There’s another, even more dramatic story about survivor trees. In 1990 I visited Nagasaki, the city where the second atomic bomb was dropped at the end of World War II. Scientists predicted that nothing would grow for decades. But, amazingly, two 500-year-old camphor trees had survived. Only the lower halves of their trunks remained, and from those most of the branches had been torn off. Not a single leaf remained. But they were alive.

Now it’s a large tree, but its thick trunk has cracks and you can see it’s all black inside. But every spring, that tree puts out new leaves. Many Japanese regard it as a holy monument to peace and survival. I stood there, humbled by the destruction we humans can cause and the unbelievable resilience of nature.

What a fascinating world, the nature kingdom. Whenever you give her a chance, nature returns. Human beings should understand how much we actually depend on the natural world, physically and spiritually.

If corals go, divers and marine biologists are not the only people who will miss them. Reefs take up a fraction of a percent of the sea floor, but support a quarter of the planet’s fish biodiversity. The fish that reefs     1     are especially valuable to their poorest human neighbours, many of whom depend on them as a source of protein. Roughly an eighth of the world’s population lives within 100km of a reef. Corals also protect 150,000km of shoreline in more than 100 countries and territories from the ocean’s buffeting, as well as     2     billions of dollars in tourism revenue. In the Coral Triangle, an area of water stretching across South-East Asia and into the Pacific which is home to three-quarters of known coral species, more than 130m people rely on reefs for food and for their livelihoods in fishing and tourism.

Measures to mitigate climate change are needed regardless of coral, but even if the world’s great powers were to put their shoulder to the problem, global warming would not be brought to a     3     halt. Coral systems must adapt if they are to survive, and governments in countries with reefs can help them do so.

Corals need protection from local sources of harm. Their ecosystems suffer from coastal run-off, whether sewage or waste from farms, as well as the sediment dumped from beach-front building sites. Plastic and other debris block sunlight and spread hostile bacteria. Governments need to     4     tighter rules on these industries, such as tougher local building codes, and to put more effort into enforcing rules against overfishing.

Many reefs that have been damaged could benefit from     5    . Coral’s biodiversity offers hope, because the same coral will grow differently under different conditions. Corals of the western Pacific near Indonesia, for example, can withstand higher temperatures than the same species in the eastern Pacific near Hawaii. It seems that     6     the hardiest types and encouraging them to grow in new spots is a way forward, though an expensive one. A massive project of this sort is under way in Saudi Arabia as part of a tourism     7    .

More drastic intervention to head off the larger threats corals face should also attract more     8    . Shading reefs using a polymer film as a sunscreen to cool them is under discussion for parts of the Great Barrier Reef. Other schemes to help corals involve genetic engineering,     9     breeding and brightening the clouds in the sky above an area of the reef by spraying specks of salt into the lowest ones, so that they deflect more of the sun’s energy. These measures may sound     10    , but people need to get used to thinking big. Dealing with the problems caused by climate change will call for some radical ideas.

China's Worst Sandstorm

China's worst sandstorm in a decade caused mass disruptions on Monday as vast swathes (广大地区) of the country were thrown into a thick, orange haze of dust and sand,     1    (force) authorities to cancel hundreds of flights, shutter roads and schools, and suspend outdoor activities.

In Beijing, poor visibility paralyzed traffic as residents posted photos of skyscrapers seemingly     2     (disappear) into the fog and compared images of the haze to scenes in the dystopian 1982 film Blade Runner.

Beijing and 23 other cities recorded “off the chart”levels of air pollution, according to state media. In Beijing, PM 10, a measure of tiny particles in the air often     3     (associate) with sandstorms, hit more than 9, 000 micrograms per cubic meter, or 180 times the level considered healthy by the World Health Organization. Some residents said they were wearing two masks even while indoors.

Officials in neighboring Mongolia, after the sandstorm     4     (emerge) before sweeping across northern China, were searching for more than 80 herders who had gone missing.

China's National Meteorological Center said it expected 12 provinces and municipalities — an area covering about 160, 000 square miles, about the size of California —     5     (affect) by the storm. The National Health Commission advised residents to stay indoors, seal windows and doors, and to use humidifiers and wet cloth     6     (deal) with any dust.     7     residents must go outside, they should wear a mask, a hat or scarf to protect their face.

8 . Mary kept tossing and turning in her sleeping bag. It was late in the night. She had been a school counsellor in the summer camp for a year now. She took care of young children who were as young as seven. That night, she was having a bad dream. In it, she was running desperately towards a river. She kept shouting, “Fire!”

Mary was awake. She realized that she had been shouting in her sleep. Suddenly, she smelled smoke. Then she saw shadows dancing against the walls of the tent. Mary jumped up and hurried to the opening in the tent. A tree was on fire! Fanned by the wind, the fire leaped up hungrily to devour everything in its path. It was going to spread to the tents very soon.

Time was of essence so Mary pulled the four children instantly out of their sleeping bags. “Fire! Fire!” She yelled, as loudly as she could.” Wake up! Get up!” After that, Mary ran back to her tent and grabbed all the sleeping bags she could carry. By then, everyone had emerged from their tents. Their faces were etched with confusion. Mary took the youngest child by the hand. Knowing that the sleeping bags would be useful, Mary pulled them along. Everyone quickly but calmly followed her. They held on to each other, in solemn silence.

After they ran to the river, Mary pulled the children into the water. Then she got into it herself. She dragged the sleeping bags in. She pushed them under the water until they were soaked. Mary was not surprised that all the trees were on fire. It had been an extremely hot season and everything in the forest was dry. Soon, they saw many animals racing to the river. Deer, rabbits and squirrels splashed into it. By then, the fire roared. Mary and other adults grabbed the wet sleeping bags and pulled them over the children’s heads.

Everything around them was bright orange and the sleeping bags had to stay wet. They made a final effort to splash water over all the sleeping bags and hid under the water.

The heat and smoke finally ended. Mary raised her head and looked around. To her relief, all the children had escaped unhurt. People all called out, “You saved our lives.” Mary suddenly thought of the dream she had.

9 . Most animal species in the world have developed some sort of natural camouflage that helps them find food and avoid attack. The specific nature of this camouflage varies considerably from species to species.

Camouflage develops differently depending on the physiology and behavior of an animal.    1    

An animal's environment is often the most important factor in what the camouflage looks like. The simplest camouflage technique is for an animal to match the "background" of its surroundings.

Since the ultimate goal of camouflage is to hide from other animals, the physiology and behavior of an animal's predators or prey is highly significant.     2    . For example, there’s no point in an animal replicating the color of its surroundings if is main predator is color-blind.

In addition to background-matching coloration, many animals have distinctive designs on their bodies that serve to conceal them. These designs, which might be spots, stripes or a group of patches, can help the animal in a couple of ways. First, they may match the pattern of "the model", the background of the animal's surroundings. Second, they may serve as visual disruptions. Usually, the patterns are positioned out-of-line with the body's contours (外形).     3    . This makes it hard for the predator to get a clear sense of where the animal begins and ends — the pattern on the body seems to nun of in every direction.

Other animals use a more aggressive sort of mimicry. Several moth species have developed striking designs on their wings that resemble the eyes of a larger animal. The back of the hawk moth caterpillar actually looks like a snake head, a frightening visage for most predators he moth would come across.

Mimicry is a different approach than ordinary camouflage, but it works toward the same end. By developing a certain appearance, an animal species makes itself a harder target for predators and a sneakier hunter for prey. As animal species evolve, they become more and more in tune with their environment.     4    . After all, being entirely overlooked by a predator is preferable to having to put up a fight.

10 . French adventurer-scientist Roland Bourdeix has a grand vision for how to preserve a thousand or more genetic varieties of coconut trees. Imagine, as he does, turning dozens or hundreds of remote Pacific islands into coconut sanctuaries. Each island would contain just a few varieties of these trees.

But why? Are coconut trees, the source of oil and newly trendy coconut water, somehow in danger?

Not exactly. At least not for now. There are plenty of coconut palms all over the tropics, and coconut production has been slowly growing. But that masks a potential long-term problem, says Stephan Weise, Deputy Director General for Research at Bioversity International in Rome. Most coconut production comes from a small part of the coconut’s gene pool (基因库). Producers rely on a handful of high-producing varieties or hybrids (杂交品种). Those commercial varieties are slowly overwhelming (压倒)traditional varieties that people in the tropics have grown thousands of years. Those are the storehouse of the coconut’s genetic diversity: All of the colors, shapes, tastes, and survival tools that this species possesses — and may need again someday.

Conserving (保护)such diversity in agricultural crops is a familiar problem, but the situation with coconuts is a little bit different, Weise says.

First of all, scientists can’t yet preserve a particular kind of coconuts in refrigerated “gene banks,” as they do with standard seeds. They can’t dry, freeze, and preserve coconuts for decades. Instead, coconuts have to be preserved as living trees, growing outside.

This leads to the second problem. Coconut varieties growing in the open air often won’t reproduce themselves successfully. Their flowers pick up pollen (花粉)from other trees nearby, which often turn out to be commercial varieties or hybrids. And when that happens, some genes may be lost altogether.

So what’s the secret to preserving these coconuts? For starters, scientists have set up a dozen open-air coconut gene banks. They’re reproducing each variety through careful hand-pollination of the trees. But Weise says that’s expensive and labor-intensive.

This brings us back to Roland Bourdeix’s crazy-sounding idea. The key to preserving coconut biodiversity more cheaply, he thinks, is isolation. And there’s no more isolated place than a lonely Pacific island. Just convince people on one of these islands to plant coconut trees from a single variety, and the problem is practically solved. He’s found several islands where the inhabitants are willing to help turn his vision into reality. One of them is well-known already: The Tetiaroa Atoll in French Polynesia, an idyllic retreat once owned by Marlon Brando.