4 . Burning coal for energy adds planet-warning carbon dioxide (CO₂) to Earth’s atmosphere. As the planet heats up, experts warn that simply cutting greenhouse gas emissions (排放) will not be enough to avoid global warming. CO₂ must also be removed from the atmosphere.

Existing experimental machines that pull CO₂ directly from the air are too expensive to be widely used. But a new effective technology to remove CO₂ already exists. It is not expensive and easy. It is forests. Planting trees and watching forests are effective ways to clean the air.

Forests used to cover large areas of the Appalachian Mountains in the eastern United States. In the state of West Virginia, coal mining let the land there bare, without trees. Over the years, coal mining and cutting forests took over 90 percent of the red spruce (云杉) forests.

Chris Barton works for the University of Kentucky. He started a group called Green Forests Work, aiming to put trees back on the roughly 400,000 hectares of land.

However, Barton explains the land has problems. “If you planted trees on these places, they just didn’t grow. The ground was too hard. Water didn’t infiltrate (渗透). The trees can’t root. Oxygen can’t circulate in those environments.” Using heavy equipment, workers tear the ground. In this way, the trees put down roots.

Barton says not everyone believes the solution is a good idea. “We’ve had a lot of doubtful look at us twice from people. But after we do it, there’s no question that it was the right thing to do.” And it has worked. Forests are coming back to the grounds.

Scientists say that, in West Virginia alone, restoring red spruce forests to the area could send what is equal to 56 million barrels (桶) of oil into the ground. But it will take time — a long time. Around the world, experts say, nature offers powerful tools to fight climate change. But patience is needed. Nature works, but slowly, in its own time.

5 . As the effects of climate change become more disastrous, well-known research institutions and government agencies are focusing new money and attention on an idea: artificially cooling the planet, in the hopes of buying humanity more time to cut greenhouse gas emissions.

That strategy, called solar climate intervention (干预) or solar geoengineering, involves reflecting more of the sun’s energy back into space — abruptly reducing global temperatures in a way that imitates the effects of ash clouds flowing out from the volcanic eruptions. The idea has been considered as a dangerous and fancied solution, one that would encourage people to keep burning fossil fuels while exposing the planet to unexpected and potentially threatening side effects, producing more destructive hurricanes, wildfires floods and other disasters.

But. as global warming continues, producing more destructive hurricanes, wildfires floods and other disasters, some researchers and policy experts say that concerns about geoengineering should be outweighed by the imperative to better understand it, in case the consequence of climate change become so terrible that the world can’t wait for better solutions.

One way to cool the earth is by injecting aerosols (气溶胶) into the upper layer of the atmosphere. where those particles reflect sunlight away from the earth. That process works, according to Douglas MacMartin, a researcher at Cornell University.

“We know with 100% certainty that we can cool the planet,” he said in an interview. What’s still unclear, he added, is what happens next. Temperature, MacMartin said, is an indicator for a lot of climate effects. “What does it do to the strength of hurricanes?” he asked, “What does it do to agriculture production? What does it do to the risk of forest fires?”

Another institution funded by the National Science Foundation will analyze hundreds of simulations of aerosol injection, testing the effects on weather extremes around the world. One goal of the research is to look for a sweet spot: the amount of artificial cooling that can reduce extreme weather events without causing broader changes in regional rainfall patterns or similar impacts.

6 . As heat waves continue to ravage the planet, air conditioners are becoming more and more common. However, these "active" cooling devices are posing problems because the electricity consumption which most people are concerned about and the release of ozone-damaging chemicals worsen the greenhouse gas effect, resulting in the creation of heat islands and further thermal pollution. Therefore, "passive" cooling, which doesn't have such effects, has attracted considerable attention from both scientists and ordinary people in recent years.

In a recent study, a team of researchers from China and US presented an eco-friendly, low-cost smart coating to keep buildings cooler while consuming zero electricity. Infrared radiation-based passive cooling has been investigated since 2014, but challenges, mainly the expensive and unsustainable design, have greatly limited their large-scale and widespread application. Besides, the imbalance in cooling ability of these coatings during the day and night tends to lead to great day-night temperature differences as more heat is lost than gained at night.

The solution therefore requires a "smart" mechanism that can both enhance daytime cooling and minimize nighttime heat loss. To do this, the researchers created a new smart coating comprised of conventional building materials, including titanium dioxide nanoparticles, fluorescent microparticles, and glass microspheres that were engineered to reflect most of the sunlight. Specifically, the titanium dioxide particles effectively reflect sunlight through light scattering（撒播）while the fluorescent particles increase the amount of reflection by changing the absorbed sunlight into fluorescence emissions, which drive more heat away from the building. Meanwhile, the glass microspheres re-send mid-infrared broadband radiation, allowing not only heat loss, but allowing heat exchange to take place between the building and the sky.

The coating was tested on a model concrete building. Through this efficient heat exchange with the sky, daytime cooling was strengthened while nighttime cooling was reduced. The building's inside temperature was always maintained at around 26℃, even when the out-side temperature varied from 24℃ to 37℃ during the day. We believe this new coating will make it to commercialization soon, enabling a sustainable, passive cooling technology that could help to fight climate change and the global energy crisis.

7 . Royal Dutch Shell is launching a $ 300 million and forestry program, at a time when an increasing number of oil companies are putting money in carbon offset (碳补偿)plans to meet climate goals. The company will spend the money over the next three years on projects to store carbon, including large forests in the Netherlands and Spain, and will start offering motorists the option of purchasing carbon offsets when they buy petrol at the pump.

The executives of the company explained that these carbon offset projects were a new business opportunity for Shell, as well as a way to meet its climate targets. “We believe that over time we will be building a business, because these carbon credits will become more valuable as carbon becomes more limited," they said. Shell recently decided to cut its net carbon footprint (碳排放)by 2-3 percent in five years, which includes emissions (排放)from the products it sells. The company plans to produce carbon credits from the forestry projects, then sell these credits on to customers buying its oil and gas products, or apply the credits to its own operations to lower its carbon footprint.

Plants absorb carbon dioxide as they grow and restoring forests and other natural areas is considered one of the simplest ways to store carbon. However, the voluntary market for carbon credits based on forestry projects has its critics, as projects in developing countries can be hard to monitor. Shell's move has also been criticized by some environmentalists. They worried that there was a risk of " greenwash when companies invested in forestry projects. "There is an entire debate about whether forestry projects truly reduce emissions or not," they said, pointing out that planting in one area could cause deforestation (滥伐森林)to another.

Shell said it would rely on the third party to ensure its forest program to meet the Voluntary Carbon Standard and strict biodiversity requirements. Mark Lewis, head of climate change investment research at BNP Paribas, said, " Planting trees to offset emissions, as far as it goes, is a step in the right direction."

8 . Many Beijing residents go to great lengths to avoid breathing the city's smoggy air, especially when it reaches critical pollution levels, but one local entrepreneur decided that canning(灌装) and selling this poor quality air as a souvenir would be a great idea. Believe it or not, he was right.

After seeing a number of companies achieve commercial success by canning fresh air from countries like France, Canada or Australia and selling it in China, Dominic Johnson-Hill, a British-born citizen of Beijing and owner of the Plastered 8 souvenir shop, decided to turn the idea on its head and sell canned Beijing air throughout China and abroad.

"I'd seen people going crazy to buy canned air from Canada and Australia, so I thought it was time to push business the other way," the entrepreneur said. "They' re perfect gifts! What else are you going to take home when you go home from Beijing? A roast duck? A Plastered T-shirt? These cans are light, portable, you can just imagine someone' s face when they unwrap (打开) it for Christmas."

The few mouth-fulls of Beijing air come in standard tin cans featuring a couple of iconic city landmarks as well as a bitter description of the contents: "a unique mix of nitrogen, oxygen and some other stuff". The ironic (讽刺的) souvenirs cost 28 RMB (US $4) and are available at the Plastered 8 shop, as well as on its online shop. But if you're actually considering buying some, you'd better ask shop in advance, as they are virtually flying off the shelves. Johnson-Hill said that his shop is selling hundreds of Beijing air cans every day.

Personally, the well-sold can probably is an awakening for the public to be concerned about the living conditions. Yet one thing that’ s not particularly clear is whether the air is really collected from Beijing, as the cans are labeled as "Made in Shenzhen". There's a big chance that' s just a kind of Plastered 8 humor, as they also list "Choking Hazard" and "May have unidentified objects inside." as warnings.

Anyway, it is probably a unique way to arouse public awareness of protecting the environment.

9 . The United Nations Environment Program is calling for urgent action to reduce growing risks from chemicals. Better management of chemicals could save millions of lives and billions of dollars. As estimated, 143,000 chemicals are now produced. Yet the report says only a small number of these chemicals have been studied for their effects on human health and the environment. It says death and disability rates are high from the unsafe use of chemical products.

Sylvie Lemmet, director of the UNEP, says poor management of chemicals has a high economic cost. For example, she says the cost is higher than the amount of overseas development aid, or ODA, for health care in sub-Saharan Africa.

She says, “If you look at the estimated cost of poisoning from pesticide (杀虫剂) in sub-Saharan Africa, only the injury and the loss of working time is estimated to be 6.3 billion US dollars in 2009. This is higher than the total ODA that is going to the health part in the same area.”

The UNEP estimates that chemical sales worldwide will increase by around three percent a year until 2050. Chemical production is moving quickly from developed to developing countries. By 2020, chemical production is expected to increase by 40 percent in Africa and the Middle East and 33 percent in Latin America. One of its biggest concerns is pollution of rivers and lakes by pesticide and fertilizer. Other major concerns are heavy metal pollution from the production of cement (水泥) and textiles (纺织品), and dioxin pollution from mining.

The UN report urges the chemical industry and governments to work together to develop safety policies. It says preventing harm costs less than fixing it.

10 . One evening, Catherine was at home as usual. As her____swung between what she was going to do with her life and their dinner plans for the evening, she was unexpectedly ___by an urgent call from her sister “Get over here! Turn on NBC and check these guys out. They are just like you…” One Facebook message and a phone interview later, Catherine____herself on a bus with 8 strangers in the middle of the sweltering desert heat of Utah, picking up trash and ___awareness about zero-waste and climate change.

With a deep____of the environment and a desire to make a __ , Catherine, Davey, and a group of self ___“environmental pick-up artists” went on a coast to coast road side trash pick-up. As they walked, sometimes only______0.9 miles in an entire day, they ____ and steadily made their way across the United States for three years, picking up a total of 201,678 pounds of trash.

Catherine and Davey____with us wonderful stories of hope and inspiration that fueled their___to continue their journey. After spending weeks silently______how she would have enough _____to fly home for their two-week spring break, Catherine found a blank, unidentified envelope____with $850 cash in the desert. Just enough to get her home and back. After their bus____outside of Denver, they unexpectedly got ____ and arrived in Yosemite National Park three weeks later, just in time for the “Yosemite Facelift” where____ from all over the state came together with a______of cleaning up trash all over the park.

Being at the right place at the right time became almost normal, and they realized that much of what they ____was more than just a coincidence. Together, their team learned to simply ____themselves to their task, and surrender to the journey.