2 . By 2050, 68% of the global population will live in cities. That’s 2.5 billion more people than today. In Europe, three out of four of us already live in urban areas, and the consequences of that are becoming clear. Researchers estimate that nine million people die every year as a direct result of air pollution. As our cities grow and more people move into already crowded spaces, what do we need to do to transform our urban areas into healthy places to live? An increasing body of research tells us that we should be letting nature back in.

Green spaces in cities mitigate the effects of pollution and can reduce a phenomenon known as the urban heat island effect, which refers to heat trapped in built-up areas. The effect appears in towns and cities where the heat generated by people, transport and industry is trapped in the narrow roads and concrete structures, unable to escape to the atmosphere. This can bring the temperature in urban areas up 3 — 4°C higher than the surrounding countryside, and with that comes a severe cycle. Increased temperatures in summer lead to an increased demand for cooling. This expands our energy consumption, which in turn build up fossil fuel consumption, increasing pollutants in the air and harmful smog on our streets.

Planning cities to include green spaces wherever possible is the first step in making our urban areas healthier. For example, adding a layer of vegetation to rooftops and creating green roofs has proven to reduce the urban heat island effect. Trees in our streets also play their part, and a variety of tree species can have a profound effect. Simply having access to green spaces in cities can do wonders for our stress levels and concentration at work. “People need to interact with nature whenever the opportunity arises. Something as simple as a five-to-ten-minute break during the workday can improve well-being and boost productivity,” Cecil, an expert studying nature in cities says.

3 . Food waste contributes to ever-growing landfills (垃圾堆).    1     If you want to help the environment in your own way, you can start by reducing, or better yet, completely erasing food waste in your home. To give you an idea of where to start, here are some tips:

Don’t buy too much food whenever you go grocery shopping.    2     However, if your family cannot eat all the food before it goes bad, then it just adds to food waste. Taking several short grocery shopping trips every week instead of one long trip may help keep you from buying too much food, thereby cutting back on food waste.

Always make a shopping list.    3     That’s because you already know what things you need. Moreover, a list will prevent you from buying food items that you already have at home, which can help reduce the amount of potential food waste.

    4     For meats, you have to keep them in the freezer while fruits and vegetables should be stored in the crisper compartment (保鲜室). Although these tips may seem simple, they can help greatly reduce the amount of food waste that your family produces.

Use the “First-In-First-Out” method. For example, placing the newly bought foods at the back of the fridge or cupboard will encourage people to use the ones that are in the front row. This will ensure that you know what you have and reduce food waste.     5    

6 . Introduced species have a bad reputation. It has been believed that the species mix in a particular place should remain as unchanged as possible. But this is just an opinion. Other opinions are possible. A study published recently by Dov Sax of Brown University, thus asks how the benefits of introduced species might be better assessed, so that opinions can be more informed. Specifically, he identifies several aspects for that.

Initially, whether introduced species provide direct human advantage is taken into account. Dr. Sax and his colleagues ignored crops, since their benefits are obvious. But they included transplanted grass species that have gone wild，yet provide grazing(牧草)for domestic animals, and introduced forest trees that produce wood for construction.

Another factor is their possible benefit to the ecosystem into which the introduction has happened. Such introduction is sometimes made to reduce the risk of a localised species becoming extinct. Pyne’s ground plum(李子)，native to a handful of sites in the central basins of Tennessee but now transplanted to others, falls into this category.

The last value is experienced on an emotional rather than a practical level. Lots of people feel good about native wildlife, which is generally the main motive for its conservation. But that feel-good factor can extend to introduced species as well. Such value can cut both ways, however. For example, ring-necked parakeets, an Asian and African species, have been spreading through Britain for several decades. Some find them a colourful addition to the local wildlife, others a noisy competitor for native birds.

In light of their analysis, Dr. Sax and his team therefore suggest that researchers studying introduced species should in future create a clear distinction in their studies between changes that have happened and judgments about the value of those changes. In addition, when making those judgments, they should acknowledge all types of values, rather than focusing narrowly on one or two of them.

That done, many species will surely still be accused of possible damage. But others, badly thought of in the past, may not.

7 . The students stand on a pier (码头) over the Harlem River in New York City. They stare down into the brown water. Their teacher, Mr. Rodman, pulls a long rope out of the river. Fastened to the end of the rope is a metal cage and inside are oysters (牡蛎). Taking turns, the students measure all the oysters, and then compare notes. The biggest oyster is over 2 inches long, much bigger than a healthy size for its age! They also measure the level of oxygen. As more oysters grow, the water should become clearer and hold more oxygen. Also, other animals should move in.

Oysters are soft-bodied animals, and share the underwater community with plants, fish, and other life. They are food for crabs and other animals. As new oysters grow, they attach their shells to older ones，forming big reefs with many small spaces where other animals live. Oysters eat algae (藻类). If algae grow too fast，they can decrease oxygen from the water-and even fish need oxygen to breathe!

But what happened to the oysters 100years ago in New York Harbor? Before then, lots of oysters lived in these waters. They were shipped to restaurants around the world. By the early 1900s, people were eating them faster than they could grow. Pollution was pouring into the waters. The harbor became seriously polluted. Since the 1970s, new laws have helped reduce poisonous waste. Some fish started to swim through again. But oysters were still missing-until recently.

The Billion Oyster Project began in 2014 to help bring oysters back to New York Harbor. The project has recruited (招募) more than 6,500 students at more than 100 middle schools and high schools to help grow, distribute, and study the oysters.

Finally, the students put the oysters back in the cage. Mr. Rodman lowers the cage into the river. In a few months, they will check the cage again. When the oysters are big enough, they will be moved to join a healthy reef in the middle of the harbor.

9 . Coral reefs are the rainforests of the ocean. They exist on vast scales and are equally important havens of biodiversity. Reefs occupy 0.1% of the oceans.     1    

Corals are useful to people. Without the protection which reefs afford from crashing waves, low-lying islands such as the Maldives would have flooded long ago, and a billion people would lose food or income. However, reefs are under threat from rising sea temperatures. Heat causes the algae (海藻) with which corals are living together to generate toxins (毒素) that force those coral to leave.     2    

Research groups around the world are coming up with plans of action to see if that will help, such as identifying naturally heat-resistant corals and cross-breeding such corals to create a new type.     3     Without carbon reduction and decline in local, coral-killing pollution, even resistant corals will not survive the century.

Doubters doubt humanity will get its act together in time to make much difference.

    4     Carbon targets are being set and ocean pollution is being dealt with. Countries that share responsibilities for reefs are starting to act together. Scientific workarounds can also be found. Natural currents can be applied to facilitate mass breeding. Sites of the greatest ecological and economical importance can be identified to maximize bang for buck.

    5     It could serve as a blueprint for other ecosystems. Hard-core greens — those who think that all habitats should be kept unspoiled — may not approve. But when entire ecosystems are facing destruction, the cost of doing nothing is too great to bear.

10 . From Dec 7 to 19, delegates from around the world met at the 15th meeting of the Conference of the Parties to the United Nations Convention on Biological Diversity (also known as COP15), in Montreal, Canada. After two weeks of intense debate at COP15, delegates agreed on Dec 19 to adopt a landmark plan to halt and reverse biodiversity loss by 2030. “Finally, we reached our destiny. We adopted the Kunming-Montreal Global Biodiversity Framework,” Huang Runqiu, COP15 president and China’s minister of ecology and environment, announced on Dec 19.

The new framework is a commitment by 196 parties to the Convention on Biological Diversity to conserve at least 30 percent of the Earth’s land and ocean area by the next decade. It also will increase the expected annual financial assistance from developed countries through 2030 to help developing nations with biodiversity protection.

The aim of COP15 is to ensure biodiversity loss is changed by 2030, and that humans are able to live in harmony with nature by 2050.To realize these objectives can be very challenging. At COP10 in Nagoya, Japan in 2010, the parties agreed on the 20 Aichi Biodiversity Targets (爱知生物多样性目标). But, as of now, none of the 20 objectives has been fully realized.

It is important to turn consensus into effective actions. Yet, as recent talks have shown, an aspect of effective international action on stopping climate change is the cooperation of developed countries. Developed countries, however, have fallen short of their responsibility as they have failed to fulfill the obligations according to the COP convention to provide funding and technology to poorer nations who lack the means to combat climate change.

To solve this problem, the framework creates a new biodiversity fund within the UN’s existing Global Environment Facility. This came about as a compromise between developing nations, which wanted a new fund, and developed countries, which did not. In addition, a global youth initiative (倡议) was also released, hoping young people to be leaders and advocates for biodiversity conservation.