Millions of tons of electronic waste, known as e-waste, is produced ever year. In 2016, the world’s population make 49 million tons of electronic waste. It has been calculated that there will be more than 60 million tons by 2021. The amount of electronic waste is growing so rapidly that it has become a global problem that needs to be addressed.

What is causing the upsurge(激增)in e-waste? Technology is becoming more and more widespread, covering almost every aspect of our lives. Meanwhile, the lifespan of devices is getting shorter— many products will be thrown away once their batteries(电池)die, to be replaced by new devices. Companies update the design or software so quickly and it is usually cheaper and easier to buy a new product than to repair an old one. Since prices are falling, electronic devices are in demand around the world.

As more people buy electronic equipment, manufacturers(制造商)are beginning to face shortages of the raw material needed to make their products, so recycling and reusing materials from discarded(废弃的)products and waste makes economic and environmental sense. Recycling e-waste is practiced both formally and informally. Formal e-waste recycling usually involves taking apart the electronics, separating and sorting through the materials and cleaning them. Companies must obey health and safety rules to reduce the health and environmental harm of handling e-waste by using pollution-control technologies. All this makes formal recycling expensive.

With the amount of e-waste growing around the world, recycling alone will not be enough to handle the problem. In order to reduce e-waste, manufacturers need to design electronics that are safer, and more durable (耐用的)repairable. As a customer, you’d better get our old product repaired if possible and buy a new device only when you really need.

The deep and dark night sky is filled with wonder. Looking up at the bright stars, mysterious planets and ancient constellations (星座) brings a timeless feeling. Today, populated areas around the globe are enveloped in a type of fog that disconnects people from that amazing night sky, but reducing light pollution can help to restore the wonder.

After the sun sets, cities and suburbs across the globe are lit up with artificial lights. They glow along roads and highways and flood fields in sports stadiums. They also shine light on skyscrapers, malls, and flashing electronic signs. However, these lights negatively impact wildlife.

Artificial lighting has caused the firefly population to completely disappear in some areas, while lighthouse beams (光线) negatively impact marine species. In fact, in the US and Canada, 18 species of firefly are now classified as being threatened with a high risk of extinction in the next ten years.

Just leaving that light on affects the behavior of nocturnal pollinators (夜间传粉者) like moths, causing them to fly towards the light and not the flowers. This, in turn, negatively affects plants’ abilities to bear fruit and reproduce.

Many people are aware of many types of pollution including air, water, and land, but few realize that strong artificial lighting is harmful to all mammals, including humans. In order to make people aware of the importance of darkness, researchers wrote a world atlas (地图册) of artificial night sky brightness, which is published in Science Advances. Their findings reveal that 80 percent of the world populations live under a sky glow, with more than 99 percent of Americans and Europeans living under light-polluted skies.

Although individuals cannot control the highway and city lights, they can make a difference at home. And if everyone were to “turn off the switch”, it could help to bring back natural darkness in some areas. Light areas where light is needed and aim the light beams downwards. Try to use low-level lighting and be aware that some surfaces reflect more light into the sky.

A global climate agreement has been finalized in Paris. The goal of preventing what scientists regard as dangerous levels of climate change—judged to be reached at around 2℃ of warming above pre-industrial times—is central to the agreement.

The world is already nearly halfway there and many countries argued for a tougher target of 1.5℃—including leaders of low-lying countries that face unsustainable sea levels rises in a warming world. The desire for a more ambitious goal has been kept in agreement—with the promise to “attempt to limit” global temperatures even more, to 1.5℃.

Dr Bill Hare, CEO of Climate Analytics, says the objective is “remarkable”. “It is a victory for the small islands, the least developed countries and all those with the most to lose”.

Meanwhile, for the first time, the agreement lays out a longer-term plan for reaching a peak in greenhouse emissions(排放) “as soon as possible” and achieving a balance between output of man-made greenhouse gases and absorption—by forests or the oceans—“by the second half of this century”.

“If agreed and implemented(履行), this means bringing down greenhouse-gas emissions within a few decades. It is in line with the scientific evidence we presented,” says John Schellnhuber, Director of the Potsdam Institute for Climate Impact Research.

“The Paris Agreement is only one step on a long road, and there are parts of it that frustrate and disappoint me, but it is progress,” says Greenpeace International executive director Kumi Naidoo. “This deal alone won’t dig us out the hole we’re in, but it makes the sides less steep.”