1 . Ever been hungry enough to eat a house? Now, you actually could.

Food waste is a big problem in Japan and globally. Japan produced around 5.7 million tons of food waste in 2019. The government plans to reduce that by around 2.7 million tons by 2030. Tokyo University researchers Kota Machida and Yuya Sakai have developed a way to transform food waste into cement(水泥) for construction use and more. This is the first-ever process created for making cement entirely from food waste. The researchers say their product is four times as strong as traditional concrete. This particular cement can be used to make things like tea cups or chairs as well. However, there’s one additional feature — it’s also edible(可食的).

Kota and Yuya are the intelligence behind the formation of Fabula Inc., a company with purposes of reducing food waste, and helping fight global warming.

As expected, something this unique took years to develop. It took a few attempts to find just the right process. Kota and Yuya created the unique technology while researching possible environmentally-friendly materials to replace cement-based concrete. Cement production accounts for 8% of the world’s carbon dioxide emissions.

After a few failures, they realized they could get the cement to bind(黏合) by adjusting the temperatures. “The most challenging part was that each type of food waste requires different temperatures,” Yuya said. So the researchers had to observe them and respond in time. In the experiments, Kota and Yuya have successfully made cement using tea leaves, coffee grounds, cabbage and even lunchbox leftovers.

Fabula Inc. is currently working to make tea cups and furniture, but Yuya is thinking a little bit bigger. Their product could provide relief in the form of edible emergency shelters in disaster ones. “For example, if food cannot be delivered to the people, they could eat makeshift beds made out of food cement,” he said. To eat the material, a person needs to break it apart and boil it.

The Students’ Union

Looking for a fun Earth Day activity? You may want to try plogging------picking up litter while jogging. Strange as it may sound, the new “sport” is becoming popular with runners worldwide, many of whom are posting photos of images holding bags of trash on social media.

Derived from（起源于）the word jogging and “plocka upp”, the Swedish phrase for pick up, plogging is the idea of Erik Alstrom. In 2016, after moving to Stockholm from northern Sweden, Alstrom was shocked by the amount of rubbish there, so he began incorporating（将…包括在内）picking up rubbish into his daily runs.

Other joggers soon joined Alstrom, and by the end of 2016, plogging had appeared all across Sweden. As plogging became popular on social media, the new “sport”   began to spread beyond Sweden, first to other European countries and then worldwide.

The official online “Plogga” group now includes members from over 40 countries. Many school running clubs are also getting in on the action, posting photographs of themselves after going plogging together, or staging competitions that reward the runners with the heaviest trash bags.

As it turns out, plogging is not only good for the environment but also for people’s   health. According to Swedish fitness app Lifesun, an average person burns about 288 calories while plogging for half an hour. This is about 50 calories more than he/she would burn when just jogging. Additionally, lowering the body to pick up litter increases the plogger’s flexibility, while carrying around the increasingly heavy garbage bags helps strengthen his/her arm muscles.

This Earth Day, be sure to put on your running shoes, take a trash bag or two, and go plogging. Or better still, start a plogging team at school, or around your neighborhood, and make every day Earth Day!

7 . “The fact that the smoke reached São Paulo and blackened an afternoon proves how unusual the fires that burn in the countryside of Brazil are,” Ricardo Mello, head of the World Wide Fund for Nature's (WWF) Amazon program, said.

The latest figures come at a time of international protest against the inaction of President Jair Bolsonaro's administration. In July, Brazil's National Institute for Space Research (INPE) showed data to the public, which indicated that there had been a significant rise in deforestation (毁林) rates. Particularly, the figures showed that in July 2019, deforestation had increased nearly 300 percent in comparison to the same month in 2018.

Environmentalists are becoming increasingly concerned, accusing the government of encouraging deforestation and those who want to make use of the forest for commercial gain. During his time in power, Bolsonaro has moved to rob some power of government agencies that are responsible for protecting the rainforest as well as regulations covering native lands and nature reserves. Bolsonaro sees these kinds of regulations as a drag on economic growth in the Amazon region.

Fire in the Amazon is used as a technique to clear land for agriculture. “Farmers clear cut land to make way for agriculture, and then wait for the dry season to set fire to clear the land so they can plant，” Mello said. “It's likely that all of these forest fires are deliberately set by humans.”

Now it is the dry season in the Amazon, which means conditions in many parts of the rainforest are suitable for the fires to spread over large areas. “It is very unlikely that those fires break out naturally，” Mello said. “It is important to remember that 2019 is not a strong El Niño year. When we have strong El Niños, weather gets drier in the northern part of Brazil and this favors fires. This is not the case of 2019.”

8 . Average age is rising around the world——a demographic (人口统计)change that may pose a significant challenge to efforts to slow down climate change.

Hossein Estiri at Harvard University and Emilio Zagheni of the Max Planck Institute for Demographic Research, Germany, have found that energy use increases as we get older, and not just because we tend to get wealthier. An ageing population could mean a greater proportion of society with higher energy use, their study suggests.

They combined two decades, worth of data from thousands of US households and used this to build a model to reveal how energy use varied across 17 age groups between 1987 and 2009. They found that, on average, children's energy consumption (消耗)climbs as they grow up, before dipping slightly when they leave home. Consumption then rises again when people hit their 30s, before briefly dropping after 55, and then beginning to climb again. The study involved factors such as income, local climate and the age, type and size of a person's home. The increase in energy use at various points in our lifespan (寿命)seems to be the result of life style and how our needs change as we age.

Why does demand grow so much in our 30s? “We need more of everything. More space, a bigger TV two fridges," says Estiri. The study found that, in warmer parts of the US, energy use increases in people over the age of 65—probably as a result of increased use of air conditioning, This suggests that there is a feedback effect between climate change and an ageing population that will only make matters worse.

Heat waves have become more common in the US in recent years and are expected to become more frequent due to global warming. More older people using more electrical energy to keep cool as temperatures rise could add to emissions (排放)，and thus drive more warming until our energy supply becomes entirely fossil fuel-free.

“This confluence (汇集)of population, ageing and climate change on energy demand is really important to start thinking about," says Estiri. Benjamin Sovacool at the University of Sussex, UK, says the work shows the importance of demographics when it comes to cutting carbon emissions. Most modelling of climate change mitigation (减缓气候变化的模型) assumes people's energy consumption either stays the same or only changes by a small amount over time.

"This study directly challenges that entire body of research by forcing it to fight with the temporality and complexity of the consumption of energy, says Sovacool.

Catherine Mitchell at the University of Exeter, UK, says the research could have an important influence on policy makers. "What the paper says is that there is a lot of work about how buildings use energy, but probably not enough about how the people in them use energy," she says.

9 . Clothing rental is a hot new industry and retailers (零售商) are demanding to get on board in hopes of attracting green shopper.

But is renting fashion actually more environmentally-friendly than buying it, and if so, how much more? Journalist and author Elizabeth Cline investigated (调查) this question and concluded that it's not as sustainable as it seems.

Take shipping, for example, which has to go two ways if an item is rented — receiving and returning. Cline writes that consumer transportation has the second largest carbon footprint of our collective fashion habit after manufacturing.

She writes, ''An item ordered online and then returned can send out 20 kilograms of carbon each way, and increases up to 50 kilograms for rush shipping. By comparison, the carbon impact of a pair of jeans purchased from a physical store and washed and worn at home is 33.4 kilograms, according to a 2015 study by Levi's.''

Then there's the burden of washing, which has to happen for every item when it's returned, regardless of whether or not it was worn. For most rental services, this usually means dry cleaning, a high impact and polluting process. All the rental services that Cline looked into have replaced perchloroethylene (氯乙烯), a carcinogenic (致癌的) air pollutant, still used by 70 percent of US dry cleaners, with alternatives, although these aren't great either.

Lastly, Cline fears that rental services will increase our appetite for fast fashion, simply because it's so easily accessible. There's something called ''share washing'' that makes people waste more precisely because a product or service is shared and thus is regarded as more eco-friendly. Uber is one example of this, advertised as ''a way to share rides and limit ear ownership.'' and yet ''it has been proven to discourage walking,bicycling, and public transportation use.''

Renting clothes is still preferable to buying them cheap and throwing them in the dustbin after a few wears, but we shouldn't let the availability of these services make us too satisfied. There's an even better step — that's wearing what is already in the closet.