A compost (堆肥) program at the Wesley School in Los Angeles is helping kindergarten through eighth grade students to teach them ways to solve human-driven climate change. For the past year, 5, 200 pounds of food waste from the school has gone into compost containers rather than a landfill where it would just break down and produce planet-warming gases.

The school workers could have easily thrown the food waste into a city-provided green bin (垃圾箱) . But taking it out of sight, which would have been easier, would have missed the point, says science teacher Johnna Hampton. “When it’s invisible like that, they don’t see it, but they know it doesn’t sink in (心安) .”

When sixth grader Finn saw the finished compost pile, it sank in. “That’s my orange chicken in there,” he says. “That’s not just like any food. Somewhere in there is my food.”

The school will use the compost on plants around campus. Some will be offered to families that want to use it at home, and whatever is left will be donated.

Fifth grader Sloan felt so encouraged by the school’s compost program she decided to take climate action outside of school. Along with several other fifth graders, Sloane says, “We did a lemonade stand at our friend’s house and we made over $200, and we donated it.” They also helped create a petition (请愿) to replace the plastic forks and spoons in the school cafeteria with compostable ones.

Fifth grader Kingston was excited to learn his food waste will help grow new food on campus. “It feels good that you’re doing something that helps the planet, instead of just sitting and watching it get destroyed,” he says.

Jennifer Silverstein, an expert on climate, says the school’s compost program checks a lot of the boxes for effective, positive climate education to help youth understand the crisis of human-caused climate change.

Up to one fifth of the Amazon rainforest is emitting more carbon dioxide (CO2), than it absorbs, new research suggests.

Results from a decade-long study of greenhouse gases over the Amazon rainforest appear to show around 20% of the total area has become a net source of CO₂ in the atmosphere. One of the main causes is deforestation. While trees are growing, they absorb CO₂ from the atmosphere; dead trees release it again. However, the fact is that millions of trees have been lost to logging and fires in recent years.

The results of the study, which have not yet been published, have implications for the effort to combat climate change. They suggest that the Amazon rainforest, a vital carbon “store”, or “sink”, that slows the pace of global warming may be turning into a carbon source faster than previously thought. Every two weeks for the past 10 years, a team of scientists led by Professor Luciana Gatti, a researcher at Brazil’s National Institute for Space Research (INPE), has been measuring greenhouse gases by flying aircraft fitted with sensors over different parts of the Amazon basin. What the group found was startling: while most of the rainforest still retains its ability to absorb large quantities of CO₂ — especially in wetter years — one portion of the forest, which is especially heavily deforested, appears to have lost that capacity.

Gatti’s research suggests this south-eastern part of the forest, about 20% of the total area, has become a carbon source. “Each year is worse,” she told Newsnight. “We observed that this area in the south-east is an important source of carbon. And it doesn’t matter whether it is a wet year or a dry year. 2017 was a wet year, but it didn’t make any difference.”

A forest can become a source of carbon rather than a “store”, or “sink”, when trees die and emit carbon into the atmosphere. Areas of deforestation also contribute to the Amazon’s inability to absorb carbon.

Carlos Nobre, who co-authored Prof Gatti’s study, called the observation “very worrying” because “it could be showing the beginnings of a major tipping point”. He believes the new findings suggest that in the next 30 years, more than half of the Amazon could transform from rainforest into savanna (稀树草原).

In the 1990s, when an area of Brazilian rainforest in Amazon region, the size of Belgium, was cut down every year, Brazil was the world's environmental villain（反派角色）. Now, the Amazon ought to be the image of what is going right. Government figures show that deforestation fell by 70% in this region during the past decade. If deforestation had continued at the rate in 2005, an extra 3.2 billion tons of carbon dioxide—equal to a year's emissions from the EU would have been put into the atmosphere. However, Brazil is now the world leader in dealing with climate change.

But how did it break the vicious cycle（恶性循环）? There was no shortcut but a three –stage process including bans, better governance in frontier areas and consumer pressure on companies.

The first stage, from the mid-1990s to 2004, the government put its efforts into bans and restrictions. For example, every farm in the Amazon, had to set 80% of the land aside as a forest reserve. But this share was too high to reach. This was the worst period. Soybean prices were high and a vast expansion of soybean farming expanded on the south-eastern border of the rainforest.

During the second stage, from 2005 to 2009, Brazil's president made stopping deforestation a priority（优先事项）, resulting in better co-operation between different bits of the government. The area where farming was banned was increased from a sixth to nearly half of the forest.

The third stage, from 2009, was a test of whether a system of restrictions could survive as soybean expansion continued. The government shifted its focus from farms to counties of each stave. Farmers with me worst deforestation rates were banned from getting cheap credit（贷款）until those rates fell.

Brazil's Amazon policy is a success because it relied on restrictions rather than rewards, which have worked better. Brazil also changed itself into a farming superpower, so the country is possible to get a huge increase in food output without destroying the forest. But now the policies have been successful among commercial farms. Small holders care rather less about the law and respond to market pressures, so the government have to persuade them to change their ways. Deforestation has been slowed, but not yet stopped.