Saihanba is a green miracle passed on from generation to generation.

The Saihanba Forest Farm is the world’s largest manmade forest, a 750-square-kilometer barrier (屏障), 300 kilometers north of Beijing, planted to save the Chinese capital from desertification (the gradual change of habitable land into desert, which is usually caused by climate change or by destructive use of the land).

Today, overlooking the sea of green, it would be hard to imagine that a half century ago, the area was wasteland.

The big change began 59 years ago with the effort of a group of foresters and engineers who were determined to turn the area into a forest. In 1962, the Ministry of Forestry Saihanba Mechanical Forest Farm was formally established. Some 369 young people from different parts of the country went all the way north to Saihanba.

Food and shelter was in short supply, so the group grew their own potatoes and corn and set up simple shelters and tents, sometimes using only brunches and straw that gave little shelter from the freezing wind.

In the beginning, planting trees on the very cold highland was an impossible task due to the high winds. Over 90 percent of the young seedlings planted in the first two years died and the forest farm was nearly shut down. After trying different ways of planting trees, the survival rate of the newly planted young trees topped 90 percent in 1964.

Planting trees is not enough. Carefully protecting the woods and managing well the whole forest farm is even harder. That is what later generations will do.

During fire prevention periods in spring and autumn, they check the vast expanse of forest every 15 minutes during the day, and once an hour at night.

Now as third-generation tree planters in Saihanba, they need to solve even more difficult problems in the never-ending effort of planting more trees. Since there is much less flat land left for planting trees, they have to work on the rocky mountain slopes (斜坡) where the topsoil is only 10 centimeters thick. But before giving the young trees a home, they need to dig holes about 40 centimeters deep.

Three generations of hard work have turned Saihanba from a nascent (新生的) stand of trees into a million acres of forest, from a desert into an oasis.

Extracting CO2 from the air is one of the best ways to address climate change without preventing billions of people from getting the energy they need. But the trick is what to do with it afterwards.

Common approaches include injecting it deep underground to get rid of it. But if you could use it to make useful stuff, then it would do double duty and make the products zero-carbon since they wouldn’t put extra carbon into the atmosphere. For years, focus has been on making zero-carbon petrol or jet fuel from the extracted carbon using non-fossil fuels to generate the energy needed.

Today, XPRIZE revealed the two winners in this year’s 20-million-dollar prize for a contest developed to create breakthrough carbon technologies that turn emissions into products with a high net value. The winners were CarbonCure of Canada and CarbonBuilt of California. Interestingly, they both demonstrated technologies focused on decarbonizing the concrete industry.

CarbonBuilt developed a technology that reduces the carbon footprint of concrete by more than 50% while reducing raw material costs. During the curing process, CO2 is directly injected into the concrete mixture where it is chemically transformed and permanently stored.

CarbonCure’s technology enables the production of concrete with a reduced water and carbon footprint while increasing the material’s reliability. The CO2 is transformed into a permanently embedded mineral which can then be combined with new concrete mixes. The technology is able to reduce the material costs and increase profitability for producers.

Concrete is a major contributor to global warming as producing it releases a huge amount of carbon dioxide. Yet it’s the most widely used artificial material, second only to water. Renewable energy sources use much concrete per unit energy produced. If they are to increase enough to make a difference in time to help the planet, getting control of the CO2 in concrete production is essential.

A million species are facing extinction. A million, that is enough to make most scream. Some species are becoming extinct because of poaching （偷猎）.Even Namibia, which has a spectacular conservation record, hasn't been safe from that. Since 2015, poaching has caused the loss of 50 black rhinos （犀牛）annually in Namibia.

Globally, there is a $ 23-billion-a-year trade in illegal wildlife products. Driven by a demand in some countries, where the rhino horn （角）is thought to be a cure for some diseases, it sells for up to $ 100,000 per kilo on the black market. This illegal trade is making some people very rich, but it isn't rural Africans. Here, poor people are convinced to trade the life of a rhino for a few hundred dollars, which may bring the possibility of years in prison. In fact, rhino horn is made mostly of keratin, the same substance as found in our fingernails and hair.

To help slow down this reality, I took a trip to Namibia, determined to make a difference to black rhino conservation. The first stop, Mount Etjo Safari Lodge, was where I heard Nossi's story. Nossi, a black rhino, was born in Etosha National Park, a place where my parents and I spent many holidays when I was young. When Nossi was born, her mother was stressed and pushed her around. By the time the vet arrived, Nossi only had a 10% chance of survival. With massive investment of time, energy and care, Nossi survived and, last year, she gave birth to her eighth child. In a population in danger of extinction, this represents an important increase in the world's black rhino population. All of these efforts have paid off and I learned that my support matters. Your support matters too. Because together, we can save the rhino. Together, it is likely that we can change the world.