Beijing has intensified decadeslong efforts to plant billions of trees across the country, especially in northern areas threatened by growing deserts. Every year, it plants seedlings over an area equal to Ireland. The state has pledged to boost forest coverage to 30% by 2050. Today, World Bank data say it's about 22%. But critics say non-native species and monocultures threaten water resources.

China has also taken its expertise abroad. In Iraq, limited rain, dropping water levels, increasingly high temperatures and the volatile security situation have exacerbated desertification. Inspired by Chinese techniques, like one that uses a grid of straw squares to hold the ground together and provide a base for grasses and eventually, larger plants, experts hope to hold back the dunes.

In Africa's Sahel region, south of the Sahara, they've taken a different approach. With a variety of local vegetation and a technique that grows trees from existing root systems, local farmers have helped regreen 50,000 square kilometers (19,300 square miles) in Niger alone. This technique, developed by Australian agronomist Tony Rinaudo, was recognized with the Right Livelihood Award in 2018.

In neighboring Burkina Faso, the UN program REDD+ helps farmers launch a large-scale tree planting effort of over 300,000 hectares (740,000 acres) to help mitigate desertification. Forests here are threatened due to expanding farms and a growing population, one of Africa's fastest. REDD+, launched in 2008, works with indigenous peoples in 65 countries in Africa, Asia-Pacific and Latin America.

In a country where nearly 30% of the land is degraded — by farming, urbanization and deforestation —tree planting efforts are major events. In recent years millions of Indians have joined record-breaking campaigns, planting hundreds of millions of seedling. About 40% succumb to disease or lack of water. The Modi government has pledged to restore 26 million hectares of degraded land by 2030.

The Amazon rainforest is under threat from cattle ranching and resource extraction, not to mention the devastating fires in 2019. Deforestation in Brazil rose to its highest level in over a decade last year. In neighboring Peru, reforestation efforts have targeted fields damaged by illegal gold mining, as well as the Machu Picchu archaeological site, which is at risk of mudslides and forest fires.

Australia has been ravaged by bushfires, which wiped out more than a fifth of its forests and killed some 1 billion animals. In December, the World Wide Fund for Nature launched a plan to "save and grow" 2 billion trees by 2030. "This natural climate solution can be achieved by protecting existing trees, allowing cleared forests to regenerate and planting new trees," said WWF — a boon for koalas.

A tree planting veteran, Canada has been reforesting for decades — on private and public land,where laws require the forestry industry to replant following clearcutting. In his 2019 election campaign, Prime Minister Justin Trudeau committed to adding 2 billion trees over the next decade. A wide range of biomes, from Arctic tundra to temperate rainforest, makes tree selection important.

In northern England, trees cover just 7.6% of the countryside. But a new Northern Forest is set to take shape from western Liverpool to eastern Hull over the next 25 years. It follows the success of the National Forest further south, which saw its first saplings in 1995. It's hoped more trees will help ease climate change, reduce flooding and create jobs. But critics say it's mere greenwashing.

The forests that inspired legends and fairy tales aren't doing so well. At a national forest summit last September, Berlin devoted €800 million ($878 million) to help care for and replenish the country's trees, which have suffered from several years of hot, dry weather and bark beetle attacks. Forestry experts are searching for hardy, native species which can adapt to Europe's changing climate.

Widespread illegal logging — some sourced to timber firms and furniture makers in Western Europe — is devastating some of Europe's last remaining virgin forests. Romania loses about 3-9 hectares (7-22 acres) of forest per hour to dishonest timber firms, according to Greenpeace. In early 2020, the Environment Ministry announced plans to replant more than 1,000 hectares of these affected forests.