It's since 1980, they've had almost half a century to do it.

Just a matter of scale. Every seventh person lives in China.

Or to recontextualize: The article talks about a time span of around 45 years. That's around 1.7 billion trees. Remember, that's an english (short) billion, 1700 million. (In other languages a billion is a million millions, and not just a thousand millions.)

If a worker can plant 20 trees a day and works 200 days a year, that means around half a million people are more than enough to do it. In a country with around 1400 million people, that's 0.035% of the population, or roughly one in 3000 people.

Suddenly, it's not all that crazy anymore.

In Estonia we plant about 20-40 millions of trees every year.

RMK ( State Forest Management Center) alone plants about 20-25 million trees every year.

And we are nation with 1,3 million people. So for China that number over the years isn’t big at all.

I always laugh when in the western news there is some organization, what makes big words that they planted 2 million trees and if that is something of a big achivments what should be boasted around the news.

Yes, I was shocked too. But in 1949 apparently 8.6% of the country was forested; in 2022 it was 24%.

In 2005 they launched the "Greening China" initiative to plant 13 Trillion (yes Trillion with a T) trees in 10 years. They didn't succeed but in 2021 the People's Daily claimed 78.1bn trees planted in 40 years Link.

However - China is known for inflating statistics to suit the communist party's own ends, and the People's Daily is part of the country's propaganda system. It's probably far less than 78bn, and that figure doesn't count replants and commerically logged trees. But it seems that whatever the figure there really has been a concerted long term reforestation effort in China.