"Results showed that carbon dioxide fertilization explains 70 percent of the greening effect, said co-author Ranga Myneni, a professor in the Department of Earth and Environment at Boston University. “The second most important driver is nitrogen, at 9 percent. "
https://www.nasa.gov/feature/goddard/2016/carbon-dioxide-fer...
The greening is also observed in areas unaffected by man's agricultural activities.
>The researchers point out that the gain in greenness seen around the world and dominated by India and China does not offset the damage from loss of natural vegetation in tropical regions, such as Brazil and Indonesia. The consequences for sustainability and biodiversity in those ecosystems remain.
Thinking that China and India have "got this" would be a catastrophic assumption (obligatory xkcd[0]).
[0] - https://xkcd.com/1732/
What is truly new, is that human activity in India and China alone is responsable of a 16% increase of leaf area. So, to quote original article:
> now that we know direct human influence is a key driver of the greening Earth, we need to factor this into our climate models
[0] https://climate.nasa.gov/news/2436/co2-is-making-earth-green...
[1] https://www.nasa.gov/feature/ames/human-activity-in-china-an...