The Ethiopian government has announced a truly extraordinary record, claiming the nation’s citizens planted 353 million trees in 12 hours, beating a 200 million tree target. The previous record for a single country was 66 million, by India, a nation three times as large with 13 times the population.

Earlier this month a paper in Science offered a rare glimmer of climate hope. The authors used satellite data of canopy coverage and soil maps to calculate the Earth has 9 million square kilometers (3.5 million square miles) of land suited to being planted with trees and not currently forested, urban or used for crops. Once grown, these trees would store 205 billion tonnes (225 billion tons) of carbon, two-thirds of the carbon humans have released since the Industrial Revolution.

So how does Ethiopia’s effort stack up? The carbon storage potential of trees varies enormously by species of course, as well as the conditions in which they are grown. The Science paper estimated, however, that it would take 500 billion trees to cover the proposed area. Assuming an (optimistic) 50 percent survival rate for the planted seedlings, the world needs to repeat this feat almost 3,000 times.

The project had local motivations as well, however. An environmental census a few years ago reported just 4 percent of Ethiopia was covered by forest. At the start of the 20th century, it was 35 percent. That loss has contributed to erosion and desertification, made droughts and floods more extreme and deprived threatened species of habitat. Deforestation contributed to the horrendous famine of the 1980s.

Ethiopia has experienced some of the most rapid economic benefits in recent years, as well as making progress on human rights, but ethnic tensions have risen with close to a million people fleeing their homes for fear of violence. It is hoped widespread participation in the planting program will give Ethiopians a common purpose. The government has set a target of 4 billion trees planted this season, and claims to have already reached more than half of that goal.

Even 9 million square kilometers of tree cover is no get out of jail free card for climate catastrophe. If we keep burning fossil fuels at the current rate we will undo all that good in 22 years. Moreover, the paper noted it takes decades to centuries for trees to reach their full storage capacity, and higher temperatures will make some of the identified areas unsuitable for supporting trees.

On our current trajectory a quarter of the identified areas will be unable to support trees by 2050, so we need to get started with both the planting and emissions reduction fast. In particular, the 3 trillion existing trees will need to be preserved from the rampant deforestation still underway in many regions. Ethiopia has thrown down the challenge.