aridity

More than three-quarters of the earth's land surface experienced drier climates between 1990 and 2020 compared to the previous three decades, according to a new report by the United Nations Convention to Combat Desertification. Over the past 30 years, 40.6 percent of the global landmass, excluding Antarctica, is classified as drylands, three percentage points more than the previous three decades. The report, which is being presented at the COP16 on desertification being held in Riyadh, Saudi Arabia, also shows that 2.3 billion people were living in drylands in 2020, a population that could rise to 5 billion by 2100 under a worst-case climate change scenario.

A study published in Science analyses the potential climate benefits of afforestation - both planting trees to create new forests and reforesting old ones - of the world's drylands. The authors show that the cooling effect of afforestation of this vast area would only amount to a decrease of about 1 % of projected greenhouse gas emissions in the business-as-usual and medium-emissions climate scenarios.