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Large‐scale reforestation can potentially bring both benefits and risks to the water cycle, which needs to be better quantified under future climates to inform reforestation decisions. We identified 477 water‐insecure basins worldwide accounting for 44.6% (380.2 Mha) of the global reforestation potential. As many of these basins are in the Asia‐Pacific, we used regional coupled land‐climate modeling for the period 2041–2070 to reveal that reforestation increases evapotranspiration and precipitation for most water‐insecure regions over the Asia‐Pacific. This resulted in a statistically significant increase in water yield (p <.05) for the Loess Plateau–North China Plain, Yangtze Plain, Southeast China, and Irrawaddy regions. Precipitation feedback was influenced by the degree of initial moisture limitation affecting soil moisture response and thus evapotranspiration, as well as precipitation advection from other reforested regions and moisture transport away from the local region. Reforestation also reduces the probability of extremely dry months in most of the water‐insecure regions. However, some regions experience nonsignificant declines in net water yield due to heightened evapotranspiration outstripping increases in precipitation, or declines in soil moisture and advected precipitation. [ABSTRACT FROM AUTHOR]

Protected areas (including other effective area-based conservation measures) are a cornerstone of biodiversity conservation. Many countries are increasingly committed to expanding protected area coverage to 30%, which requires an increase in global annual spending from $24b to ~$140b (between $103b and $177b). We find that by trading nature-based carbon credits in voluntary carbon markets at the current average market price of $5 t−1CO 2 , 79 countries and territories can expand protected areas without capital deficit, together generate return on investments of $121b yr−1 and sequester 3 GtCO 2 eyr−1. Another 30 countries can meet at least half of their investment costs, and sequester an additional 2.8 GtCO 2 e yr−1. Additionally, we show that protection can extend to 33% of the Key Biodiversity Areas (KBAs) outside the existing protected area network. Our results point to the largely untapped potential of nature-based climate solutions to accelerate protected area expansion, thereby conserving biodiversity and mitigating climate change. [ABSTRACT FROM AUTHOR]