Land aridification persists in vulnerable drylands under climate mitigation scenarios

Understanding how climate systems respond to carbon dioxide removal is crucial for assessing effectiveness of carbon neutrality policies. Here we show that rising carbon dioxide intensifies aridity over vast regions, particularly in vulnerable and climate-sensitive drylands based on idealized emission-driven simulations from an Earth System Model. Notably, even as carbon dioxide concentrations decline, arid regions continue to expand and experience worsening conditions, exacerbating climate injustice and resource conflicts. This pronounced hysteresis is primarily driven by long-lasting precipitation reductions in the tropics, linked to hysteresis of the intertropical convergence zone. The asymmetric response of arid zones suggests that reversing aridity intensification under global warming is exceptionally difficult. Further analysis highlights that negative carbon dioxide emissions may be essential to mitigating these deteriorating conditions, yet full recovery requires extended timescales. Our findings underscore irreversible risks of delayed action and stress the urgent need for carbon neutrality strategies that go beyond net-zero targets. Drylands continue to expand and experience increasingly harsh conditions even as carbon dioxide emissions decline, but negative emissions may be essential to mitigating aridity, albeit on a longer timescale, according to an analysis of idealized emissions-driven climate model simulations.