Drylands cover 41% of Earth’s surface and are the largest source of interannual variability in the global carbon sink. Drylands are projected to experience accelerated expansion over the next century, but the implications of this expansion on variability in gross primary production (GPP) remain elusive. Here we show that by 2100 total dryland GPP will increase by 12 ± 3% relative to the 2000–2014 baseline. Because drylands will largely expand into formerly productive ecosystems, this increase in dryland GPP may not increase global GPP. Further, GPP per unit dryland area will decrease as degradation of historical drylands outpaces the higher GPP of expanded drylands. Dryland expansion and climate-induced conversions among sub-humid, semi-arid, arid, and hyper-arid subtypes will lead to substantial changes in regional and subtype contributions to global dryland GPP variability. Our results highlight the vulnerability of dryland subtypes to more frequent and severe climate extremes and suggest that regional variations will require different mitigation strategies.

旱地面积占地球表面的41％，是全球碳汇中年际变化的最大来源。预计旱地将在下一世纪经历加速扩张，但是这种扩张对初级生产总值（GPP）变异性的影响仍然难以捉摸。在这里，我们显示到2100年，相对于2000-2014年基线，旱地总GPP将增长12±3％。由于旱地将在很大程度上扩展为以前的生产生态系统，因此旱地GPP的增加可能不会增加全球GPP。此外，每单位旱地面积的GPP会降低，因为历史旱地的退化速度超过了扩展旱地的较高GPP。干旱地区，半干旱，半干旱，干旱，超干旱亚型将导致区域和亚型对全球旱地GPP变异性的贡献发生重大变化。我们的结果凸显了旱地亚型在更频繁和严重的极端气候中的脆弱性，并表明区域差异将需要不同的缓解策略。