Current and near future climate policy will fundamentally influence the integrity of ecological systems. The Neotropics is a region where biodiversity is notably high and precipitation regimes largely determine the ecology of most organisms. We modeled possible changes in the severity of seasonal aridity by 2100 throughout the Neotropics and used birds to illustrate the implications of contrasting climate scenarios for the region's biodiversity. Under SSP‐8.5, a pessimistic and hopefully unlikely scenario, longer dry seasons (> 5%), and increased moisture stress are projected for about 75% of extant lowland forests throughout the entire region with impacts on 66% of the region's lowland forest avifauna, which comprises over 3000 species and about 30% of all bird species globally. Longer dry seasons are predicted to be especially significant in the Caribbean, Upper South America, and Amazonia. In contrast, under SSP‐2.6—a scenario with significant climate mitigation—only about 10% of the entire region's forest area and 3% of its avifauna will be exposed to longer dry seasons. The extent of current forest cover that may plausibly function as precipitation‐based climate refugia (i.e., < 5% change in length of dry periods) for constituent biodiversity is over 4 times greater under SSP‐2.6 than with SSP‐8.5. Moreover, the proportion of currently protected areas that overlap putative refugia areas is nearly 4 times greater under SSP‐2.6. Taken together, our results illustrate that climate policy will have profound outcomes for biodiversity throughout the Neotropics—even in areas where deforestation and other immediate threats are not currently in play.

中文翻译：

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不同排放情景下新热带森林鸟类及其栖息地的前景


当前和不久的将来的气候政策将从根本上影响生态系统的完整性。新热带地区是一个生物多样性非常高的地区，降水状况在很大程度上决定了大多数生物的生态学。我们模拟了到 2100 年整个新热带地区季节性干旱严重程度的可能变化，并使用鸟类来说明对比气候情景对该地区生物多样性的影响。在SSP-8.5下，预计整个地区约75%的现存低地森林将出现悲观且希望不太可能的情况，旱季延长（> 5%）和水分胁迫增加，影响该地区66%的低地森林鸟类，其中包括3000多个物种和全球所有鸟类的约30%。预计加勒比地区、上南美洲和亚马逊地区的旱季延长尤为明显。相比之下，在 SSP-2.6（一种具有显著气候缓解作用的情景）下，整个地区只有约 10% 的森林面积和 3% 的鸟类将面临更长的旱季。目前森林覆盖的范围可能作为基于降水的气候避难所（即 < 干旱期长度变化 5%），在 SSP-2.6 下比在 SSP-8.5 下大 4 倍以上。此外，在 SSP-2.6 下，目前保护区与假定的避难所区域重叠的比例几乎高出 4 倍。综上所述，我们的结果表明，气候政策将对整个新热带地区的生物多样性产生深远影响，即使在目前没有森林砍伐和其他直接威胁的地区也是如此。