Caro et al. (2022) assert that there is an “inconvenient misconception” in conservation biology that climate change poses a significant risk to biodiversity. They support their claim with suggestions that climate change has not been a major recorded driver of species extinctions since 1900 and has not been reported as a key driver in IUCN threat analyses. However, given the accelerating and nonlinear nature of climate change impacts, we argue that the recent past is not a reliable guide to future change, and that conservation must look to the future if it is to successfully anticipate and mitigate biodiversity loss.

The latest IPCC Working Group II report states that up to 14% of species will face a very high risk of extinction at 1.5°C of heating, rising to up to 29% at 3°C. Such temperature increases are worryingly imminent, with the 1.5°C threshold expected to be passed within decades, and 3°C anticipated within the century given current emissions trajectories (IPCC, 2022). In those biodiversity hotspots classed as vulnerable, 2°C of climate change is expected to double the number of species at very high risk of extinction, and by 3°C the risk is expected to be an order of magnitude larger than at present (IPCC, 2022). The scale of the threat shocked even the report's authors, with one remarking that; “One of the most striking conclusions in our report is that we're seeing adverse impacts that are much more widespread and much more negative than expected” (Plummer & Zhong, 2022).

Caro et al.’s focus on the decline and extinction of individual species, while easier to quantify, masks the more pervasive and critical impacts climate change can have on ecosystems; most species in any ecosystem are adapted to similar abiotic conditions, thus climatic change will stress most species simultaneously, undermining the resilience of the system and increasing the potential for dramatically nonlinear changes in its structure and function. These rapid changes may lead to the simultaneous losses of whole communities of species (Trisos et al., 2020). For example, tropical warm water corals are estimated to support at least 25% of known marine species, but anthropogenic global warming has already led to a >20-fold increase in marine heat waves, resulting in bleaching which risks not only the loss of corals but the species reliant on these ecosystem engineers (Hoegh-Guldberg et al., 2017). Australia's Great Barrier Reef has already lost half its coral cover within just the last three decades (Dietzel et al., 2020). The potential for such rapid ecosystem-wide changes is not restricted to aquatic ecosystems; substantial parts of the Amazon rainforest are rapidly losing resilience due to a combination of warming-induced drought and expanding deforestation, pushing the system toward a tipping point beyond which fire will create a savannah-like ecosystem, leading to a catastrophic loss of forest-obligate wildlife (Boulton et al., 2022).

Clearly, climate change has the potential to severely damage biodiversity, both in isolation and in combination with other anthropogenic threats, emphasizing the need to proactively manage ecosystems to protect them from the multifaceted nature of future global change. Indeed, failure to do so threatens the resilience of human societies and natural systems (Pörtner et al., 2021). While assessing past biodiversity loss can help evidence the negative impacts humanity has on the global biosphere, the past is a poor guide for where we are headed. Fixating on retrospective analyses as a predictor of future trends in a world characterized by increasingly rapid environmental change risks catastrophically underestimating future biodiversity loss (Gardner & Bullock, 2021) and is unnecessary when robust predictive approaches are available (see e.g., Trisos et al., 2020 and work synthesized in IPCC, 2022). Of particular importance is understanding how a rapidly changing climate will interact with other drivers of biodiversity decline such as habitat fragmentation and overexploitation of populations (Brook et al., 2008). Conservation science must quickly orient itself toward the oncoming threats we face.

卡罗等。( 2022 ) 声称在保护生物学中存在一个“不便的误解”，即气候变化对生物多样性构成重大风险。他们支持自己的主张，并建议气候变化自 1900 年以来并不是物种灭绝的主要记录驱动因素，也没有被报告为 IUCN 威胁分析中的关键驱动因素。然而，鉴于气候变化影响的加速和非线性性质，我们认为最近的过去并不是未来变化的可靠指南，如果要成功预测和减轻生物多样性的丧失，保护工作必须着眼于未来。

最新的 IPCC 第二工作组报告指出，在升温 1.5°C 时，多达 14% 的物种将面临极高的灭绝风险，在升温 3°C 时，这一数字将上升至 29%。令人担忧的是，这种温度升高迫在眉睫，预计将在几十年内超过 1.5°C 的阈值，根据当前的排放轨迹，预计将在本世纪内超过 3°C（IPCC，2022）。在那些被列为脆弱的生物多样性热点地区，气候变化 2°C 预计将使面临灭绝风险的物种数量增加一倍，而 3°C 预计风险将比目前大一个数量级（IPCC , 2022 年）。威胁的规模甚至令该报告的作者感到震惊，其中一位评论说；“我们报告中最引人注目的结论之一是，我们看到的不利影响比预期的更广泛、更负面”（Plummer & Zhong，2022 年）。

Caro 等人关注单个物种的衰退和灭绝，虽然更容易量化，但掩盖了气候变化可能对生态系统产生的更普遍和关键的影响；任何生态系统中的大多数物种都适应类似的非生物条件，因此气候变化将同时对大多数物种造成压力，破坏系统的复原力并增加其结构和功能发生显着非线性变化的可能性。这些快速变化可能导致整个物种群落同时消失（Trisos 等人，2020 年）). 例如，据估计，热带温水珊瑚至少支持 25% 的已知海洋物种，但人为全球变暖已经导致海洋热浪增加 20 倍以上，导致白化，这不仅有珊瑚损失的风险但物种依赖于这些生态系统工程师（Hoegh-Guldberg 等人，2017 年）。澳大利亚的大堡礁在过去三十年内已经失去了一半的珊瑚覆盖（Dietzel 等人，2020). 这种全生态系统快速变化的潜力不仅限于水生生态系统；由于变暖引起的干旱和不断扩大的森林砍伐，亚马逊雨林的大部分地区正在迅速失去恢复力，将系统推向一个临界点，超过该临界点，火灾将创造一个类似大草原的生态系统，导致森林专性的灾难性损失野生动物（Boulton 等人，2022 年）。

显然，气候变化有可能单独或与其他人为威胁一起严重破坏生物多样性，强调需要主动管理生态系统以保护它们免受未来全球变化的多方面影响。事实上，如果不这样做，就会威胁到人类社会和自然系统的复原力（Pörtner 等人，2021 年）。虽然评估过去的生物多样性丧失有助于证明人类对全球生物圈的负面影响，但过去并不能很好地指导我们前进的方向。在一个以日益迅速的环境变化为特征的世界中，将回顾性分析作为未来趋势的预测指标可能会灾难性地低估未来生物多样性的丧失（Gardner & Bullock，2021 年）) 并且当有可靠的预测方法可用时是不必要的（参见例如，Trisos 等人，2020 年和 IPCC 综合工作，2022 年）。尤其重要的是了解快速变化的气候将如何与生物多样性下降的其他驱动因素相互作用，例如栖息地破碎化和种群过度开发（Brook 等人，2008 年）。保护科学必须迅速将自己定位于我们面临的即将到来的威胁。