At the time of this writing, the coronavirus pandemic has the attention of the entire world. It has been aptly referred by many scientists as the ultimate Black Swan event; that is to say, an extremely surprising random occurrence that is having a huge impact on the world economy and that experts try to explain away as something that was predictable, if only we had had the imagination to foresee it.

The rapid spread of the virus to all corners of the globe, the number of infections, and the death toll are beyond belief in a world that unwittingly celebrated the beginning of a new decade just a few months ago. This global health emergency reminds us that we live in a deeply interconnected world. It focuses our attention on the most vulnerable in society, on the need for global cooperation, and on the importance of professional leadership and expertise.

Sound familiar? Coronavirus disease 2019 (COVID‐19) is preceded by several environment and health emergencies that we felt, at that time, would also remind us of a shared humanity, our inseparable connection to the environment, and the need for unity. Perhaps most prominent prior to the emergence of the coronavirus were the alarms sounding about the pervasive presence of plastic debris in our oceans, microplastics in the food chain and consumed by people, and the widespread use of the newly designated class of forever chemicals called per‐ and polyfluoroalkyl substances (PFAS). In fact, these are the latest in a long list of emergencies and calls for action dating back to recognition in the 1960s of the dangers posed by DDT and pesticides and, thereafter, by Hg, PCBs, dioxins, and flame retardant substances.

In hindsight, each time our response has been predictable. Shock and horror are soon replaced by laying blame and finger pointing, filing lawsuits (certainly true in the United States), and regulatory bans. With respect to chemical hazards, early reactions reflect our concerns for public health and as time passes migrate to the possible consequences for the environment and for wildlife. Scientific studies are commissioned, investigation methods are devised, and work is conducted around the world. The results arrive, and scientific and legal arguments ensue, claiming bias in the study methods, analysis, and interpretation of the data used to support certain points of view. Meanwhile, the onslaught of laboratory experiments and environmental monitoring continues, taking full advantage of the sudden availability of financial resources and opportunities to claim leadership and capture the public's worried attention. Concurrent with this sequence of events is the deluge of papers submitted to scientific review panels and technical journals for peer review where the information is debated and more often than not found to be incomplete and requiring further investigation. The cause of the crisis is rarely understood. The scientific process takes years to clarify and at a snail's pace; all the while politicians formulate regulatory policy and move forward to appease a panicked public.

And, so it goes…until the next Black Swan event.

Society should be increasingly immune to surprise by Black Swans. The ability to predict the consequences of human activities and technological inventions—both chemical and mechanical—have improved immensely during our professional lives. Scientists understand well the consequences of human intervention in nature and subsequent cause‐and‐effect relationships. This has been our life's work.

Should we have been surprised that halogens bound to aromatic rings are persistent and resistant to degradation? That materials with high logP values bioaccumulate or biomagnify? Should we have been caught unawares that volatile materials are transported by the atmosphere for long distances? If materials are made resistant to chemical, temperature, or biological degradation, then should we be surprised to find those same materials in our drinking water, soil, sediment, or biota? Chemical structures and structure–activity relationships are well understood; so should we not be surprised, for example, when certain substances behave as predicted and affect metabolic pathways or disrupt endocrine functions?

The scientific process takes years to clarify and at a snail's pace; all the while politicians formulate regulatory policy and move forward to appease a panicked public.

The fundamental question society faces today, and most certainly the scientific community, as a consequence of the ongoing coronavirus pandemic, is not whether we have sufficient knowledge of the fate and effects of chemicals or plastics or even viruses on the environment and human health; it is whether we are able to connect scientific observation and theoretical study to real‐life consequences.

We appear to suffer from a grand “not‐in‐my‐backyard” attitude, wherein we have a void in our imaginations and ingenuity that inhibits our ability to translate science safely to the function and enjoyment of our daily lives. We simply do not have sufficient knowledge of our place in nature or control of our imaginations to foresee consequences, ask key questions, and to put a process in place. Can it be that we fundamentally misunderstand cause and effect?

Pearl and Mackenzie (2018) describes 3 levels on the ladder of causation. The ladder is a metaphor for understanding potential realities. The lowest step of the ladder is what he calls “seeing,” that is, observing how variables may be associated. In statistics this level corresponds to observing associations. And although the late Peter Chapman would gladly remind us all that “association is not causation,” associations can suggest places to investigate. The second step of the ladder is “intervention.” Experiments are interventions; the classic before‐and‐after control field design is another excellent case. However, experiments may lead to an understanding that after x , then y occurs, but not lead to the understanding of the mechanism. It is not the why or how question that is key to predicting a previously unrecognized or unobserved event.

The third step of Pearl's causation ladder is perhaps the rung scientists rarely step upon. It is labeled “counterfactual.” Here we must ask “what if” and “so what” questions. We must imagine new situations and retrospectively examine prior experiments and experiences to gain insight into causal mechanisms. An understanding of mechanisms helps us to explore more critical questions. For example, when Hooper et al. (2013) ask how climate change affects biochemical pathways that regulate toxicity, Carriger and Barron (2011) imagine a variety of scenarios and the effects of different management options to mitigate the possibility for enhancing toxicity. Graham et al. (2019) imagine even larger scale consequences for an entire region of the continent of Australia. And by so imagining, we collectively avoid Black Swans.

Are we enlightened by the current events of COVID‐19 and are we likely to witness another global pandemic of biological or chemical origin in the future? Most certainly, on both accounts. Scientists need to be better at imagining new conditions, unexpected observations, assimilating experimental and field research into a series of mechanistic questions. Scientists need to have an investigatory and management plan for plausible Black Swans. Then when such an event occurs, it may have already been imagined and we have a process to understand the observation. For now, current events are an opportunity for discovery and to devise a strategic viewpoint, a careful process, and clear reporting.

在撰写本文时，冠状病毒大流行引起了全世界的关注。许多科学家恰当地将其称为终极黑天鹅事件。也就是说，这是一个非常令人惊讶的随机事件，它对世界经济产生了巨大影响，并且如果我们只有想象力，专家会尝试将其解释为可预测的事物。

病毒在几个月前无意中庆祝了一个新的十年的开始，这一病毒迅速传播到全球各个角落，感染数量和死亡人数令人难以置信。这次全球卫生突发事件提醒我们，我们生活在一个相互联系的世界中。它将我们的注意力集中在社会上最弱势的人群，全球合作的需要以及专业领导和专业知识的重要性上。

听起来有点熟？在2019年冠状病毒疾病（COVID-19）发生之前，我们当时曾感觉到一些环境和健康紧急情况，这也使我们想起了人类共有，与环境密不可分的联系以及团结的需要。冠状病毒出现之前最突出的可能是以下警报：我们的海洋中普遍存在塑料碎片，食物链中的微塑料以及人们食用的塑料，以及新指定的永久性化学品类别per-per的广泛使用和多氟烷基物质（PFAS）。实际上，这些是一长串紧急事件中的最新事件，并呼吁采取行动，最早可追溯到1960年代，认识到滴滴涕和杀虫剂以及汞，多氯联苯，二恶英和阻燃剂造成的危险。

事后看来，每次我们的反应都是可以预测的。震惊和恐怖很快被指责和指责，提起诉讼（在美国某些情况下确实如此）和监管禁令所取代。关于化学危害，早期反应反映了我们对公共健康的关注，随着时间的流逝，迁移到对环境和野生生物可能造成的后果。委托科学研究，设计调查方法，并在世界各地开展工作。结果到来，随之而来的是科学和法律上的争论，声称研究方法，分析和用于支持某些观点的数据的解释存在偏见。同时，实验室实验和环境监测的冲击仍在继续，充分利用突然可用的财务资源和机会来争取领导权并吸引公众的担忧。与这一系列事件同时发生的是，有大量论文提交给科学审查小组和技术期刊以供同行审查，在这些文献中，人们对信息进行辩论，并且经常发现信息不完整，需要进一步调查。危机的原因鲜为人知。科学过程需要花费数年的时间才能弄清楚并达到蜗牛的步伐。政客们一直在制定监管政策，并继续安抚惊慌的公众。与这一系列事件同时发生的是，有大量论文提交给科学审查小组和技术期刊以供同行审查，在这些文献中，人们对信息进行辩论，并且经常发现信息不完整，需要进一步调查。危机的原因鲜为人知。科学过程需要花费数年的时间才能弄清楚并达到蜗牛的步伐。政客们一直在制定监管政策，并继续安抚惊慌的公众。与这一系列事件同时发生的是，有大量论文提交给科学审查小组和技术期刊以供同行审查，在这些文献中，人们对信息进行辩论，并且经常发现信息不完整，需要进一步调查。危机的原因鲜为人知。科学过程需要花费数年的时间才能弄清楚并达到蜗牛的步伐。政客们一直在制定监管政策，并继续安抚惊慌的公众。

顺便说一句，直到下一次黑天鹅比赛。

社会应该越来越不受黑天鹅的惊讶。在我们的职业生涯中，预测人类活动和技术发明（包括化学和机械）后果的能力已大大提高。科学家们非常了解人为干预自然的后果以及随后的因果关系。这是我们一生的工作。

我们是否应该对与芳香环键合的卤素持久且抗降解感到惊讶？具有高logP值的材料会生物积聚或生物放大吗？难道我们不应该意识到挥发性物质是由大气远距离传输的吗？如果使材料具有抗化学，温度或生物降解的能力，那么我们是否应该惊讶于在饮用水，土壤，沉积物或生物区系中找到相同的材料？化学结构和结构-活性关系是众所周知的。因此，例如某些物质的行为达到预期并影响代谢途径或破坏内分泌功能时，我们是否应该感到惊讶？

科学过程需要花费数年的时间才能弄清楚并达到蜗牛的步伐。政客们一直在制定监管政策，并继续安抚惊慌的公众。

当今社会所面临的根本问题，以及由于冠状病毒大流行所导致的科学界，当然最不能肯定的是，我们是否对化学药品或塑料甚至病毒对环境和人类健康的命运和影响没有足够的了解；这是我们是否能够将科学观察和理论研究与现实生活的后果联系起来。

我们似乎遭受了一种宏伟的“不在我家后院”的态度，其中我们的想象力和独创性都存在空白，这限制了我们将科学安全地转化为日常生活的功能和乐趣的能力。我们根本没有足够的知识来了解我们在自然界中的位置，也没有控制我们的想象力来预见后果，提出关键问题并制定流程。难道是我们从根本上误解了因果关系吗？

Pearl和Mackenzie（2018）在因果关系阶梯上描述了3个层次。阶梯是理解潜在现实的隐喻。阶梯的最低步骤是他所谓的“观察”，即观察变量如何关联。在统计中，此级别对应于观察关联。尽管已故的彼得·查普曼（Peter Chapman）很乐意提醒我们所有人“协会不是因果关系”，但协会可以建议调查的地方。阶梯的第二步是“干预”。实验是干预；经典的前后控制场设计是另一个很好的例子。但是，实验可能会导致我们理解，在x之后，则y发生，但没有导致对机制的理解。这不是为什么或如何成为预测先前无法识别或无法观察事件的关键。

Pearl的因果关系阶梯的第三步也许是梯级科学家们很少采取的措施。它被标记为“反事实”。在这里，我们必须问“如果”和“怎么”的问题。我们必须想象新的情况，并回顾性地检查以前的实验和经验，以了解因果机制。对机制的理解有助于我们探索更多关键问题。例如，当胡珀等。（2013年）询问气候变化如何影响调节毒性的生化途径，Carriger和Barron（2011年）设想了各种情况以及不同管理方案的影响，以减轻增强毒性的可能性。Graham等。（2019）想象一下，对澳大利亚大陆整个地区的大规模后果。通过这样的想象，我们共同避免了“黑天鹅”。

我们是否对COVID-19的当前事件感到高兴，并且将来是否有可能目睹另一场全球性的生物或化学大流行？最肯定的是，在两个方面。科学家需要更好地想象新的条件，意想不到的观察结果，并将实验和现场研究纳入一系列机械问题。科学家需要为可能的黑天鹅制定调查和管理计划。然后，当发生此类事件时，可能已经想像得到了，我们有了一个过程来了解观察结果。就目前而言，时事是一个发现和制定战略观点，谨慎流程和清晰报告的机会。