We are deeply disturbed by the recent escalation of political assaults on scientists in general and on climate scientists in particular. All citizens should understand some basic scientific facts. There is always some uncertainty associated with scientific conclusions; science never absolutely proves anything. When someone says that society should wait until scientists are absolutely certain before taking any action, it is the same as saying society should never take action. For a problem as potentially catastrophic as climate change, taking no action poses a dangerous risk for our planet.
Scientific conclusions derive from an understanding of basic laws supported by laboratory experiments, observations of nature, and mathematical and computer modelling. Like all human beings, scientists make mistakes, but the scientific process is designed to find and correct them. This process is inherently adversarial— scientists build reputations and gain recognition not only for supporting conventional wisdom, but even more so for demonstrating that the scientific consensus is wrong and that there is a better explanation. That’s what Galileo, Pasteur, Darwin, and Einstein did. But when some conclusions have been thoroughly and deeply tested, questioned, and examined, they gain the status of “well-established theories” and are often spoken of as “facts.”
科学结论来自于经过实验室实验、 自然观察以及数学和电脑模式运算所支持的基本定律的理解，就像所有人类一样，科学家会犯错，但是科学过程的设计可以发掘并修正错误，这个过程本质就是有一 点争辩与对立的—科学家建立声誉获得认同不仅来自于对传统智慧的诠释，更来自于举出原有科学想法的错误并提出更好的解释，就像加利略、巴斯德、达尔文和爱 因斯坦等所作的一样，当部分科学结论经过全面且深入的测试、质疑和检验，这些科学结论就会被视为”已建立的理论”(well-established theories)也就成为我们所说的”事实”。
For instance, there is compelling scientific evidence that our planet is about 4.5bn years old (the theory of the origin of Earth), that our universe was born from a single event about 14bn years ago (the Big Bang theory), and that today’s organisms evolved from ones living in the past (the theory of evolution). Even as these are overwhelmingly accepted by the scientific community, fame still awaits anyone who could show these theories to be wrong. Climate change now falls into this category: there is compelling, comprehensive, and consistent objective evidence that humans are changing the climate in ways that threaten our societies and the ecosystems on which we depend.
Many recent assaults on climate science and, more disturbingly, on climate scientists by climate change deniers, are typically driven by special interests or dogma, not by an honest effort to provide an alternative theory that credibly satisfies the evidence. The Intergovernmental Panel on Climate Change (IPCC) and other scientific assessments of climate change, which involve thousands of scientists producing massive and comprehensive reports, have, quite expectedly and normally, made some mistakes. When errors are pointed out, they are corrected. But there is nothing remotely identified in the recent events that changes the fundamental conclusions about climate change:
反对气候变迁论者最近对于气候科学或更令人不以为意地对气候科学家的许多攻击，是基于特殊的利害关係和某些基本教义，并不是以诚实的方式提出另一种理论，确实可以找到证据加以有效地验证，政府间气候变迁委员会（Intergovernmental Panel on Climate Change, IPCC）和其他有关气候变迁的科学评估，即使是透过成千科学家大量和全面地彙整现有的科学报告，其中仍然还是有些错误，这是十分可预期和正常的，但是当误差被指出，就立刻会被科学社群加以检验改正，到目前也没有任何最近的事件被证明可以改变气候变迁的基本结论：
(i) The planet is warming due to increased concentrations of heat-trapping gases in our atmosphere. A snowy winter in Washington does not alter this fact.
(ii) Most of the increase in the concentration of these gases over the last century is due to human activities, especially the burning of fossil fuels and deforestation.
(iii) Natural causes always play a role in changing Earth’s climate, but are now being overwhelmed by human-induced changes.
(iv) Warming the planet will cause many other climatic patterns to change at speeds unprecedented in modern times, including increasing rates of sea-level rise and alterations in the hydrologic cycle. Rising concentrations of carbon dioxide are making the oceans more acidic.
(v) The combination of these complex climate changes threatens coastal communities and cities, our food and water supplies, marine and freshwater ecosystems, forests, high mountain environments, and far more.
Much more can be, and has been, said by the world’s scientific societies, national academies, and individuals, but these conclusions should be enough to indicate why scientists are concerned about what future generations will face from business- as-usual practices. We urge our policymakers and the public to move forward immediately to address the causes of climate change, including the unrestrained burning of fossil fuels.
We also call for an end to McCarthy- like threats of criminal prosecution against our colleagues based on innuendo and guilt by association, the harassment of scientists by politicians seeking distractions to avoid taking action, and the outright lies being spread about them. Society has two choices: we can ignore the science and hide our heads in the sand and hope we are lucky, or we can act in the public interest to reduce the threat of global climate change quickly and substantively. The good news is that smart and effective actions are possible. But delay must not be an option.
The signatories are all members of the US National Academy of Sciences but are not speaking on its behalf or on behalf of their institutions.