We support the call by Slingo and Slingo for anaesthetists to adopt a sustainability framework informed by climate science, which urgently stresses the need to reduce our climate impact [1]. As rightly emphasised, the global warming potential (GWP) metric has faced criticism for overestimating the climate impact of short-lived climate pollutants and potentially leading opportunistic policymakers to focus on mitigating short-lived climate pollutants rather than reducing carbon dioxide emissions, which have climate implications for millions of years [2]. However, this critique cannot be indiscriminately applied to volatile anaesthetics. In healthcare settings, reducing desflurane emissions will not lead to increased carbon dioxide emissions from other sources. We also contend that there are more appropriate metrics than radiative forcing. As Grant eloquently stated, comparing the emissions of a very small professional group to the total historical emissions of all greenhouse gases by humanity to dismiss their impact as insignificant conveniently absolves any accountability and calls for appropriate and scientific justification [3]. In their response, Slingo and Slingo failed to substantively explain why they consider radiative forcing the superior alternative. Moreover, contrary to their claims, the Intergovernmental Panel on Climate Change does confirm that all known factors are considered in the reported GWP values, ensuring its reliability as a metric to describe the actual effects.

While the short lifetime of volatile anaesthetics complicates their comparison with carbon dioxide, considering the time horizon may help understand their climate impact: a suitable measure to elucidate greenhouse impact is cumulative heat absorption over variable time horizons. With a radiative efficiency of 0.464 W.m^-2.ppb^-1 of desflurane being 35,000 times stronger than the radiative efficiency of carbon dioxide and an atmospheric lifetime of 14.1 years, the amount of heat absorbed by the planet in the first 20 years after emission of one 240 ml bottle of desflurane is 998 gigajoules [4]. This absorption is equivalent to that of 1790 kg of carbon dioxide over the same period.

Over 100 years, 240 ml desflurane irreversibly absorbs 1315 gigajoules, which equals the absorption by 510 kg of carbon dioxide over 100 years. The decision on the most appropriate time horizon for estimating carbon dioxide equivalences (CO₂e) of desflurane depends on perspectives regarding three key topics: the urgency of climate change; views on the validity of positive feedback mechanisms in climate change [5]; and the attribution of emissions resulting from the anaesthetists' choice.

We consider climate change an urgent issue for the near future, with imminent positive feedback mechanisms exacerbating its impact. Furthermore, we contend that the choice of volatile anaesthetic primarily serves anaesthetists' convenience offering, in most cases, no significant benefit to patients [6]. Based on these premises, we assert that a 20-year time horizon best reflects the actual consequences of desflurane use. Utilising desflurane in minimal flow for 2000 hours annually, consuming 175 bottles, results in 313,000 kg of CO₂e emissions.

The ethical justification for contributing to climate change by causing emissions equivalent to those of 44 average Europeans, solely from one single, arbitrary choice, rests with the anaesthetist's professional assessment. As with any clinical decision, anaesthetists must fully comprehend the true consequences of their choices, grounded in scientific facts. Furthermore, while Slingo and Slingo emphasised that saved emissions should not justify emitting 313,000 kg of carbon dioxide elsewhere, we contend that this argument is not pertinent.

我们支持 Slingo 和 Slingo 呼吁麻醉师采用以气候科学为基础的可持续发展框架，该框架迫切强调减少我们对气候影响的必要性 [ 1 ]。正如正确强调的那样，全球变暖潜能值 (GWP) 指标因高估了短期气候污染物对气候的影响而受到批评，并可能导致机会主义政策制定者专注于减轻短期气候污染物，而不是减少二氧化碳排放，这对气候产生了影响。数百万年的影响[ 2 ]。然而，这种批评不能不加区别地应用于挥发性麻醉剂。在医疗保健环境中，减少地氟醚排放不会导致其他来源的二氧化碳排放量增加。我们还认为，有比辐射强迫更合适的指标。正如格兰特雄辩地指出的那样，将一个非常小的专业团体的排放量与人类所有温室气体的历史排放总量进行比较，将其影响视为微不足道，可以轻松地免除任何责任，并要求适当和科学的理由[ 3 ]。在回应中，Slingo 和 Slingo 未能实质性解释为什么他们认为辐射强迫是更好的选择。此外，与他们的说法相反，政府间气候变化专门委员会确实确认在报告的全球升温潜能值中考虑了所有已知因素，确保其作为描述实际影响的指标的可靠性。

虽然挥发性麻醉剂的寿命较短，使其与二氧化碳的比较变得复杂，但考虑时间范围可能有助于了解其对气候的影响：阐明温室影响的合适措施是不同时间范围内的累积热量吸收。地氟醚的辐射效率为0.464 Wm ^-2 .ppb ^-1，比二氧化碳的辐射效率强35,000倍，其大气寿命为14.1年，相当于地氟烷排放后20年内地球吸收的热量。一瓶 240 毫升地氟烷的能量为 998 吉焦 [ 4 ]。这一吸收量相当于同期吸收1790公斤二氧化碳。

100 年来，240 毫升地氟烷不可逆地吸收 1315 吉焦耳热量，相当于 100 年来吸收 510 公斤二氧化碳。估算地氟烷二氧化碳当量 (CO ₂ e) 的最合适时间范围的决定取决于对三个关键主题的看法：气候变化的紧迫性；对气候变化正反馈机制有效性的看法[ 5 ]；以及麻醉师的选择造成的排放的归属。

我们认为气候变化是近期的一个紧迫问题，迫在眉睫的积极反馈机制加剧了其影响。此外，我们认为挥发性麻醉剂的选择主要是为了麻醉师的方便，在大多数情况下，对患者没有显着的好处[ 6 ]。基于这些前提，我们断言 20 年的时间范围最能反映地氟醚使用的实际后果。每年以最小流量使用地氟烷 2000 小时，消耗 175 瓶，会导致 313,000 公斤 CO ₂ e 排放。

仅出于一个任意的选择，造成相当于 44 个欧洲人平均排放量的排放量，从而导致气候变化，其道德理由取决于麻醉师的专业评估。与任何临床决策一样，麻醉师必须以科学事实为基础，充分理解其选择的真正后果。此外，虽然 Slingo 和 Slingo 强调节省的排放不应成为在其他地方排放 313,000 公斤二氧化碳的理由，但我们认为这一论点并不恰当。