Authors:

• Dr Mary Slingo, Consultant Anaesthetist, University Hospital Southampton
• Dr Li Fang, Consultant Anaesthetist, Salford Royal Hospital
• Dr Lucy Brooks, Specialist Registrar, Yorkshire and Humber School of Anaesthesia and Intensive Care
• Dr Helgi Jóhannsson, Consultant Anaesthetist, Imperial College Healthcare NHS Trust
• Dr Paul Southall, Consultant Anaesthetist, Worcestershire Acute Hospitals NHS Trust
• Environmental Advisors to the RCoA

Sustainable anaesthesia is going from strength to strength. Significant progress has been made in recent years through awareness, education, policy changes, and technological innovations. 

At the start of this year, it feels like a good time to reflect on what we’ve learned and think about what green anaesthesia looks like in 2026 and beyond.

Different greenhouse gases have different effects

A greenhouse gas is one, which traps energy from the sun in the Earth’s atmosphere, resulting in global warming. The Earth is not a simple ‘box’, and there are all sorts of thermal sinks (eg, the oceans) and latencies which mean that any efforts by a greenhouse gas to ‘force’ the climate in a new direction need to be of sufficient duration and magnitude.

There are lots of greenhouse gases, and they affect the climate in different ways. One key difference is whether a gas is long-lived in the atmosphere or short-lived. CO₂ has an extremely long (millennial) lifetime, which means that emissions have a cumulative impact. Any emission will keep raising temperatures, so to halt warming, all CO₂ emissions need to be ‘zeroed out’. Actions such as direct removal from the atmosphere and reforestation provide some limited opportunities for ‘net’ zero, but the primary objective must be for all CO₂ emissions to cease.

In contrast, short-lived gases such as the volatile anaesthetics have lifetimes of approximately a decade or even less. The warming from a one-off emission declines rapidly as the gas is broken down; a constant emission rate results in a relatively stable, not continuously increasing, amount of warming. A plateau is reached, and no further warming takes place unless emissions rise steeply.

The magnitude of warming from emissions of short-lived gases is determined, in part, by the chemical properties of the gas in question and the number of molecules released into the atmosphere. In the case of the volatiles, regardless of their potency per molecule as greenhouse gases, their lifetimes are too short, and their atmospheric concentrations are too small to have any meaningful impact on the climate.

Why then the concern about volatiles?

International climate policy requires a way of placing different gases on a common scale so that they can be traded and budgeted as ‘equivalent’ CO₂ emissions, and the most widespread metric used is the GWP100 (Global Warming Potential – a misnomer, since it does not accurately tell us the potential of an emission to cause global warming). The problem with this, which is well documented by climate scientists and the IPCC, is that it obscures vital differences in the response of the climate system to emissions of long-lived and short-lived gases. This has led to inappropriate emphases on mitigating short-lived gases when real CO₂ reductions should remain the priority. Recent work has demonstrated this clearly, and we recommend the ‘further reading’ to understand why an emission of a volatile cannot be ‘equivalent’ to a certain emission of CO₂.

What does this mean for desflurane?

The decrease in desflurane usage was enacted in good faith and based on anaesthetists’ understanding at the time of GWP, and it began before the work demonstrating that its ‘CO₂-equivalence’ was misleading. It has shown the strength and enthusiasm of the anaesthetic community for enabling green initiatives, and we celebrate such positivity. However, with greater engagement with climate science, we must accept that GWP has misled us. We fully support those anaesthetists using desflurane within the new parameters set out by NHSE, supported by NICE’s evidence review, which found no clinical advantage to using desflurane for routine cases. We are reassured that using desflurane within those parameters will result in minimal climate impact, and we are also encouraged that ceasing desflurane use outside of those parameters will not adversely affect patient care.

What does this mean for TIVA?

All of the comparisons of TIVA vs volatiles have been made using the GWP-based CO₂-equivalence method. The problem with this is that TIVA inevitably requires numerous additional plastic syringes and administration lines, which must be manufactured and incinerated, and the ecological impact of propofol remains under-researched. GWP-based comparisons of the real CO₂ from this plastic and the ‘CO₂-equivalence’ of the volatiles give misleading guidance for policy-makers. It is not possible to compare them accurately in this way, therefore TIVA should not be chosen solely for environmental reasons. As with everything we do in healthcare, TIVA usage comes with benefits and risks that need to be considered carefully. We strongly advise that the most appropriate anaesthetic technique is chosen based on what is best for the patient and the procedure, and that the environmental impact and CO₂ emissions are minimised regardless of choice. We also strongly support robust training for resident anaesthetists in both techniques to enable competent patient care and decision-making.

What about nitrous oxide?

Nitrous oxide is an important greenhouse gas due to its longevity and abundance. Recent work by the RCoA and the Association of Anaesthetists to decommission all piped nitrous oxide is an important and exciting development. We support those anaesthetists who still require it in their clinical practice, but strongly encourage low-flows and the use of point-of-care cylinders.

Green anaesthesia in 2026

Over the past few years, our understanding of climate change and the impact of different greenhouse gases has improved and expanded, and we’ve learned how difficult it is to infer climate impacts from trace gases using simplified metrics. It is irrefutable that carbon dioxide remains the single-most important anthropogenic greenhouse gas. All of our endeavours in sustainable anaesthesia must be focused on reducing real CO₂ emissions and ensuring that we do not inadvertently increase them. With better climate literacy and integration of sustainable healthcare at institutional levels, we can all make a difference.

Further reading

• Impact of desflurane
• Short-lived gases
• Nitrous project
• Climate science
• Nice summary