Medical conferences aim to improve health outcomes worldwide yet contribute substantially to global warming and climate breakdown. This is a paradox which cannot continue. Climate change is the “biggest global health threat of the 21st century”1Costello A Abbas M Allen A et al.Managing the health effects of climate change: Lancet and University College London Institute for Global Health Commission.Lancet. 2009; 373: 1693-1733Summary Full Text Full Text PDF PubMed Scopus (1620) Google Scholar and is causing an increase in heatwaves, wildfires, floods, droughts and crop failures, vector-borne diseases, mass migration, and is associated with an increase in air pollution. The evidence is unequivocal and the vast public health effects of the climate crisis1Costello A Abbas M Allen A et al.Managing the health effects of climate change: Lancet and University College London Institute for Global Health Commission.Lancet. 2009; 373: 1693-1733Summary Full Text Full Text PDF PubMed Scopus (1620) Google Scholar mandate that the medical community reconsider its role in contributing to this global catastrophe. With thousands of carbon-intensive flights, hotel stays, single-use merchandise, and food and plastic waste, the environmental profile of medical conferences is disastrous. Surprisingly, this profile has hardly changed despite the alarming evidence of growing environmental threats to health,2Watts N Amann M Arnell N et al.The 2018 report of the Lancet Countdown on health and climate change: shaping the health of nations for centuries to come.Lancet. 2018; 392: 2479-2514Summary Full Text Full Text PDF PubMed Scopus (439) Google Scholar and multiple calls to action for and from health professionals to tackle this impending health crisis. Unprecedented, ambitious action, and innovative thinking are urgently needed: carbon emissions must peak by 2020 and reach net zero globally by 2050 in order to protect human health.3Intergovernmental Panel on Climate ChangeGlobal warming of 1·5°C. World Meteorological Organization, Geneva2018Google Scholar Every action matters. To challenge the status quo, we propose a new model for international conferences. In August, 2018, we organised the General Assembly of the International Federation of Medical Students’ Associations (IFMSA), the largest annual gathering of medical students worldwide. For 7 days, we hosted 900 delegates from over 100 countries in Montréal, Canada, in a manner that was aligned with our environmental concerns. The IFMSA August Meeting 2018 was a pioneer in carbon-neutral international medical conferences. We believe that sustainable events should become the norm around the world. The first consideration when organising any event should be to establish whether an in-person meeting is needed at all, and how much of the event could be organised virtually: advances in technology make virtual participation more straightforward every year. In this Comment, we acknowledge this challenge. Nevertheless, we intend to outline that an international event can be organised in a responsible and sustainable manner. Between 2–5 tonnes of CO2 are emitted by every attendee flying intercontinentally to attend a conference.4AtmosfairThe Annual Climate Budget.https://www.atmosfair.de/en/green_travel/annual_climate_budget/Date: 2019Date accessed: January 15, 2020Google Scholar These emissions are above the annual yearly limit of 2·3 tonnes per person necessary to curb climate change.4AtmosfairThe Annual Climate Budget.https://www.atmosfair.de/en/green_travel/annual_climate_budget/Date: 2019Date accessed: January 15, 2020Google Scholar Hotels and conference venues are substantial emitters because of the intensive energy use of their buildings and operations.5Lenzen M Sun Y-Y Faturay F Ting Y-P Geschke A Malik A The carbon footprint of global tourism.Nat Clim Chang. 2018; 8: 522-528Crossref Scopus (596) Google Scholar Food service usually has generous portions of carbon-intensive foods such as meat and cheese, and often as much as 50% of catered food ends up in landfill.6Troitino C The tragedy of the buffet commons: reducing food waste at hotels.https://www.forbes.com/sites/christinatroitino/2017/09/14/the-tragedy-of-the-buffet-commons-reducing-food-waste-at-hotels/#196896d17dcdDate: 2017Date accessed: January 8, 2020Google Scholar Plastic bottles, single-use coffee cups, and event merchandise with short lifespans are widely available despite their substantial contributions to pollution. This scenario cannot continue. For the IFMSA August Meeting 2018, we estimated that the total footprint would be 1900 tonnes of CO2, the equivalent of 403 passenger vehicles driven for 1 year. An overview of carbon emissions from the August Meeting 2018 is shown in the appendix (p 1). Events ten times larger than this meeting are held by professional associations worldwide, emitting hundreds of thousands of tonnes of carbon-equivalent emissions every year.7Roberts I Godlee F Reducing the carbon footprint of medical conferences.BMJ. 2007; 334: 324-325Crossref PubMed Scopus (45) Google Scholar The detrimental effect of health-care conferences on the environment cannot be understated. Aside from emissions and waste, the detrimental effect of those conferences reflects a mentality disregarding climate breakdown and its consequences on health. We argue that medical events should set a standard of care for the environment—ie, a set of measures to ensure sustainable and carbon-neutral events. Sustainable medical conferences should lead by example and empower health-care professionals to do their duty in protecting the health of their patients and the planet at home, in the workplace, and within society. It is unreasonable to perpetuate an outdated conference format that goes against the principle that we, as health-care professionals, all vowed to follow: to do no harm. In our experience, achieving a carbon-neutral and sustainable conference was surprisingly simple. Success relies on reducing avoidable greenhouse gas emissions and waste in the first place, and compensating for unavoidable emissions through carbon offsetting as a last resort. Based on our experience and on existing guides for sustainable events,8United Nations Environment ProgrammeSustainable events guide: give your large event a small footprint. United Nations Environment Programme, 2012Google Scholar we encourage event organisers to implement the following key measures. (1) Consider whether the event needs to happen in person or could be organised virtually. (2) Create a position within the organising team, whose role is to focus on sustainability, as well as to research and implement environmentally-friendly options. No prior expertise is required, only systematic thinking and an evidence-based approach. (3) Formulate realistic, yet ambitious environmental objectives for the event early in the planning stages. Key interventions for a sustainable event should cover at least the seven categories listed in the panel. Offsetting flights is the single most effective intervention, as we estimate 85% of carbon emissions from our event were due to attendees’ flights.10Zotova O IFMSA August Meeting 2018 Sustainability Report.https://drive.google.com/file/d/1c5ibo8bZ9IqtIHaYTwyTaEL8FswPhtAp/viewDate: 2018Date accessed: January 8, 2020Google Scholar However, the total ecological footprint of conferences encompasses more than carbon emissions alone. (4) Monitor and report sustainability efforts, to celebrate successes and allow others to build on ideas and improve future attempts.PanelKey interventions checklist for a sustainable and carbon-neutral event.Raising awareness•Inform attendees of the eco-friendly measures implemented at the event and the reasons for these.•Advertise actions for attendees to reduce their ecological footprint.Carbon neutrality•Reduce greenhouse gas emissions at the source, by avoiding unnecessary emissions from transportation, venue and accommodation, catering, materials, and waste. Life-cycle emissions must be considered.•Maximise virtual participation and video conferencing.•Purchase carbon credits to offset emissions from flights and other event components, estimated by an emissions calculator. Budget offsetting costs in advance, and include an offsetting fee into registration as an opt-out if needed.•Choose the project to purchase carbon offsets with care.9Carlson D Lingl P Wong R Purchasing carbon offsets: a guide for Canadian consumers, businesses, and organizations. David Suzuki Foundation and Pembina Institute, 2009Google Scholar The project must be certified under an international standard such as the Clean Development Mechanism or Gold Standard and fit quality criteria to ensure real impact.Transportation•Prioritise low emitting and public transportation such as electric buses.•Ensure that venues are accessible by public transport.Venue and accommodation•Prioritise Leadership in Energy and Environmental Design certified venues.•Prioritise hotels implementing the Eco-Management and Audit Scheme or performing well in the Hotel Carbon Measurement Initiative.Catering•Maximally reduce availability of meat and dairy products, while providing a comprehensive range of vegetarian meals.•Reduce plate size to diminish food waste.•Donate all surplus food to local food redistribution organisations.Materials•Prohibit disposable bottles, cans, cups, plates, and cutlery. Ask attendees to bring their own cup, and provide washable plates and cutlery on site.•Limit merchandise to none, or one souvenir item per attendee.•Reuse materials from previous conferences or local education institutions.•Request minimal packaging from suppliers.Waste management•Provide waste sorting bins (including recycling and compost) with clear sorting instructions, and volunteers to assist in sorting at highly attended events.•Ask venue staff to record the amount of waste generated.For a more detailed framework and tips, refer to the UN Sustainable Events Guide.8United Nations Environment ProgrammeSustainable events guide: give your large event a small footprint. United Nations Environment Programme, 2012Google Scholar Raising awareness •Inform attendees of the eco-friendly measures implemented at the event and the reasons for these.•Advertise actions for attendees to reduce their ecological footprint. Carbon neutrality •Reduce greenhouse gas emissions at the source, by avoiding unnecessary emissions from transportation, venue and accommodation, catering, materials, and waste. Life-cycle emissions must be considered.•Maximise virtual participation and video conferencing.•Purchase carbon credits to offset emissions from flights and other event components, estimated by an emissions calculator. Budget offsetting costs in advance, and include an offsetting fee into registration as an opt-out if needed.•Choose the project to purchase carbon offsets with care.9Carlson D Lingl P Wong R Purchasing carbon offsets: a guide for Canadian consumers, businesses, and organizations. David Suzuki Foundation and Pembina Institute, 2009Google Scholar The project must be certified under an international standard such as the Clean Development Mechanism or Gold Standard and fit quality criteria to ensure real impact. Transportation •Prioritise low emitting and public transportation such as electric buses.•Ensure that venues are accessible by public transport. Venue and accommodation •Prioritise Leadership in Energy and Environmental Design certified venues.•Prioritise hotels implementing the Eco-Management and Audit Scheme or performing well in the Hotel Carbon Measurement Initiative. Catering •Maximally reduce availability of meat and dairy products, while providing a comprehensive range of vegetarian meals.•Reduce plate size to diminish food waste.•Donate all surplus food to local food redistribution organisations. Materials •Prohibit disposable bottles, cans, cups, plates, and cutlery. Ask attendees to bring their own cup, and provide washable plates and cutlery on site.•Limit merchandise to none, or one souvenir item per attendee.•Reuse materials from previous conferences or local education institutions.•Request minimal packaging from suppliers. Waste management •Provide waste sorting bins (including recycling and compost) with clear sorting instructions, and volunteers to assist in sorting at highly attended events.•Ask venue staff to record the amount of waste generated. For a more detailed framework and tips, refer to the UN Sustainable Events Guide.8United Nations Environment ProgrammeSustainable events guide: give your large event a small footprint. United Nations Environment Programme, 2012Google Scholar Sustainability needs to be at the core of all conference planning. Instead of depending on individual choices, environmentally friendly options should be the default option in all areas of the event. To encourage uptake and raise awareness, participants should be educated on the rationale behind these decisions before and during the event. For instance, attendees are unlikely to have inherent motivation to offset carbon emissions from their flights, so include carbon credits as an opt-out fee on the registration platform, and coordinate the purchase of carbon credits to offset the event's total emissions. Meat is often perceived as a commodity; therefore, serve several exclusively vegetarian meals to everyone. Prevent excessive food waste by reducing plate size; a proven strategy to reduce the amount of individuals’ leftovers. Knowing that attendees are accustomed to disposable containers, ask them in advance to bring their own cup, provide reusable cups for everyone, and aim to bulk buy in largest available containers to reduce packaging waste. Gifting new merchandise such as cups should be avoided though, and reusing items made a priority: new production is so resource-intensive that it takes several years for a reusable product to have lower emissions than it's equivalent single-use item. Altogether, comprehensive planning can be aided by detailed frameworks such as the UN Sustainable Events Guide.8United Nations Environment ProgrammeSustainable events guide: give your large event a small footprint. United Nations Environment Programme, 2012Google Scholar Local and international certification standards for sustainable events can provide formal recognition to conference hosts, thus contributing to stronger public image and enhanced funding opportunities. Additionally, institutions such as the Eco-Management and Audit Scheme can provide guidance and auditing of organisers’ efforts. The environmentally responsible and carbon-neutral IFMSA August Meeting 2018, successfully organised by students, sets a new standard for medical conferences worldwide. Every event within the health-care community is an opportunity to go a step further and push environmental sustainability to the top of the medical agenda. By challenging the status quo and pushing boundaries, we can cultivate a responsible attitude towards the planet, help tackle the climate emergency, and inspire professionals of all specialties to act to safeguard health on a planet in crisis. With only 11 years left to prevent catastrophic climate breakdown with significant threats to health,3Intergovernmental Panel on Climate ChangeGlobal warming of 1·5°C. World Meteorological Organization, Geneva2018Google Scholar social accountability is needed more than ever before. In an era when even the Olympics are going green, what are we, in healthcare, waiting for? We declare no competing interests. A list of further reading suggestions on the topic is available in the appendix (p 2). Download .pdf (.11 MB) Help with pdf files Supplementary appendix