If we carry on as now we will need 2.3 planets to support the 9 billion people who will be alive in 2050, says the World Business Council for Sustainable Development. This is a relatively uncontroversial statement, and it probably hasn’t escaped your attention that we don’t have 2.3 planets. We have only one. So we have to change—or perhaps live in an intolerable world (if we don’t already) where those who have energy, water, and wealth fight off those who don’t.

What does this mean for the Britain’s health system, something broader than the NHS but in which the NHS is a huge chunk? This was the subject for a day’s discussion this week organised by the NHS Sustainable Development Unit. Its plan is to take the output from the discussion, refine it into a vision and a roadmap for the health system, and present it to the world on 1 February 2011 (put the date in your diary).

In 2007 the NHS had a carbon footprint of 21 million tonnes of carbon dioxide, about the same as the whole of Portugal. The footprint is comprised 60% by the activities of companies producing goods and services for the NHS, 17% the travel of patients, staff, and visitors, and 23% heating, lighting, ventilation, and cooling. The current forecast is for carbon consumption to increase, but the NHS is legally required to reduce consumption by 10% by 2015 and by 80% to 1990 levels by 2050.

Anybody can see that this requires huge change—transformation in fashionable jargon. How to do it?

The World Business Council for Sustainable Development provides an interesting model of how to go about the change, and it was described at the meeting. Some may think that business is part of the problem not the solution, but businesses are anxious both to survive and grow—and they see huge business opportunities. The “green race is on,” and Unilever, for example, has set a target to double turnover while reducing its environmental impact.

The business council conducted a global exercise among some 200 companies, many of them major polluters, and began by convincing themselves that business as usual (increasingly known as BAU, watch out for it) is not an option. They then set a vision of how the world will be in 2050. They assumed (a fair assumption) that there would be 9 billion people, most of the “new” people will be old and living in cities, many of them megacities, in the developing world. In the vision they are all living well, almost as well as most readers of the BMJ live now.

The plan looked at everything, and the next step was to identify key steps with materials, mobility, buildings, energy, forests, agriculture, the economy, human development, and values. Admitting themselves to be amateurs when it comes to values, the businesses decided that change in those values was probably more important than any other change. From the key steps came targets, very tough targets like all buildings (all, not just new buildings) being carbon neutral by 2050.

The benefits of this process were that it was global and “big picture.” It has created a vision, roadmap, and targets, and it leaves the detail of how to make it happen to the many businesses and players. To mix clichés “the devil may be in the detail,” but if you don’t have a “vision and a roadmap” you get “Brownian rather than forward motion.”

So the challenge is to create something similar for Britain’s health system and then leave health authorities, hospitals, commissioners, GPs, and many others to make it happen—with regulatory oversight. It’s hard for those of us embedded in the old paradigm to envision the new, but we made a modest attempt. We tried to see the health system in a Britain consuming 80% less carbon, with 10 million more people, a 30% smaller tax base, where every other summer would be as hot as that in 2003 when mortality went up 17%,  and where all people and all our back up resources (house, fridge, toilet, etc) are online all the time.

We envisioned a world in which people and patients would take much more responsibility for the health of themselves and their families. People, patients, families, and communities would be more important, and professionals less important. (Could this be the “big society”?)

Telehealth would increase dramatically, meaning a huge improvement in information for people, patients, and clinicians, decision aids, computer assisted history taking, information from sensors in smart houses, online, perhaps asynchronous, consultations, robotic surgery, and much else, some of it yet neither imagined or created. It’s been estimated that 40% of clinician patient consultations could be online today, but in this future world fewer problems may need consultation with professionals and a higher proportion might be conducted electronically—perhaps through virtual reality. Telehealth like green energy presents tremendous business opportunities.

Resources will shift from sickness to wellness, and social care will become as important as health care—because most of health care, as now in the developed world, will be concerned with elderly, frail people with multiple problems. Routine sequencing of genes will help shift health care from “diagnose and treat” to “predict and prevent.” Attitudes to death will change, and assisted suicide will become routine. The National Institute for Clinical Excellence will be concerned more with carbon effectiveness than cost effectiveness, and many interventions will be excluded because they consume too much carbon.

These are all preliminary thoughts, and the sustainable development unit has much work to do. But I had the privilege of asking the audience questions at the end of the meeting and when I asked whether the challenge of sustainability was an opportunity or a threat everybody thought it an opportunity. Was it because they were highly selected optimists or might they be right?

Competing interest: RS is chair of Patients Know Best, a start up that uses information technology to enhance patient clinician relationships—including promoting online consultation. He is not paid but has equity in the company.

Richard Smith is a former editor of the BMJ.