I’m preparing for a BBC Radio 4 debate on whether we can look forward to a healthier future, and I’m cast as the pessimist who must argue that the future will be less healthy. Here is my case.

The whole debate could centre on how we define health. WHO may define it unrealistically and ambitiously as “complete physical, mental, and social well-being,” but most doctors define it day to day as the absence of disease. That’s also how ordinary people think about it, so that’s the definition I’ll use.

The debate takes place at the London School of Economics in the context of an NHS that is under great pressure, but when we are discussing health we must take a global perspective.

Destruction of the planet

The biggest threat to the future of health is that we have almost destroyed our planet. The Stockholm Resilience Centre defines nine planetary boundaries, which characterise the circumstances in which we can enjoy a flourishing civilisation. We have crossed five of these boundaries: extinction rates, climate change, land use change, phosphorous and nitrogen cycles, and ocean acidification; and we are at the limits of three others: freshwater use, pollution by novel agents, and atmospheric aerosol loading.

So we are at the limits of what the earth can take, yet the global population is rising and people are expecting a higher standard of living. The global population is expected to grow from 7 billion now to over 9 billion by the middle of the century. If everybody lived as many poor people in Africa and South Asia live then we could get by with one planet, but if everybody lived as people live in North America we would need five planets—or as people live in Western Europe three planets. People in North America and Western Europe are reducing their energy consumption and ecological footprint—but not by much and they are a small proportion of the global population. Most people are increasing their consumption and ecological footprint and there are more people—so we don’t have enough earths.

The effects on health will be partly an increase in tropical diseases and impact from extreme weather, but most of the damage to health will come from drought, famine, starvation, mass migration, and war. People are currently crossing the Mediterranean for a better life, but by the end of this century it may be impossible to live anywhere around the Mediterranean.

Growing inequality

And, of course, it’s the poor who suffer most from environmental degradation even though they are not the people who caused the problem. The richest 90 people own as much as the poorest 2 billion, and in most countries the Gini coefficient, which measures the degree of inequality, is getting worse. The worst maternal mortality rate is in Chad where 980 women die per 100 000 live births, while in Singapore the number is 2. In Sierra Leone, 183 children of every 1000 live births die before they reach the age of 5, while in Luxembourg the number is 2. Every night 1 billion people go to bed hungry, and 800 000 have no ready access to sanitation or fresh water.

Yet North America has 2% of the health burden, but 25% of the healthcare workers, while Africa has 25% of the burden and 2% of the workforce.

Emerging diseases

The next major threat is emerging diseases, which are the result of creating an unhealthy planet where we can feed ourselves only through industrial and unhealthy agricultural processes. New diseases are coming along faster: since I graduated from medical school we’ve had AIDS, SARS, Avian flu, Ebola, MERS, Zika, and many more that most people have never heard of. So far we have been lucky in that relatively few people have been affected, but Professor Tom Koch from the University of British Columbia, one of the world’s leading experts on emerging diseases, says that within eight years we will have a major pandemic of a new and untreatable infection that will affect 60% of the population and have a mortality of 30-35%. He used to say with ten years, but he recently shortened it to eight years.

We are not well prepared for the epidemic that will inevitably come, eventually, if not in eight years.

Antimicrobial resistance

Humans have created the conditions which lead to emergent diseases, and unfortunately we are also frittering away the effectiveness of one of medicine’s treasures—antibiotics. Because of overuse of antibiotics in medicine and agriculture, microbes are rapidly developing resistance to antibiotics. The first antibiotics appeared only in the 1940s and within a century they are likely to use their usefulness. We are racing against evolution, and when bacteria can reproduce every 20 minutes with each episode of reproduction providing a chance to develop resistance, it’s a race we are almost bound to lose. Technical innovation cannot keep up.

The result of antibiotics becoming useless is that much of modern medicine—particularly complex surgery, intensive care, and chemotherapy—will become impossible.

The pandemic of NCD

Although one billion people in the world are hungry, one billion are obese, and obesity and its companion diabetes are increasing rapidly. Around 70% of adults in high income countries are obese or overweight, and the number of people with diabetes is expected to grow from 300 million now to 440 million by 2030. The spread of smoking, poor diet, physical inactivity, and the harmful use of alcohol is causing a pandemic of non-communicable disease (NCD)—that is heart disease, stroke, diabetes, chronic obstructive pulmonary disease, and cancer. NCD causes 80% of global deaths now, which is around 40 million a year, and WHO predicts that the number will increase to 55 million by 2030. Our response to this global pandemic has been very slow.

Health/sickness care promotes poor health

Now I turn to healthcare. Healthcare accounts for about 10% of health—the environment, genetics, and lifestyle account for the other 90%. And, although we call it healthcare everybody knows that it’s really sickness care—and healthcare actually increases ill health in several ways. There are cases—for example, treating meningitis—where a person is seriously sick and may then return to full health; but very little of healthcare leads to cures. Most health problems these days are long term conditions—like heart disease, diabetes, dementia, Parkinson’s disease, asthma, arthritis, many cancers, and chronic respiratory disease from which people are not cured. I’ll now explain how healthcare/sickness care increases ill health.

Firstly, although life expectancy is increasing unhealthy, life expectancy is increasing faster. Among Scottish women, for example, life expectancy is about 80, but healthy life expectancy is about 60—meaning that a Scottish woman spends about 20 years in ill health. People are kept alive but are unhealthy. They might, for example, be demented, blind, deaf, arthritic, depressed, or being treated with toxic chemotherapy for cancer.

At the other end of life, ever smaller babies are being kept alive—but most of the smallest with severe and expensive disabilities.

Secondly, the costs of health/sickness care keep increasing faster than inflation. Part of the cause is ageing of the population, but most of the cause is simply that more can be done—ever more expensive drugs to treat cancer and other conditions, expensive scanners, innovations in intensive care, heroic surgery, genetic testing, and much else. Unfortunately most innovation in health/sickness care increases rather than decreases costs as is the case with phones, computers, cars, and much technology. This may be because most health innovation needs more skilled and expensive people to work them, and about three quarters of the costs of a health system is people. Unfortunately, most of these expensive innovations do not add much value—as is the case, for example, with cancer drugs costing £60 000 a year but giving only weeks of extra life, much of it miserable because of severe side effects.

The result of rising healthcare costs is that they “crowd out” spending on education, housing, the environment, and the like which actually can increase health rather than sickness.

Medical error: the third leading cause of death

Thirdly, healthcare, particularly hospital care, is dangerous. We’ve known for 30 years, although we’ve been slow to do anything about it, that about 10% of people admitted to hospital are damaged by the care and about 1% are killed. Medical error is the third cause of death in the United States behind heart disease and cancer—and it’s probably the same in the UK, although we’ve been less open about the problem.

Rising levels of poor mental health and antidepressant prescribing

I want now to consider mental health. Many studies show a steady rise in the prevalence of mental health problems from the 1930s. About one in four people in Britain has a mental health problem in any one year. Prescriptions for antidepressants have doubled in the past decade—from about 15 million in 2006 to over 31 million in 2016. That’s more than one prescription for every two people.

Amartya Sen, the Nobel prize winner, has observed an inverse relationship between mortality and self-reported levels of health. More people in Bihar, India’s poorest state with low life expectancy, report being healthy than in Kerala, India’s state with one of the highest life expectancy; and people in Western Europe and North America, where life expectancy is still higher, report even lower levels of health. So reduced mortality does not mean better health.

Loneliness, the “disease” of our age

Finally, I want to consider loneliness, which I think is the “disease” of our age even though medicine doesn’t recognise it as a disease and can do nothing about it. According to the Canadian psychologist Ami Rokach who has long studied it, “acute loneliness is a terrorising pain, an agonising and frightening experience that leaves a person vulnerable, shaken, and often wounded.”  Yet in Britain 17% of older people are in contact with family, friends, and neighbours less than once a week and 11% are in contact less than once a month. Over half (51%) of all people aged 75 and over live alone. Two fifths of older people (about 3.9 million) say the television is their main company. Levels of reported loneliness are increasing.

Healthcare has helped keep people alive, but left many to a life of loneliness, a condition that is far from healthy.

Conclusion

Our future is undoubtedly a less healthy one, and environmental destruction could mean that we won’t even have a future. We know that humans, like all species will eventually become extinct, and some highly respected scientists think that could happen in the next 100 years. I fear for my grandchildren.

Richard Smith was the editor of The BMJ until 2004.

Competing interests: None declared.