Intended for healthcare professionals


A thought experiment: what should be our priorities when we finally “declare war” on climate change and the destruction of nature

BMJ 2024; 386 doi: (Published 05 July 2024) Cite this as: BMJ 2024;386:q1502
  1. Richard Smith, chair
  1. UK Health Alliance on Climate Change

The Romans had a formal system of declaring war, the ritual of rerum repetitio. A fetial, a special priest, wearing a woollen hairband would make demands of the enemy in its lands. If the enemy had not responded in 33 days then the Roman Senate would declare war, and the fetial would return to the enemy’s land and throw a javelin.

Many environmentalists have demanded governments and the United Nations to “declare war” on climate change, and David Attenborough said on the BBC in 2019: “If we have not taken dramatic action within the next decade we could face irreversible damage to the natural world and the collapse of our societies.”1 We have been making demands in our woollen headbands for decades, but now is the time to throw the javelin. A declaration of war gives governments remarkable powers like requiring young men to fight and die, rationing food and petrol, requisitioning land, vehicles, and much more, and imprisoning those who don’t black out their houses. These are the sorts of powers that are needed, but how would we use them?

Ironically the enemy we are fighting is not the Martians envisaged by H G Wells in The War of the Worlds (who invaded earth because they had severely depleted the resources on Mars) but ourselves—and there is, I suggest, no worse enemy. We would probably come together as humans to fight Martians, but can we come together to fight ourselves? In short, we must in order to survive, but the chance of every nation coming together seems small—look at the repeated failure of COPs (the annual UN meetings on climate change). Let me therefore restrict myself to imagining the UK declaring war on climate change. We did something not dissimilar very recently when we tried to come together to counter the pandemic, a much less serious threat than climate change. People mostly accepted repeated lockdowns, emptying our cities. Britain’s response didn’t go well, and a public inquiry is investigating how we could have done better.

Boring as it may be, the place to start with the war is to decide how it’s going to be run, its governance. Many deeply unpopular decisions will have to be taken, and the more trust people have in their leaders the more successful the war will be.

Get the governance right

Ngaire Woods, founding dean of the Blavatnik School of Government and professor of Global Economic Governance at the University of Oxford, looked at which factors had led countries to do well in countering the pandemic.2 She identified three factors, and the most important was effective collaboration between central and local governments. There need to be bodies that coordinate the collaboration, continuous dialogue, and transfer of resources. Also important is collaborative leadership that extends beyond politicians to health workers, epidemiologists, police, everybody with something to contribute. The third factor is negative: avoid warring factions. Luckily, there is probably much more agreement among climate scientists about how to respond than there was initially among health scientists on how to respond to the pandemic.

The advantage of declaring war is that the aim of winning the war—in this case reducing greenhouse gas emissions and restoring nature—takes precedence over everything else. Fortunately, achieving those aims will be good for the health of the people.

Slash the use of fossil fuels

Cutting fossil fuels will be the second war aim after establishing trusted governance as they account for three quarters of greenhouse gas emissions and 90% of carbon dioxide emissions.

All flying and private and business driving would be stopped apart from those trips deemed “essential” and which could not be done by walking, bicycle, train, or bus. Defining “essential” would be one of the first tests of governance. I suggest that almost no flying would be deemed essential: people could meet virtually, and no supplies would be flown in. Some driving would be necessary, and electric vehicles would be used whenever possible, which would be most of the time. Supplies, particularly of food, would need to be transported, but food supply would be dramatically changed (see below), limiting the amount of transport necessary. Ambulances, preferably electric, would be allowed, but I suggest that the number of journeys could be cut drastically because many ambulance journeys—for example, at the end of life—are not necessary. Hospital services would initially be restricted to emergencies only with active triage by experienced doctors to avoid all but real emergencies; other cases would be diverted to local primary care services. Schools would continue.

Most people, including most health professionals, would stop going to work while the economy was rethought (see below).

Dramatically increase renewable energy

While the consumption of fossil fuels was cut, a huge drive to increase renewable energy would begin. Windmills would be placed both offshore and in the best places on land. Little if any attention would be paid to those who objected. Both tidal energy and solar farms would be increased, and solar panels would be placed on as many buildings as possible.

Reduce energy the consumption of homes

Heating homes accounts for about a seventh of greenhouse gas emissions in Britain. In direct contrast to the pandemic, people would be encouraged to move in with relatives and friends. Tourism would stop, and most hotels would be empty, but some hotels would be kept open and people, particularly those living alone, would be encouraged to move into them. People would be required to turn down the heating in their houses to 17C and to turn it off at night. There would be a 9pm curfew, and people would be encouraged to sleep during the hours of darkness.

There would be a huge drive to insulate homes, install heat pumps, and add solar panels and even windmills to roofs and gardens.

Transform agriculture and the nation’s diet to be largely-plant based

The food system accounts for around a third of greenhouse gas emissions, and about two thirds of the emissions from food production are attributable to meat production. Food waste is responsible for 8% of all emissions or about a quarter of those from the food system.

Yet about four in 10 of the world’s population is obese or overweight, while one in 10 goes to bed hungry. Something is badly wrong with the world’s food system.

Agriculture in Britain would be changed as quickly as possible with a dramatic reduction (but not elimination) of production of meat and dairy and an increase in the production of fruit and vegetables. Imports of food, particularly of tropical foods with high carbon footprints, would be reduced as far and fast as possible.

Meat and dairy would be rationed, and mass education and media campaigns would encourage people to switch to diets that are mainly plant-based and reduce food waste. Just as food rationing during the Second World War was associated with improvements in health, the same would be seen as a result of rationing and education.

All institutions required to make progressing to net-zero a priority

Cuts in fossil fuels and changes in agriculture, which could be mandated centrally, would cut Britain’s emissions, but the government would require all institutions, both public and private, to make cutting greenhouse gas emissions its top priority. Carbon footprints would be measured, audited, and published annually.

Collect and recycle waste and buy less

British homes, businesses, and organisations are full of objects no longer used: electronic equipment, clothes, books, furniture, bottles, toys, and much more. The government would gather this waste together and either redistribute or recycle it. Every home and organisation would be required to develop a plan for minimising consumption and waste. It is excess consumption that is killing the planet, and there would be mass education to encourage people to buy less and reuse and repair much more. Schemes would be introduced to encourage the sharing of implements—for example, electric drills—that are rarely used but found in many homes.

Rethink and transform the economy

We have an unsustainable economic system, and if we don’t transform it, we will achieve nothing except a brief delay by declaring war on climate change. But such a declaration could give time for designing and transforming our economy.

In simple terms economies based on infinite growth, the current economic wisdom and political commitment, are not compatible with the finite resources of the planet. As Katie Raworth describes it in Doughnut Economics, we currently have a caterpillar of “take-make-use-lose” eating the planet’s resources and producing unsustainable amounts of waste.

Increasing numbers of economists have recognised the inadequacy and unsustainability of present economic thinking and the economic system, but at the same time nobody has a readymade new model. But Raworth in her book outlines a route to take, issues challenges to 21st economists, and describes cases where people have made innovation along the line of what she’s proposing.

She foresees seven steps. Firstly, the goal of the economy should not be a bigger gross domestic product (GDP) but an economy that gives everybody in the world basics like an income, food, shelter, and education, but does not destroy the planet.

Raworth recognises the power of pictures, and her book is named after the ring doughnut she drew many years ago: the border of the inner ring ensures that everybody has access to the basics, and the border of the outer ring stops damage to the plant. The aim is to have the economy and everybody in the doughnut, but at the moment the inner ring is breached because so many in the world do not have access to the basics—and the outer ring is breached because we have moved beyond planetary limits.

Secondly, we should end the current obsession with the market and recognise the importance of other parts of the economy, including the state, the commons, and the household. The market has its role, but so do these other parts.

Thirdly, economic theory and economic systems should abandon the illusion of rational economic man and nurture the richness of all that humans want to achieve and our interdependence.

Fourthly, we need to recognise the complexity of systems and how interventions can have unintended consequences. Linear thinking has been useful, but also misled us, and more and more people are recognising the importance of systems thinking for many challenges—not least climate change, global poverty, and obesity.

Fifthly, we should “design to distribute.” We live in a highly unequal world, where the richest 1% own almost half of the world’s wealth; and in Britain the richest 1% own as much wealth as 70% of Britons. Indeed, probably one of the actions we should take as part of the declaration of war is an immediate wealth tax on the richest—this will provide funds to support many through what will be a hard time.3

There are famous curves in economics called Kuznet’s curves that suggest that as countries grow richer they first experience increased inequality and pollution, but then as they grow richer become more equal and less polluting. Raworth shows how the curves mislead and argues that instead of redistributing income or wealth once its accumulated distribution should be built into the design of the economy.

Sixthly, recognising that “growth will not clean it up again,” we need an economy that will give back to nature just as a tree in the forest grows absorbing water, nutrients, and carbon dioxide, but gives back shade, shelter to many creatures, oxygen, and eventually its whole body as it dies and decays. This is a vision way beyond a net-zero economy, and it’s a great challenge to think what a “regenerative health system” would look like.

Lastly, Raworth asks 21st century economists to abandon the idea that economic growth is essential and think beyond it.

Without a redesigned economic system we will have little chance of sustaining the planet and its people, but while economists are redesigning the economy health professionals need to be designing the health system. Our future may not depend crucially on redesigning the health system, but we should recognise that we have a caterpillar health system just as we have a caterpillar economy.

Conclusion: the value of a declaration of war

A declaration of war on climate change and the destruction of nature might initially be unpopular, but it may well become possible as increasing numbers of people recognise the seriousness of our predicament and how radical is inevitable. The beauty of a declaration is that it would give the whole country a clear priority and would free people from working at enterprises that are often damaging the planet and give them time to think up a better way to live. I’ve played with some ideas in this thought experiment, but the declaration would unleash the human imagination and creativity that got us into this mess but also has the capacity to get us out of it to a better place.


  • Competing interests: RS is chair of the UK Health Alliance on Climate Change, but the views expressed in this piece are his personal thoughts.