London School of Hygiene & Tropical Medicine

Climate change is ‘unequivocal’ and ‘unprecedented’. Take home messages from a recent UN report dubbed ‘a code red for humanity’.

What is also clear is that climate change is precipitating a global health emergency. More than 30% of heat-related deaths over recent decades can be attributed to climate change. Mosquito borne infections malaria and dengue are predicted to affect billions more people as global warming continues.

The UK’s temperate climate does not make us immune from the worst of climate change, from recent ‘once in a generation’ devastating floods and heatwaves, to a healthy diet coming under threat due to a large chunk of our fruit and vegetables being imported from climate-vulnerable countries.

While it’s heartening to hear the Climate Change Committee say the UK strategy to reach net zero emissions by 2050 is ‘achievable and affordable’, the impact of climate change on human health continues to be under emphasised, highlighted by its limited presence at COP26. Failing to reach net zero will have devastating consequences for human health.

What more can be done to ensure this crucial milestone is achieved? If the UK and others are going to achieve ‘net zero’ in time, the biggest and most successful behaviour change campaign ever must happen, and fast.

In theory, the co-benefits of mitigation should be the perfect platform to launch this ambitious but crucial goal. A greener future means more jobs in new sustainable industries which will boost national productivity.  Well planned and delivered greenhouse gas mitigation policies will boost human health, now and in the future.

Millions of lives can be saved every year annually by switching to renewable energy and reducing air pollution and heating of the planet. Getting on a bike instead of behind the wheel of a fossil-fuel car will curb emissions and boost health. Eating and drinking more environmentally sustainable foods will extend life expectancy. These are not new messages, but they must be heard and acted upon.

Of course it’s not that simple.

As Marteau and colleagues explained in a recent BMJ article, the environments that drive human behaviour are key - ‘changes to diet and land travel can be achieved through policies to increase the availability and affordability of healthier and more sustainable options’.

Behaviour change on such a massive scale isn’t easy but history shows effective public health campaigns can help, from seat belts to vaccinations, and of course smoking.

However, we are only just beginning to see full the health impact of climate change, with the worst yet to come. Many of the adverse health effects are long term, building gradually over generations. But they are relentless, and without action now, human health will suffer on a massive scale. This lack of immediacy, especially alongside the current devastating pandemic, may explain the relatively low-priority given to health in the debate around climate change.

So we need to change the narrative.

Its influence on health will only grow in the future leading to changes in the key determinants of health – such as diet, the air we breathe, where we live and levels of circulating infection – as well as changes to patterns of diseases and the necessary responses by health services.

This is why our generation must look hard in the mirror and face the fact that it’s the generations to come whose health is made far more uncertain through climate change – change that we and our ancestors have fuelled and continue to do so.

Talking about climate change in the same breath as smoking might be a catalyst for change. By stopping filling our bodies with dangerous chemicals our health dramatically improved. If we stop filling the atmosphere with carbon dioxide and methane, our grandchildren’s health will benefit too.

Further global change requires innovation and a rethink of narrow lens strategies.

Health in richer nations was radically improved through improved living standards, largely driven by the industrial revolution that in turn was largely driven by use of fossil fuels. We cannot deny the huge positive benefits of development to lower income populations – all people need clean water, food security, adequate health care, universal education, and access to good contraception – examples of wider determinants that we know drive health improvements.

Ensuring such development can progress sustainably in resource constrained settings needs progress on two key fronts. Firstly, we need a strong evidence base rooted in the local context to guide policy and practice. Secondly, we need to build expertise through education and training.

COP26 has arrived. It’s ironic that Britain is hosting this crucial international climate change conference when in terms of national policy we are largely thinking locally not globally. The UK government’s decision to massively reduce its overseas aid budget will have a devastating impact on many people around the world who were already facing enormous difficulties, and who will bear the main brunt of climate change.

The reasons for this decision are hard to fathom. What is clear is that we need a new era of public health with planetary health at its heart.

Central elements of our response to climate change must be generating the robust evidence needed to underpin action, and training and inspiring the next generation to improve human health.