22/05/2015 16:25 BST | Updated 23/06/2016 06:59 BST

Five Ways to Stop the Threat to Global Health From Climate Change

Five years ago, the first Lancet Commission called climate change "the biggest global health threat of the 21st century". The second report of the Commission, published on Saturday 23 May 2015, raises the stakes higher still. Current greenhouse-gas emissions-projections, and consequent climate change, pose an unacceptably high and potentially catastrophic risk to human health, the Commission reports.

A report for the IMF, published earlier in the week, allows such warnings to be translated into estimates for economic losses. If we count both the direct cost of subsidies to fossil fuels, and the cost of damage created in fossil-fuel use, the total impact is $5.3 trillion per year, 6.5% of global GDP, a sum exceeding the total annual health spending of all governments. Just over half involves money governments are forced to spend treating the victims of air pollution, plus income lost because of ill health and premature deaths. Ending the subsidies would also halve premature deaths from outdoor air pollution, saving some 1.6 million lives a year. The authors emphasise that all their estimates are conservative.

How does the Lancet Commission propose to approach this enormous collage of loss? Five main conclusions arise from their work. Let me consider each in turn.

First, we need to think of it in terms of opportunity. Tackling climate change could be the greatest global health opportunity of the 21st Century. Apart from the human misery escaped if we cut some of those lost trillions of dollars, imagine the net benefits if we invest the deferred losses in social good!

Second, achieving a decarbonized global economy as no longer primarily a technical, economic or financial question, it is political. As Al Gore loves to say, our capacity to survive climate change is all down to political will. And political will is a renewable resource.

Third, we need to proceed as though global health equity, sustainable development and the international policy response to climate change are inseparable. We cannot hope to cut emissions deeply enough on a global basis if the sum of our national greenhouse policies leaves billions with no prospect of poverty alleviation, and the poor health that attends poverty.

Fourth, we must make the most of the vital role the health community can play in tackling climate change. People have a justified tendency to respect their health professionals, as the response to the recent Ebola crisis showed. If the medics speak out, and act, positive change on the scale needed to defeat the climate threat becomes more likely.

Fifth, framing climate change as a health issue will help counter opposition from vested interests, accelerating progress towards meaningful action. Recently, for example, the British Medical Association joined the fast-growing divestment movement. Imagine you work for a fossil-fuel company, and you read in the papers that doctors now consider that you work for an industry on an ethical par with the tobacco industry. Is that likely to make you more or less likely to argue within your company for a change of business model to one that embraces energy transition?

I recently spoke with a senior executive in Statoil. She was ecstatic that her company has just set up a renewables division. Within E.ON, the first utility to change course and target all future growth on clean energy, staff morale has soared.

The Lancet Commission proposes a permanent international body to work on climate and health. Their project would be called "Countdown to 2030: Taking Action on Climate Change and Health". This multidisciplinary coalition of experts would monitor and report on the health impacts of climate change, progress in policy to reduce greenhouse-gas emissions, synergies utilised to promote and protect health, and progress in health adaptation action to reduce population vulnerability, to build climate resilience and to implement climate-ready low-carbon health systems.

How welcome such a development would be. During the course of my vocational life I witness, in microcosm, how impactful health-led climate-change abatement projects can be. SolarAid, a charity I founded in 2006, set up a retail arm, SunnyMoney, that has become the leading retailer of solar lighting in Africa, selling 1.7 million solar lights, most in the last two years, most in just two countries. Our detailed follow-up research on impacts in the field shows that these lights have improved the lives of ten million Africans so far. Over the three-year product lifetimes, we are in the process of saving $350m, creating two billion extra homework hours, and averting 890 tonnes of CO2 emissions. That is just where the social benefits begin, but let me focus on these three in turn to make my point.

On average, we find, a family in rural Africa saves $70 a year after buying a solar light. They recoup the cost of the light in 10 weeks and most commonly spend their savings on food, education costs, and farming inputs or business development further supporting livelihoods. All this spending promotes health.

Teachers tell us that they see improvements in concentration, attendance, motivation, and performance when a household has solar lighting. Evidence shows that when a child does well at school they are more likely to stay and attain a higher level of education. This is particularly true for girls. Increased levels of female education have a well-known positive impact on reproductive health.

As for the CO2 emissions cut by replacing kerosene use for lighting, this is a non-trivial increment in the sum of many increments needed to phase-out global fossil-fuel use. Fully 3% of global oil use is in lighting in the developing world.

And as with cutting fossil-fuel use elsewhere for purposes of greenhouse-gas emissions abatement, there are significant air-pollution wins. Nearly half of families in SolarAid's areas of African operations say they experience better health after using a solar light to reduce or end their use of polluting kerosene lamps. Respiratory disease from indoor air pollution kills more people each year than malaria, and kerosene lamps contribute to this, disproportionately affecting children as they sit close to the lamps to do homework.

The advent of a strong voice from the medical profession, in the push for a meaningful climate treaty at the Paris Climate Summit in December, is hugely welcome. It is part of a multi-sectoral mobilisation that is offering increasing hope around the world that humankind can see off the climate-change threat, and spin its collective response into a global renaissance. Projects like SolarAid give us a tantalising glimpse, in microcosm, of how this renaissance can happen, and the social good it will proliferate. All this I describe in my serialised book, The Winning of the Carbon War, available as a free monthly download, through to the Paris summit, on my website.