Taking on the unknown unknowns

As the world looks to the UN and their meeting on climate change in Paris next month, nothing less than the fate of our future health is in the balance says Peter Byass

As a public health researcher in an increasingly interdisciplinary world, I sometimes feel quite envious of scientists whose research fits neatly within the confines of a laboratory bench. I don’t mean to imply that lab research is easy – but at least in the lab the potential effects of all sorts of unknown global forces can generally be controlled. Any kind of population-based health research, however, shifts the scientific considerations into the realm of real-life issues and variabilities, which can be difficult to understand even in the most rigorous randomised controlled trial environments. But if we move on to an interdisciplinary mix of climate change and public health science, the unknown unknowns really take on a life of their own.

So why try to do anything at all around this complex nexus of climate and health? The world’s seven billion people inhabit a fascinating but fragile biosphere – the thin layer around the surface of the planet – which for millions of years has been a constantly changing zone but has remained within limits that have been consistent with the survival of a staggering diversity of life-forms. I am not a climatologist, and I would not presume to get into considerations of what may happen to the Earth’s biosphere in the next million years or so. But what I do know, as a health researcher, is that every living creature is somehow dependent for survival on the physical environment it finds itself in, and this applies not least to Homo sapiens.

Unpacking the meeting point between climate and weather is important here – and it basically comes down to a question of time and place. Yesterday’s weather wherever I happen to be is pretty much now a matter of fact. Today’s weather is an evolving situation, but the clues of present experience are very informative, and uncertainties are fairly well constrained. Moving on to tomorrow and beyond gets much more difficult, as weather forecasters well know. Climate takes the long view, however – what has the weather been like over centuries, and what is likely to happen in the decades and centuries to come? Nevertheless, weather and climate are not independent concepts. Much of the short term fluctuations that we call weather are driven by thermal energy contained in the biosphere. If the biosphere’s energy content increases (which can be measured by long-term changes in average temperatures), a consequence is that local short-term fluctuations can become more energetic. That in turn means that “rare” extreme weather events may become less rare after all. An interesting example was the floods in Cockermouth, in northern England, after over 300mm of rain fell in a very short period in November 2009, and stone bridges that had stood for centuries were washed away.

The recently published Lancet Commission on Climate and Health¹ sets out in great detail some of the possible interactions between climate and health, covering both potential detriments and benefits. It would be wrong to pretend that it is possible to exactly understand all the ways in which climate and weather have affected, are affecting, and will affect human health on a global basis. The required data, theoretical frameworks, and computational capacity are simply not there. Nevertheless, there are enough observations to demonstrate beyond reasonable doubt that the health consequences of weather and climate change need to be taken seriously.

With an interdisciplinary mix of climate change and public health science, the unknown unknowns really take on a life of their own.

In an article accompanying the Lancet Commission, Ethiopia’s Ministers of Health and Environment draw attention to some of the consequences for their country and citizens². Ethiopia is one of the world’s fastest growing economies, but recognises the need for sustainable growth within a green framework. Water and energy supplies are critical to growth, particularly in equatorial Africa. At the same time, vulnerability to weather is a well-known part of Ethiopian history, with memories of devastating famines in the past. More recently, high-mortality outbreaks of infectious disease have been associated with aberrant weather patterns³ and childhood nutritional status has been correlated with weather⁴.

Nevertheless, the Lancet Commission is optimistic about the potential positive interactions between climate and health – the so-called “co-benefits”. The principle here is that actions can be taken at the individual level which are beneficial both to the health of the planet and to personal health. One obvious example is around the choice to walk or cycle to work, rather than using motorised transport. The climate benefit of walking or cycling comes from the resulting reduction in CO₂ emissions, while the personal benefit comes from the extra exercise involved. The public health community knows very well that behaviour change is often easier to suggest than achieve, even for an individual, never mind entire populations. However, the conclusion is that current popular concerns around climate change may also be a global opportunity for better individual health.

Possible threats and concerns arising from climate change have recently come into the public arena very visibly, with President Obama⁵, Pope Francis⁶ and the Governor of the Bank of England⁷ all making important statements. Meanwhile, a very small, but often very vocal, minority continues to contend that the unprecedented volumes of greenhouse gases being discharged by humankind into the biosphere are of no consequence. In December 2015 the United Nations will hold a major scientific and political meeting on climate change in Paris, at which it is to be hoped that world leaders will move towards useful and meaningful agreements on emission control and reduction in fossil fuel consumption. From a political perspective, it is unfortunate that the science points to the need for decisive action in the relatively short term in order to avert longer term detrimental consequences. Drawing politicians’ attention to issues that will impact after their terms of office expire is always hard work. It is to be hoped that the Paris meeting will manage to take the longer, more scientific, view.

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The author: 

Peter Byass, Director, Umeå Centre for Global Health Research, Umeå University, Sweden