(Source: Flickr/USAID Kenya)
The evidence for climate change is compelling: during the last decade we have experienced eight of the warmest years on record. Global surface temperatures are predicted to rise above the 2⁰C threshold – and possibly dramatically so – within less than a century.
But what does that mean for health? I recently attended a discussion by speakers Hugh Montgomery, Ian Roberts, Anthony Costello and David Satterthwaite, experts on different aspects of health in a warming world.
They discussed current climate science, current and projected impacts on health – through extreme events and threats to shelter, food and water security, ecosystem and economic stability – and health co-benefits.
Vector-borne diseases, which are transmitted by insects and mites or ticks, including serious diseases like malaria and tick-borne encephalitis, were not discussed much, but they have strong associations with the climate and are clearly an important influence upon global health.
They account for 16% of the estimated total global disease burden for all communicable diseases and the majority of Neglected Tropical Diseases (NTDs) – diseases that affect a billion people, yet receive comparatively little attention or funding.
Also of importance is how climate change can impact directly upon these diseases, because of their strong associations with poverty and the effects climate change has upon economic stability.
Climate also impacts upon food and income generated by livestock, via diseases such as African Horse Sickness and Bluetongue, therefore further affecting economic stability.
The predicted escalations in temperatures, precipitation and humidity will influence both intermediate host and vector ecology and biology, and also interact with other factors like urbanisation and increasing volumes of global trade, making the influences on transmission dynamics very difficult to predict.
What is clear is that they are potentially very large, making a strong case for a precautionary approach.
In a warming climate, a number of mosquito species can develop and reproduce faster, which can increase population growth and biting rates, and therefore the transmission of diseases they carry, such as malaria, dengue and yellow fever.
Rainfall is also important. During the 1997-1998 El Niño, precipitation shifts led to explosions in mosquito populations, evoking epidemics of the most dangerous species of malaria.
Areas that receive less rain could also have negative impacts on vectors: Anopheles funestus mosquitoes for example virtually vanished from Senegal due to reduced precipitation rainfall, resulting in a 60% reduction in malaria prevalence during 1970-2000 in Senegal.
However, changes in ecosystems which negatively impact one vector species can benefit others. In a dryer, warmer environment, a species of Tsetse fly which thrives in dry savannah regions and is responsible for spreading a particularly virulent strain of sleeping sickness, is predicted to increase.
Indirect environmental factors
Changing ecological factors, including but not limited to climate, can create new selective pressures on vectors: for example, deforestation and increasing urban sprawl have most likely contributed to the vector for Chagas disease, becoming adapted to feed on the blood of encroaching human populations.
It has shifted from a diet primarily involving wild animals to one where it feeds primarily upon people in their own homes, and so increasing disease prevalence.
And the problem is not confined to developing countries: warmer winters have enabled the Asian tiger mosquito to establish itself in Italy, presenting serious potential risks of dengue.
Tick-borne encephalitis and Lyme disease could also be supported throughout Europe by thriving tick populations. In addition, globalisation and increasing rates of air travel put us all at risk of emerging and re-emerging infectious diseases even if they first manifest themselves in populations on the other side of the world.
The short- and long-term consequences of climate change will ultimately influence the ecology, transmission, dispersal and evolution of a range of vector-borne diseases across the globe in important ways. These will interact with many other impacts, such as economic effects and population displacement to result in direct and indirect health impacts.
The most obvious corollary of this story is the need for rapid and urgent action to mitigate climate change.
Nevertheless, we also urgently need to prepare more effectively for unavoidable infectious disease risks associated with climate change: modelling to predict potential threats, vigilant surveillance and epidemiology, and adequate, well-targeted funding will all be essential for effective and efficient disease prevention and control strategies.
Originally published at
The direct impacts of natural – and, in a warming world, (un)natural – disasters are relatively straightforward to quantify.
They are also probably some of the easiest health impacts of climate change to evaluate (albeit with the caveat that we can only attribute trends to climate change, not single extreme weather events).
The deaths and injuries, and the epidemics that can happen in the wake of a flood or hurricane are in some ways more easily attributable than the impacts of extreme heat, or those of air pollution exacerbated by a heatwave.
Even so, the effects of extreme weather events on health, especially the longer-term impacts, can be difficult to evaluate fully.
Often they’re not the things we think of straight away: carbon monoxide poisoning or exposure to cold and mould for example, leptospirosis (an infection spread by rats) or even allergic reactions to bee and wasp stings, which have been shown to increase after hurricanes and flooding.
Then there’s what happens when the medical services are overwhelmed or a power outage makes storing drugs difficult. Pre-existing conditions often aren’t properly managed and deteriorate at that point, putting peoples’ health in danger further.
In addition to deaths from drowning and the physical health impacts of injuries, hypothermia, water-borne diseases etc, extreme events can also have severe and long-lasting effects on psychological wellbeing.
A month after Hurricane Katrina, 17% of residents reported signs of serious mental illness – compared to a general population average between 1 and 3%.
Equally important to bear in mind is the importance of inequality, which is a recurrent theme in practically all research and literature on climate change and health. In the parts of the world where the biggest impacts from extreme weather events occur, generally those least responsible for causing climate change, there is often far less surveillance or data collection capacity and infrastructure to be able to assess the extent of impacts accurately than where we have more adaptive capacity and are better prepared.
In turn, this means we may well be underestimating the true, global extent of the health effects of such events.
To take a recent illustration of these themes, Hurricane Sandy caused at least 71 deaths in the Caribbean and approximately 100 in New York, and had immense and devastating impacts on the economy and on peoples’ lives, which are still continuing for too many people.
Had it made landfall somewhere poorer such as a Central American country, the death toll could have been significantly higher. Most likely it would also have received less coverage had it hit a poor country.
The side of Sandy that we heard much less of in the international media was the fact that it left 21,000 Haitians homeless and 1.5 million in a situation of severe food insecurity. Many of these were already in an extremely vulnerable situation after the 2010 earthquake and tropical storm Isaac two months prior to Sandy.
After Sandy, Congress approved a $9.7bn aid package, and has more recently approved $50 billion. On top of that, $854m was pledged by the international community.
Compare that to 1998’s Hurricane Mitch in Nicaragua, where around 3800 people died (of 11000 total across Latin America) and more than a million were left homeless. In total, the aid received was just over $118.5m, based on the sum of the Secretariat of External Cooperation and the Red Cross Federation’s total figures.
Although the scale of need was arguably much greater, total funds were around 100 times lower than even the early US aid package for Sandy and nine times less than the international pledges made, including by countries as poor as Afghanistan and Uganda.
A recent report found that the total impacts of climate change on the global economy are of the order of $1.2 trillion, as well as contributing to 400,000 deaths. But determining and predicting the role of climate change in the spread and emergence of new or re-emerging infectious diseases is significantly more complex, especially when we try to integrate the effects that extreme events can have on infectious disease patterns, often in unpredictable ways.
In turn, investigation of how extreme events affect food and water security or – even less directly, economic stability or conflict – is even more complex. I find it helpful to think of climate change as a threat multiplier rather than a causal factor, but it is the extremes where the real health risk, and the real unpredictability, lies.
The causal chain is so much more complex, and the effects less easily demonstrable, yet these could potentially have much bigger effects on health, than the more direct impacts.
Although hurricanes aren’t caused by climate change as such (see the IPCC’s report on extreme weather) there is good evidence that when they do occur such storms are made stronger by its other effects.
Rising temperatures mean more moisture in the atmosphere – for every 1°C rise, air can hold 7% more moisture – resulting in much heavier rain. Climate change also drives rising sea levels and so an increased risk of storm surges.
The global sea level has risen approximately an inch in the last decade alone, which further increases the threat when landfall coincides with an extra-high tide, as in the case of Sandy, and flooding can start even before landfall.
The Weather Channel’s senior meteorologist Stu Ostro said Sandy represented “a meteorologically mind-boggling combination of ingredients coming together…an extraordinary situation.”
The odds are that it has made ones like Katrina and Sandy more severe than they would have been without it – yet in the sort of irony you really couldn’t make up, $400m of the international pledges made, were offered in oil.
Events like these are also part of an ongoing trend of more frequent and more extreme events in recent decades: this series around the globe last year, taken together, are unprecedented in their size and frequency.
The health effects of extreme weather can be severe, even in rich countries, and much worse in poor ones: we can’t afford to hope they’re all just coincidences, and we can’t afford to wait.
The military supply water in Dhaka (Source: UN/Kibae Park)
Originally published at: http://www.rtcc.org/2013/05/27/comment-health-overlooked-in-our-response-to-climate-change/
The protection of human health and wellbeing is a central rationale for the emissions reductions called for in the very first article of the UN Framework Convention on Climate Change (UNFCCC). Yet, somehow, the issue is missing from many parts of the UN talks.
The growing body of research and evidence in the area over the past couple of decades hasn’t really translated into a broader understanding of how climate change and health are related, beyond a relatively small community of academics and health professionals.
Knowledge about the links between climate and health among the public, climate negotiators and environmentalists is often limited and quite superficial. It typically doesn’t stretch far beyond the more direct impacts, such as heatwaves, vector-borne diseases or extreme weather events such as flooding.
Indirect effects on health are rarely considered, and both the media and the public tend to frame the impacts of climate change in terms of the risks to ecosystems and species or economic losses; very rarely in terms of its other impacts on people and their health.
Perhaps this is part of why climate mitigation and adaptation measures fail to get the levels of both political and financial support they need to tackle climate change and to protect and promote health in the face of it: current levels of adaptation finance, much like current emissions reductions pledges, are grossly inadequate.
As a glance at any newspaper or polls about the relative political importance of different topics make clear – most of us are concerned about our own health and the health of those we care about, including that of our children and grandchildren and less visible problems like climate change, which are also delayed in time, often feature far below this on the agenda.
Climate change will dramatically affect the health of today’s children and young people, and more than that, policies to promote the health ‘co-benefits’ of sustainability and climate action could greatly improve health.
Surely those messages, if communicated more effectively, could be a strong driver to help us achieve the sort of rapid, meaningful changes we need in order to avoid catastrophic climate change - couldn’t they?
In the UK, several thousand health professionals have joined the Climate and Health Council to add their voice to a global climate and health movement which already has strong voices in Australia, Europe and the US, along with several other regions, and they are starting to connect up, for example with the Doha Declaration.
Doubt is their product...
At the same time, communication with negotiators, the mainstream media and the wider public around what’s known about climate and health clearly hasn’t yet been very effective, and has been compounded by the confusion that biased and inaccurate media such as Fox News and the Murdoch empire seek to create. This is very much like the 'merchants of doubt' phenomenon that emerged among tobacco companies as the evidence of tobacco's health risks came to light.
One of my friends recently asked me when he saw this video, “if climate change is really such a big health threat, then why don’t most people know that, and why isn’t it mentioned more in the news?”
I’m convinced by the evidence that it is – some of it is collected in our resources section– but I found it hard to answer his question. Have we all, consciously or subconsciously, decided that it’s too depressing so we don’t want to know, do the media decide it’s not worth broadcasting, is it related to the success of fossil fuel companies and their PR and lobbying teams, or is it something else?
I don’t have the answers, but I think there are many reasons: for one, picking out long-term trends to ascertain what health impacts are attributable to climate change is no easy task, and – especially when it comes to modelling future health impacts which are often highly dependent on socioeconomic factors too – the science is far from simple.
Predictions, of necessity, depend on various assumptions and on multiple interacting factors. As with climate change in general, the real-world effects are highly uncertain: not because scientists think health might be fine in a world four or six degrees hotter, but because it’s very hard to work out exactly how bad the impacts may be.
Even the World Bank now explicitly recognises that this is what we’re currently on course towards, that it’ll be far from easy to adapt to, and that such a temperature rise would conflict greatly with its mission to alleviate poverty.
The dangers of ignoring Black Swans
As George Monbiot pointed out in characteristically optimistic style last year, mainstream global predictions for future food availability in the face of climate change may be wildly off – because they’re based only on average temperatures rather than the extremes. A fatal error if this is true that the extremes – droughts, wildfires and so on – could become the main determinant of global food production, interacting with other changes to affect in ways that, like Taleb's 'Black Swan' events, are almost impossible to predict.
If this does turn out to be the case, it’s likely that by far the biggest health impact of climate change will be malnutrition, as argued by Kris Ebi, lead author of the human health section of the last IPCC report. Inadequate food intake not only increases vulnerability to infectious diseases such as malaria, TB, pneumonia and diarrhoeal disease, but also kills directly through starvation.
Food insecurity, in turn, can force people to migrate just as something more obvious like sea-level rise can, and this can be a driver of civil conflict. Both migration and conflict of course have major physical and health impacts, but their extent and distribution depend on numerous other things; climate is one driver among many. Like any give extreme weather event, it’s hard to attribute indirect effects of climate change such as these to climate change, given how strongly it interacts with other contextual factors. But that doesn’t mean it’s not a causal relationship.
As the Millennium Ecosystem Assessment showed in 2005, our health and wellbeing ultimately depends on ecosystem functioning and stability, at levels from local to global. How ecosystems and in turn health are being – and will be – affected by climate change is unavoidably complex. That makes it hard to communicate and hard to use to change policy, but we cannot allow this to stop effective advocacy and action.
The fossil fuel industries and the many dubious institutions and individuals they fund will not wait: with billions made from the sale of coal, oil and gas, they are much better organised and resourced than us at present, and they will use every opportunity to maintain doubt, prolong inaction and ensure that our future isn’t allowed to compromise their sales.
In order to extend a sense of the importance of climate action beyond the environmental community and to secure broad and deep consensus on the need for concerted action, health must play a much bigger role in decision-making at all levels. Both impacts and health co-benefits need to feature more centrally in national mitigation and adaptation plans, and in our discussions around climate change more generally.
That shift won’t happen on its’ own, and with the Bonn UNFCCC intersessionals coming up in June, it strike me that health should be a priority. Better resourcing and a comprehensive work programme including capacity-building, education and raising public awareness on subjects specific to climate and health would be a tangible and positive way to protect and promote health and to reduce the impacts of climate change on the most vulnerable.