Vers une société résiliente au changement climatique / Building a Climate Resilient Society : colloque organisé dans le cadre de l’initiative « Avenir Commun Durable »
Conférence du 25 janvier 2024 : Climate Change and Health – From Impacts to Action
Session 3: Climate Change and Health
Intervenant :
Sir Andy Haines, London School of Hygiene and Tropical Medicine
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What I’m going to do is to give a very rapid overview of the impacts of climate change on human health and then say something about the actions that we need to take in order to protect Health as far as we can in the face of climate change and to capitalize on the
Healthcare benefits of moving towards a net zero carbon economy it’s a big topic it’s growing very rapidly there are conferences that last for several days covering all of these issues so I won’t be able to be uh comprehensive but I’ll try to give you an overview so this first infographic tries to summarize
This complex and and some cases evolving situation and at the top of the slide you can see how greenhouse gases are contributing to climate change causing um increasing temperatures of course changes in precipitation rising sea levels and then through a range of Social and other social economic and other environmental factors these
Modulate the way in which climate change is experienced around the world and the impacts it has on our health and through a range of different exposure Pathways these have impacts on health outcomes a range of Health outcomes and these range on the left from the most direct and obvious ones like the
Increase in heat related deaths particularly amongst the elderly not exclusively but particularly amongst the elderly uh obviously U it affects labor productivity as we’ve heard there are implications of wildfires increasing wildfires we’re beginning to understand that Wildfire smoke is damaging to human health probably more damaging than kind
Of average Urban Air Pollution has greater oxidative potential and increases the death rates from heart disease and respiratory conditions in the days following exposure also the effects on infectious diseases very wide ranging ranging waterbor diseases foodborn Vector born diseases and as we’ll hear later also um xonotic diseases those diseases
Transmitted from animals uh to humans undernutrition of course is a particular concern many parts of the world as a result of declining crop yields but also as carbon dioxide is put into the atmosphere that stimulates the growth of some crops but it also reduces the micronutrient levels so there’s a double
Whammy a double impact if you like reductions in the yield of crops but also declines in the nutritional quality of some crops reduced micronutrients which are a particular problem for many people living in low-income countries reduce protein content and and so on and then the effect on on Vector born
Diseases which I’ll mentioned uh in more detail and just just a moment a very wide range of vector born diseases we think of those in relation to low-income countries but that also affect Europe as well and then on the far right you can see the category which is most difficult
To quantify but probably the most important and that’s the effects on a range of social factors of course economic growth as we’ve heard displacement of population probably increase conflict again as we’ve heard so increasingly we’re trying to attribute the health effects to climate change in health uh to climate change to
Human induced climate change we’ve already heard briefly that attribution is a really important area for scientific research and the last review I read suggested there are about now 13 papers that attribute health effects to climate change so they distinguish between natural climate variability and human human induced climate change and
We’re increasingly able to attribute the health impacts to human induced climate change this is one example led by my colleague Anna visero Cabrera and uh what she did with very large group of researchers was to look at the attributable heat related deaths in recent decades that could be attributed
To human induced climate change using data from 43 countries and you can see that there are big gaps on the map there are big gray areas where we don’t have data much of subsaharan Africa much of Asia and so on but where we do have data
We can state that around about a third of the total heat related deaths over recent decades can be attributed uh to human induced climate change and this is a very active area of research you can see that temperature from this slide you can see that temperature um and mortality are
Differently distributed depending on where you are in the world and even within Europe you can see that there are big differences if you look at the top part of the slide on the right there in Stockholm actually not very big increases in cold temperatures or at hot temperatures probably because of the the
Housing uh and also because of the the local climate in Madrid there’s a much steeper u-shaped relationship um and also in in London we have high cold related deaths and very rapid increases in heat related deaths as well and the cold related deaths are partly related to energy poverty um and poor
Housing but it isn’t just human uh death rates that go up also affects particularly vulnerable groups we’ve already heard about the problems of Labor productivity but there’s one group that’s particularly vulnerable and that’s pregnant women subsistence Farmers we’re doing work with our colleagues in The Gambia and West Africa
Looking at the heat exposure of these pregnant women subsistence Farmers they don’t have a choice as to whether to work they have to work to feed their children and you can see the research team literally in the field with with the subsistence Farmers here measuring the wet bulb Globe temperature which
Integrates um air temperature with humidity and also with solar radiation through the black Globe which you can see at the top there on the left you can see the relationship between the wet Globe temperature and the fetal heart rate so the fetal heart rate goes up in direct proportion to the temperature
Exposure the heat exposure and we believe that has delerious effects negative effects on the fetus um and in some cases these heart rates are very high uh indeed into the level of kind of fetal distress and you can see on the right the kind of physiology of all this
Which I don’t have time to go into detail about but basically um the the the the woman’s hematological hematic H blood system is is attempting to redistribute the blood in order to reduce um the heat loading and that’s diverting blood from the placenta to the skin in order to
Increase um the heat loss and that de deprives the fetus We Believe of flood of blood essential um nutrients we also know that many other uh Pathways can affect human health as I mentioned earlier drought is one of them and we know that climate change increases the risk of drought uh the
Work of Freddy Otto and her colleagues has suggested that the the kind of drought we’ve seen in in the Horn of Africa and Somalia could be a 100 times more likely due to climate change because increased temperatures increase evapo transp transpiration that’s the particular driver and you can see that
Drought can affect Health through many many Pathways uh changes in infectious disas distribution of course uh changes in air pollution uh and changes of course in food availability leading to undernutrition so uh it can also stimulate of course migration so a range of different Pathways by which drought
Can have profound impacts on physical physical health but also probably mental health um as well as I mentioned in just a moment I mentioned um wildfires around the world increasing risks of cardiovascular or cause and respiratory mortality in the three days following exposure and in some cases these
Exposures are very very high indeed and you probably can’t see the map but it does show us the of red and orange circles where you get exposures of over 100 microgr per cubic meter so where we’re sitting at the moment I don’t know the exact exposure but it’s probably
Somewhere between 10 and 20 something like that so very very high exposures indeed for these short periods and although long-term exposure is more important for health these short-term exposures to particulates can also as I’ve shown have an impact on health Vector born diseases a lot to say there
I’ll just mention a few uh facts one is that the ability of these Vector mosquitoes Ed’s egypti and Ed’s Al pictus to transmit diseases like Deni has increased over recent decades as shown in this paper from my colleagues at the school Chris Murray and others and you can see how the victorial
Capacity the ability to transmit Deni has increased over recent decades that’s not just a problem for the tropics and subtropics we’re also seeing Ed ala pictus in Europe we’ve seen Transmission in France for example in madira and it seems to be spreading the vector seems to be spreading north um and west with
Climate change it’s not the only Factor but it’s an important factor also and I think we’ll hear more about this later but these zoonotic diseases emerging zootic diseases may also increase probably as a combination of uh decreasing uh biodiversity changes in land use and climate that forces together animal species in smaller areas
Of land supporting and increasing the transmission of viruses between different animal species and between animals and humans particularly where we’re seeing urbanization rapid growth in urban populations overlapping uh with this uh increase in transmission as you can see in the purple areas of the map here where the transmission is likely to
Be greatest including parts of Africa parts of Europe North America uh South Asia of course and and parts of Latin America also there’s a link between ocean Health and Human Health which we’re beginning to understand more about this is just one example from from Europe which shows you how the coastal
Waters which with environmental conditions that are suitable for the transmission of vibrio species vibrio obviously vibrio is is a big killer around the world these are not CH vibrio but they can cause adverse health effects and you can see I think from the color on the map that in the Baltic and
In the black Black Sea you can get increasing um transmission of these vibrios pieces if you bathe in this water uh and in some cases that can cause quite some serious health outcomes particularly for people who are who are immunosuppressed so we are seeing this relationship this growing awareness of
The relationship between ocean um and human health and in Bangladesh there’s increasing saltwater intrusion so probably it’s not just due to sea level rise in Bangladesh it’s also due to the local environmental challenges of damning of rivers for energy and for shrimp farm and other things and we’re
Noticing that this is a papers by our colleagues led by colleagues based in Bangladesh showing relationships between drinking water sodium and blood pressure in both pregnant and non-pregnant people and we’re seeing in pregnant women an increased risk of preclampsia which of course um conveys an increased risk of
PR adverse pregnancy outcomes so this is the kind of thing we would expect to increase more as sea levels rise I’ve mentioned the effects of food climate change on on food we’ve heard it from other speakers as well we tend to think of that as a problem for low
Income countries but it could be a problem for Europe as well and one reason why that’s so is also is shown in this slide which shows you the increasing dependence of the food supply in the UK this is particularly fruit and vegetables um on climate vulnerable countries so if we increase import our
Imports from these countries as they start to Bear the Brunt the impacts of climate change then our food supplies may be increasingly affected now fruit and vegetables are very important for human health because you need an adequate intake of fruit and vegetables to reduce your risk of cardiovascular diseases and other
Non-communicable diseases so you need about 400 grams a day uh for Optimum effect it’s not just physical effects it’s also mental health effects as well of climate change and we’re realizing that climate change can have a range of mental health effects because of exposures to floods droughts wildfires when you follow these
Populations up for a year or so you find quite long-term effects increasing anxiety uh and depression post-traumatic stress disorder and so on and also shown on this slide on the right side you can see the results of recent surveys of climate anxiety amongst children and
Young people this is a study in I think 15 countries showing pretty high levels of climate anxiety and the gray bars show you the impact on functioning so overall about about 45% of these young people said that the effects on their mental health was so M so much that if
Interfered with their functioning um as as as people they were had these pervasive worries and anxieties about the climate so it’s having an effect on mental health now particularly uh amongst the young so we need to act promptly quickly as we’ve already heard and we need to both adapt to the climate
Change that we can’t prevent to reduce the effects on health well-being and the economy but also to mitigate to C cut emissions and we need to do both simultaneously we tend to think of adaptation and mitigation of separate activities but we actually need to integrate as we’ve already heard uh
Adaptation and mitigation to avoid Mal adaptation one example might be air conditioning of course you can put air conditioning everywhere but if you do that you increase your burning of fossil fuels in many countries increase air pollution because of that increased burning of fossil fuels you also have to
Put the heat somewhere so you Pump It Outdoors so when you go out of the buildings you actually exposed to Greater heat the greater Urban heat island and of course it increases uh inequalities as well because the poor cannot afford air conditioning so we need to develop better early warning
Systems for climate events but also to cut emissions and in cutting emissions we can really benefit um human health and I’ll mention that in just a moment but let me just say a word about adaptation there are growing literature on how we can adapt to climate change to prevent adverse health effects through
Better early warning systems on heat on Vector born diseases this is just one slide showing work by our colleagues Philipe colon Gonzalez and others um using um model climate forecast using um a super Ensemble of probabilistic models to predict Deni risk and this is in Vietnam but they’ve been working in a
Whole range of different countries and they’ve shown that using these seasonal climate forecast You can predict the risk of Deni and then you can put in place Public Health interventions to reduce the risk that’s just one example of adaptation but there’s also big opportunities of mitigation um so these are co- benefits
So-called Health co- benefits of mitigation they ancillary benefits of mitigation they’re near-term benefits and then in addition to the benefits of reducing the risk of dangerous climate change and the reason for that there are three big Pathways reductions of fossil fuel related air pollution improvements of physical inactivity through improved Transport
Systems which give people the opportunity to be physically active reduce air pollution exposure and diet of course and I think Charles be talking about diet so I won’t say much about that but the eat lanet commission has suggested that we could could reduce um uh premature deaths by perhaps by over
10 million per year by shifting to healthier diets now you may say well these are rather exaggerated projections they depend on dramatic dietary change but they give you an indication of the kind of magnitude of effect so millions of deaths from uh air pollution from fossil fuels a recent estimate we just
Updated that led by our colleagues at the max plank Institute for chemistry in mines in Germany we suggested over 5 million deaths year per year many of these in India and China but also in high income countries too hundreds of thousands overall physical inactivity about 4 million and as I’ve said over 10
From diet so big potential benefits if we could realize those benefits and we’ve just published um the output of our Pathfinder commission which I have the honor to co-chair with Helen Clark and joy Fu mfy who you may be aware of and this is an initiative which is
Really trying to synthesize all the evidence that we have about the health co- benefits of climate action and what we found is that about 90% of the research is from modeling studies which are modeling studies very important of course but they don’t tell you what happens when you try to implement change
And only a small proportion of the studies are implemented actions where they measure greenhouse gases and measure Health exposures or outcomes and this is the evidence bank that we’ve created which is open access you can anyone can access it and look at um the evidence that we’ve found and we
Basically confirm that there are big potential health benefits but the challenge now is to implement these benefits also um a couple of years back the Royal Society and the Academy of Medical Sciences in the UK supported this uh report which looked at how we could achieve the health Co benefits but
Also avoid some of the trade-offs uh from Net Zero policies in the UK there are a few trade-offs for example as I’ve mentioned air conditioning might be one uh another might be if we seal up buildings if we insulate buildings very tightly that improves the Energy Efficiency but it can also increase the
Household air pollution exposure so you have to be aware of these trade-offs in order to capitalize on the co co- benefits and this report summarizes the situation for the UK there was also an air pollution report from the Royal Society and this looked at the air pollution benefits from different Net Zero
Policies on the right the Green Arrow shows you better air quality and on the left shows you poorer air quality and you can see that most of these policies result in improved air quality some of them could have negative effects depending on how they’re implemented bioc crops for example
Burning of biofuels could increase air air pollution um car carbon capture and storage depends on the technology you use and on the assumptions that you make but overall many of these policies um are win-win so there’s reduced um air pollution better air quality and reduced greenhouse gas emissions but of course
The key as we’ve already heard is to implement these policies and we’re often not doing that at the necessary speed and scale particularly in the food system um house household energy buildings and so on is particularly as we’ve heard from um from Brown already we tend to think of course of air
Pollution mainly from fine particulates and that’s correct it’s mainly fine particulates that cause the damage but also um ozone is another important air pollution and although methane is a powerful greenhouse gas it doesn’t cause damage to human health directly but it is an ozone precursor and tropospheric ozone causes hundreds of thousands of
Deaths per year around the world some estimates suggest perhaps over a million premature deaths and methane’s responsible for about half of these deaths so by reducing methane from changes in agriculture food system um gas leaks fossil fuels and so on we can improve human health and also
Improve um crop crop yield as well because tropospheric ozone is damaging to crops so we’ve just done a study a year or so back um published um looking at the health benefits of Net Zero policies according to the committee on climate change projections in England and Wales
And we’ve shown that you could get something like um an extra 2 million years of life over coming decades by following the committee on climate change balanced uh Pathways scenario and even more if you go to the widespread engagement scenario about um an extra 25% something like that and these
Benefits as you’d expect are from reduced air pollution including in the household um improved diets increased physical activity from more for walking and cycling and the use of public transport so there are substantial benefits in a country like UK and then finally in conclusion my last slide I
Don’t want to completely omit the Health Care System itself we are now beginning to understand that the healthc care system is responsible for about four to 5% of greenhouse gas Emissions on a global scale in the US it’s more than that it’s about over 8% because they have a very energy
Intensive health care system with strong dependence on tertiary care and so on about to 60% of these emissions come from the scope three emissions which are shown on the right side of the slide here uh these are the emissions which are embedded in Pharmaceuticals in medical equipment and so on which are
Very energy intensive to produce so it’s not just a question of decarbonizing the energy Supply it’s also a question of working with the pharmaceutical industry the medical equipment industry but also um embarking and emphasizing ing the importance of prevention so I’ve mentioned the benefits of moving towards
A net zero economy and that could at least in theory help to reduce the burden on the Health Care system so we’re now seeing a lot of activity by who and others to bring together a coalition of Nations to uh move towards more climate resilient Health Systems
But also um in a number of cases moving towards net zero Health Systems including um in the UK so I’ll stop there but just want to emphasize the fact that climate change does have wide ranging effects dangerous and negative effects on human health but there are big benefits to adapting to and to
Mitigating climate change thank you very [Applause] Much