"The impacts of climate change on health are large and they are going to be bigger as we go forward," says Andy Haines on new IAP report

The project has produced four regional reports for Africa, Asia, the Americas and Europe. Are there main findings that relate to all these regions?

Of course all regions are being exposed to climate change. They have different epidemiological patterns, patterns of disease and health. And they have different supply chains, different challenges with regard to food, crop growth and so on. But there are certain commonalities: issues like extreme heat may be experienced more in some regions than in others. But they are experienced widely in all regions. We also see wide-ranging evidence that infectious diseases, like for example vector borne diseases transmitted by mosquitos and other disease vectors, are changing their distribution and increasing incidence in different parts of the world.

Additionally we know that many populations are being increasingly exposed to extreme weather events, like floods, heatwaves and droughts. And although these have different magnitudes of impact in different regions, nevertheless all regions are exposed to these extreme events related to climate change. So although there are regional differences, there are also commonalities and we have to remember that no part of the world can be insulated from climate change. We are all being affected by climate change to some extent.

Your goal was also to describe significant variation within and between regions. What are your main findings regarding these regional specifics?

These differences within regions and between regions are quite complex, therefore I would like to give you a few examples: the Arctic region for example is heating up faster than many other parts of the planet. So we are seeing in the Arctic region important impacts on human health with regards to changes in disease transmission, more accidents and extreme events related to melting of the ice for example. Some communities are experiencing displacement. In other parts of the world we are seeing very large wildfires in places like California, in Australia and so on. And these wildfires have very important implications for human health, not just the smoke from the wildfires – that increases the risk of death due to cardiovascular and respiratory disease in the days following the wildfire. But there are also long term mental health effects of wildfires and many other extreme events.

And then there are parts of the world that of course are beginning to suffer from effects of climate change on crop yields. This is particularly the case in tropical and subtropical regions, but also in other parts of the world as well; and this will increasingly impact population health over the decades to come. So there are differences as I have said, but there are nevertheless many commonalities between regions.

There are other international assessments of these issues e.g. recently the 6th assessment cycle of IPCC. How does the work of IAP and its regional networks add value to these other assessments? 

The added value of the IAP exercise in addition to the IPCC – which of course is a very important international process – is that it engages a wide range of science academies around the world in different regions. So this is a unique opportunity to engage not just the health community but also scientists from other disciplines who are represented in the member academies of the IAP. And this I think gives voice to countries and to disciplines that may not always be heard in some of these other international assessments. So we hope that it really gives a very wide geographic and disciplinary range of different perspectives on this important transdisciplinary challenge of climate change and health.

Which diseases can be attributed with high probability to the ongoing climate crisis? Which diseases are still under scientific discussion in this regard?

There is a lot of work going on regarding climate change effects on different diseases. Historically climate and health research has been starved of funds. But now there is an increased interest in this area and gradually we are seeing more evidence coming on stream. So there is good evidence that the risks of extreme heat are increasing due to climate change. A recent study based on data from 43 countries and over 700 sites shows for example that about a third of the heat-related deaths over the recent decades in those countries can be attributed to climate change. We are also seeing changes in the distribution of vector-borne diseases, diseases such as dengue – a very common disease transmitted by mosquito vectors. We do know that although mosquito control programmes are successful in parts of the world, nevertheless climate change has increased the capacity of these vector mosquitos to transmit the disease probably by about 10 percent so far, but obviously it is likely to go up in the future.

And then of course we are increasingly confident about the mental health effects of climate change because so many people are being exposed to these extreme events like floods, droughts, wildfires and heat waves themselves. And these can have effects not just on physical health but also on mental health. 
Currently the evidence of climate change impacting health is still patchy in some areas – Africa for example. Sub-Saharan Africa is really underrepresented in many of the studies. So there are still quite big gaps in the evidence, but it is building steadily and sadly we are increasingly confident that climate change is having an impact on human health now and will do so even more in the future.

How many people's health is directly or indirectly affected by the climate crisis worldwide and who is most vulnerable? 

In terms of giving numbers, there is still a lot of uncertainty about that. The WHO estimates about 250,000 extra deaths annually between 2030 and 2050, but that is quite a major underestimate as WHO itself recognizes because it is based on a very limited number of health outcomes. Another study estimates half a million extra deaths by mid-century just from the effects of climate change on crop yields. And that may itself be an underestimate. So, the impacts are going to be large and potentially catastrophic as we go forward unless we take really decisive action in the next few years to reduce the risks of climate change on health.

We know that billions of people are increasingly vulnerable to climate change impacts. For example, over time it is becoming increasingly difficult to work due to the increased heat. When you are exposed to extreme heat, the body has real problems in regulating the internal core body temperature. And that impacts on the ability to work. So by the time we reach 2.5 °C increase in temperature – which could happen later this century in the absence of effective action – then a billion people or more could be exposed to such extreme heat that it would be hazardous for them to work during the hottest month or so of the year, even in the shade. So that just gives us an idea of the kind of magnitude of impacts that will have major effects not just on their health but also on their ability to earn money, to grow their crops – many of them are subsistence farmers. 

The IAP's Global Report says that extreme weather events linked to climate change are hitting humans and other species much harder than previous assessments indicated. What does that mean?

Scientists are increasingly confident that we can attribute certain events to climate change and not just to natural climate variability. If we take for example the Siberian heat wave of 2020: That heat wave in Siberia was an extraordinary event and it was almost impossible in the absence of human-induced climate change. But not just heat, also flood events and increasingly intense rainfall events. As we heat the atmosphere it holds more water and therefore the precipitation events become more intense. And we know that both floods and droughts have many effects on human health, not just infectious diseases, but also mental health as well. 

So there is building evidence about the impact of these extreme events on health and also the extent to which they can be attributed to climate change. 

The decarbonisation of energy systems would lead not only to less CO2 emissions but also to less air pollution. How would this effect people’s health?

Air pollution is at the moment a very major killer. The World Health Organization’s official figures are 7 million premature deaths a year from a combination of ambient – that is the environmental or outdoor air pollution – and household air pollution. Fossil fuel burning is the major contributor to ambient air pollution from human activities. Household air pollution  is mainly a problem in low income households that burn solid fuels. Air pollution increases the risk of heart attacks and stroke. It effects people’s lungs, increasing the risk of pulmonary disease and a range of other health outcomes. Thus fossil fuel burning is a major driver of climate change and is also causing major health effects now through air pollution. In particular very fine particles that can penetrate very deep into the lungs, and even get into the blood stream – these have wide-ranging effects on human health.

As we move towards a zero carbon economy in phasing out fossil fuels, we can expect to reap the benefits, not just from reduced risk to dangers of climate change but also the reduced risk of air pollution to our health. So it is a win-win situation: cut fossil fuel burning, reduce climate change, reduce air pollution and improve health in both the near term and the longer term.

The regional and global reports from the IAP project call for better integration of mitigation and adaptation solutions. Do you have examples?

It is a really interesting challenge as there are these two different policy responses to climate change: how can we adapt to the climate change that we cannot prevent? And remember – we are already at 1.2°C global average temperature increase. And then how can we mitigate, how can we cut emissions to reduce the risks and dangers of climate change in the future? Now these two policies often work rather independently and perhaps the people involved in them are often quite independent. Those concerned with adaptation  are involved in natural disaster preparedness and so on. The mitigation actors are more involved in energy policy, built environment, transport and increasingly food systems as well. But there are some policies that will bridge both, for example some nature-based solutions. Nature-based solutions are those policies that support nature, biodiversity,  greening of cities and infrastructure as well as reducing risks of climate change. So those nature-based solutions combine both adaptation and mitigation. One example would be the increasing green space in cities. Green space is obviously important as we all enjoy being in a green space, besides it also helps to cool cities. And cooling cities helps us to adapt to climate change – but it also reduces the power demands for air conditioning. If you just put in more air conditioning, you have got to burn more fossil fuels – our current energy sources – to generate more energy to power the air-conditioning. So having natural approaches to reducing temperatures, through green spaces, through passive ventilation systems, is a good way of both adapting to and mitigating climate change.

The now released "Global Synthesis Report" shall also provide advice for decision makers for implementation at global, national and regional levels. In your reports you call for urgent action. What are your demands precisely?

Urgent action is required because we have to, as I have said, adapt to climate change that we can’t prevent, but also cut emissions. And we have to cut emissions very quickly. Certainly, that 1.5°C target that is in the Paris agreement is rapidly slipping away from our grasp, very sadly. If we are decisive, if political leaders are decisive we can still keep under 2 °C which hopefully will protect us from the worst impacts of climate change. So cutting GHG emissions is an urgent priority and it is the responsibility of the high emitting nations to cut theirs rapidly and to show leadership in this respect. That will produce health benefits both in the near term and the long term. So using the health argument for accelerating the transition to a net zero carbon economy, we think is really important – an urgent goal that has to be achieved.

Another issue is mobilising the health care professions and getting better data on climate change impacts. We strongly recommend monitoring and surveillance so that we are not caught unprepared, so that we understand the impacts of climate change on health as they are happening now in our communities, especially in vulnerable communities. We often forget those in monitoring and surveillance systems. But there are many parts of the world where the health care system may not be as strong as we would like to see it. It is going to be really important to build the capacity of these systems to both monitor the impact of climate change on health, but also to react in a timely way to the impacts of climate change on health.

So far politics and stakeholders worldwide have not paid much attention to health issues related to the use of fossil fuels and the climate crisis. Do you see any evidence that this will change now or in the near future?

Certainly, health is more prominent than it was. At the same time it is still not as prominent as we would like to see it. Health is still seen as somewhat peripheral to the main issues of climate change and I think that is a profound mistake. However, we have seen some developments in recent years and we have seen a much more assertive group of health professionals and health organizations. You may remember that for COP26, there was a letter signed by representatives of over 40 million health professionals from around the world calling for climate action. That would not have happened a few years ago. Now we are seeing health professionals becoming much more active in their own communities, communicating to the public about the health effects of climate change and the need for urgent action. Hopefully, the central importance of safeguarding human health through climate change policies will increasingly be recognised over the coming years. That is what we will be pushing for very hard.

What about the health care system itself and its carbon footprint?

We know that the health care sector itself is an important source of greenhouse gas emissions. It is about 5 percent of emissions overall. In some countries, like the USA, it is actually much more than that. So the health care professions also need to get their own house in order. At the last UN Climate Summit in Glasgow 52 governments committed themselves to creating more resilient low-carbon healthcare systems. Fourteen of them gave a date when they aim to phase out carbon emissions from the healthcare system – by 2050 or earlier. So there is a lot of work going on in actually decarbonising the healthcare system. Which means not just decarbonising the energy supply, but also the supply chains. Because a lot of that carbon is embedded in pharmaceuticals, medical equipment, and so on. Obviously, these industries are very carbon intensive. Some anaesthetic agents, such as desflurane, are highly climate active, as are propellants in some asthma inhalers. So there is a great deal that the health professionals can do both within their own healthcare sector, but also through other sectors as well.

Do we still have time to tackle climate change?

Well, sadly we have lost a lot of time. We are already at 1.2°C global average temperature increase. If we had acted a few decades ago, we would not be where we are now. But we do have time to reduce some of the most extreme impacts of climate change on health and human society more generally. So if we act quickly, we can still keep the global average temperature to under 2°C and that would be very important for the health and flourishing of humanity in years, decades and centuries to come.

Interviewer: Henner Weithöner, Journalist, Berlin/Germany