There's a growing problem across the world, one that could make keeping livestock outdoors almost impossible in just a few decades, and jeopardize the health and livelihoods of hundreds of millions of people.
That problem is heat stress, caused by rising temperatures and global warming. It's a serious problem which is already affecting livestock health and welfare, particularly in outdoor farming, and subtropical or tropical zones. In the last episode of this season, presenters Brenda Coromina and Elliot Carleton hear from Philip Thornton, ILRI scientist and one of the top 50 most influential climate scientists worldwide. He warns about the consequences of living in a world where two-thirds of all cattle could be at risk of heat stress, along with many other livestock species.
What options are there for mitigation and adaptation? And whose responsibility will it be to avert disaster? Listen to The Boma to find out!
Elliot: Welcome back to the Boma. A podcast from the International Livestock Research Institute where we discuss how sustainable livestock is building better lives in the Global South.
My name is Elliot Carleton.
Brenda: And I’m Brenda Coromina.
Elliot: Today, we’re going to talk about a growing problem in the developing world, one that could threaten the viability of outdoor livestock production, and in doing so, jeopardize the health and livelihoods of hundreds of millions of people—that problem is heat stress.
Brenda: But before we go any further, what exactly is heat stress?
Philip: So I mean as in people heat stress in livestock, sort of arises because of a combination of various factors--high air temperatures, high relative humidity and solar radiation and wind speed. And all these things affect an animal's ability to thermoregulate or to keep its temperature within sort of acceptable bounds.
Brenda: That was Phillip Thornton, one of the top 50 most influential climate scientists in the world, according to Reuters. As a principal scientist at ILRI, his research focuses on assessing, prioritizing and targeting climate change adaptation options to support smallholder farmers.
Philip: In the very early 2000s, we started looking at some of the climate change impacts on, we actually started on sort of crop production, but over the years I've been involved in I guess quite a lot of work around, sort of how, what the impacts may mean for small scale farmers, particularly in low and middle income countries.
And climate change. I mean, I guess the science has been around for long enough that it was sort of fairly clear that agriculture in general crops, livestock and things were going to get sort of increasingly bad, particularly for small scale farmers.
And so it just seemed like as we've gone through time and the impacts have become more and more sort of worrying, I would say. And of course the effects on small scale farmers become more pronounced in many places, and so it seemed to me an important area for research that we should try to get a grip on.
Elliot: But while there has been a fair bit of research on crop impacts, not too many people have looked into how rising temperatures and heat stress could affect livestock, especially in the developing world.
Philip: And so this seems, you know, just a massive imbalance. It really needs to be corrected. Given that almost everywhere you go in say sub Saharan Africa or South Asia there are always livestock around and they are sort of a critically important component of farm systems and for the livelihoods and so on. And so this seems an imbalance that we really need to look at.
Brenda: Recent research into heat stress and livestock has started to address this imbalance.
Philip: At the moment there's something like 1.4 billion cattle on the planet. And sort of, currently there's probably it's about maybe 6 or 7% of all those animals are affected to some extent by heat stress, and most of those are in the lower latitudes, and so by the time you get to the end of the century and under a high greenhouse gas emission scenario then that 6 or 7% will increase to something like 65% or even 70%.
Brenda: That high greenhouse gas emission scenario means a situation in which atmospheric CO2 concentrations climb to around 630 parts per million by 2060 and to around 1020 parts per million by 2100. And we’re already well on our way there—for reference, in 2020 atmospheric CO2 concentrations were around 412 parts per million.
Elliot: If that happens, we would be living in a world where around 2/3 of all cattle globally would be at risk of heat stress. And that’s just cattle—other livestock species would be affected as well. This would potentially make outdoor livestock production impossible in many parts of sub Saharan Africa and the rest of the developing world because the impacts of heat stress on livestock can be extremely severe.
Philip: With heat stress that’s going above what animals can tolerate, then there are all kinds of impacts in terms of, the feed intake gets reduced, and which can obviously have knock on effects on productivity of milk or meat and of course they can, it can seriously affect animal welfare, and so it's obviously animals trying to stay within their sort of comfort zone as it were. If that's not possible, then obviously their welfare can be severely affected. If there are sort of large amounts or long periods of extreme heat stress, then it may reduce animals’ fertility and it can increase their susceptibility to disease and in extreme cases it can kill animals.
Brenda: The effects on animal welfare and health are obviously very concerning. But they are just the tip of the iceberg because when livestock are affected, so are people.
Elliot: Right. There’s the growing demand for animal-source foods in the developing world. And as Dr. Lora Iannotti told us in a previous episode, animal-source foods are also crucial to fighting global malnutrition. If heat stress reduces the productivity of livestock, and in some instances kills them, it would be devastating for the health and nutrition of millions of people across the developing world.
Brenda: And we can’t forget the millions of livelihoods connected to livestock that could also be destroyed.
Elliot: Given all these challenges associated with heat stress, it’s definitely an issue that deserves immediate global attention.
Brenda: But as we have seen, so far the world hasn’t taken the necessary steps to meaningfully address the climate crisis. And considering that so many people in the developing world depend on livestock for livelihoods and nutrition, what kind of world would we be looking at if heat stress made it so that outdoor livestock production was no longer viable?
Philip: Yeah, well, I mean I think some of the impacts could be, you know could be really serious because it's, as you know, livestock play all these, a whole range of roles in small scale farming systems. And I mean they’re sources of assets, and they're often for poor, vulnerable people. They offer some of the only assets they really have that can be converted in times of great stress. They can, you know, livestock can be sold if they need income and for school fees or things such as, things like that. And there would be substantial losses of income at the household level, like particularly for, say, dairy producers.
Generally it would sort of just decrease the resilience of the household and family if livestock were not were not able to be kept, then they’re are just sort of fewer options for the household to be able to cope in times of adversity. And you've mentioned another key one already in the nutrition and so decreased dietary diversity, which again could very well be an outcome of or an impact of increased heat stress on livestock.
And so, the loss of say livestock or animal-based foods could be a crippling blow for many millions of households in the tropics and subtropics that depend on them.
Elliot: And the impact of heat stress on livestock would be devastating not only at the household level but also for national economies.
Philip: Yes exactly. Or this would, alternatively you could see it as putting big pressure on governments to import animal source foods. Which is, then, it's yet another use of precious foreign exchange. And so I mean, I think you could see it as sort of, it would be operating in at least two ways. So yeah, increased prices for consumers, which would make it sort of much more challenging for consumers to access animal source foods, as well as, or increased imports from other places, which would then also have knock on effects on the sort of the national economy,
Elliot: All this is making me wonder to what extent mitigating some of these future challenges is even still a possibility.
Brenda: Me too. Can we actually prevent these predictions from becoming reality, or is the warming used in these projections pretty much already locked in?
Philip: No, I think mitigation is hugely important because we could, you could change the situation from being sort of by mid-century from being sort of that serious to becoming sort of much less serious by the end of the century. And so as you might expect, though, the costs of adaptation and the costs to small scale farmers' livelihoods will increase massively the longer we go on doing nothing about this issue like in so many issues.
Brenda: Well that is certainly encouraging that we can still stop some of those projections from becoming reality—if we are able to make the necessary reductions in our greenhouse gas emissions to avoid those high emission scenarios.
Elliot: And along with mitigation, I would guess that adaptation is also important to help manage heat stress impacts when they do arise in livestock.
Brenda: Yeah I think that’s definitely true—but adaptation measures can be difficult to implement because those most susceptible to heat stress are poor, vulnerable farmers in the developing world. So in addition to being effective, adaptation measures must also be affordable and available to smallholder farmers.
Philip: There's a range of relatively low cost options that may be suitable in different places. In parts of Latin America they've done quite a lot of work in silvopastoral systems, so this is, these are grazing systems with trees in them, and there are some interesting papers that show that if you put trees in particular arrangements to provide shade for animals then that could have a substantial impact in terms of reducing heat stress that’s suffered by cattle. So there's, you know, there are options there. There are other relatively low cost options such as providing shade through say with sheds or providing sheds with just manually operated fans. And in parts of India they already bathe their animals in water a couple of times a day. These are all options that could be considered.
I mean, another thing that I think we mentioned in the papers is also just moving animals to say to areas of perhaps higher altitude where humidity is sort of decreased compared with other areas. I mean, of course it's not always so easy just to move animals from one place to another, but there are places I think where this could be a feasible option.
Brenda: And another potential adaptation strategy, which ILRI is looking into, takes advantage of the fact that certain livestock breeds and species are less susceptible to heat stress than others.
Philip: Sheep and goats, and goats in particular, tend to be more resilient than cattle. So on the species basis, and pigs and poultry may also be less resilient. And so I mean one of just sort of, by the by, one of the adaptations that can be open to the small scale farmers would be to shift from say some of the species that are more susceptible to species that are less susceptible. So in that case it would, it could be moving from say cattle to some of the small ruminants such as sheep and goats. Within particular species, then there are, there can be quite large breed differences, and so some breeds are more tolerant of relatively high levels of heat stress than others.
Also, there's been some work done on goats as well. And so again, from an adaptation perspective, there may be prospects for crossbreeding and say, local animals that are, have a higher heat tolerance than others. And so there are some prospects there.
Elliot: OK, so there are clearly both mitigation and adaptation strategies available to us. But, is there anything else we should be doing to prevent some of those looming dangers we’ve discussed?
Philip: Ok yeah, I mean this is a good question. I think the important thing is I think just not to lose hope.
Looking at it sort of like glass half full rather than glass half empty, and I get the feeling, and I think many other people do as well, that over the last two or three years, and I'm not sure quite whether if we're at that sort of that societal tipping point yet. But I think we may be getting close to it where, and I'm particularly thinking of younger people because I think they're the ones who are going to have to deal with many of these issues in the future because the old people like me will be sort of like we'll be out of it completely. So I think we may be close to a tipping point where there's enough movement from the ground upwards onto governments to really make them face these issues.
Elliot: You know, Brenda, I’m really struck by Philip’s comment that it's people like you and me and others in our generation that are going to have to address these issues. It can be challenging to remain hopeful about the future of our planet, but what I take from Philip is that there are still things we can do to mitigate and adapt to climate impacts and prevent them from reaching their most dangerous potential.
Brenda: Definitely. It can be difficult to talk about the dire projections related to climate change—but we can use discussions with people like Philip to gather the information and develop the tools necessary to face those challenges head on.
Elliot: And I think that’s a great place to leave off for today! Thank you so much to Dr. Philip Thornton for taking the time to not only discuss the problems associated with heat stress and livestock, but also for showing us what we can all do to address them.
Brenda: And thank you to our listeners for joining us. If you enjoyed today’s episode, we hope that you will leave us a review, and please don’t forget to subscribe!
Elliot: We’ll catch you next time on The Boma. I’m Elliot Carleton.
Brenda: And I’m Brenda Coromina.