Have you enjoyed this pandemic? Because climate change could soon bring us the next one

One of the warning signs of a false conspiracy theory is that it has an answer for everything. Any evidence against is just proof that the conspiracy is bigger than they thought. This is not a universal rule, of course, but it’s well-known enough that I’ve seen it cited to accuse both the theory of evolution and the theory of anthropogenic global warming of being conspiracy theories.

Certainly, there have been conspiracies associated with climate change – deliberate efforts to mislead the public, and to prevent real action – but the problem here is a category error. People who make this argument are applying a general rule about theories explaining human activities to scientific theories explaining observed phenomena, backed up by reproducible research. That said, I really sympathize with those who have that reaction to climate change. What we’ve done to our planet is happening at a scale far beyond our normal frame of reference, and it’s affecting every part of the surface of this planet. That means that no matter what happens, it really is reasonable to ask, “how did climate change influence this?”

That goes for political and cultural shifts, volcanoes, and yes – pandemics:

As the Earth’s climate continues to warm, researchers predict wild animals will be forced to relocate their habitats — likely to regions with large human populations — dramatically increasing the risk of a viral jump to humans that could lead to the next pandemic.

This link between climate change and viral transmission is described by an international research team led by scientists at Georgetown University and is published April 28 in Nature(“Climate Change Increases Cross-species Viral Transmission Risk,” doi:10.1038/s41586-022-04788-w).

In their study, the scientists conducted the first comprehensive assessment of how climate change will restructure the global mammalian virome. The work focuses on geographic range shifts — the journeys that species will undertake as they follow their habitats into new areas. As they encounter other mammals for the first time, the study projects they will share thousands of viruses.

The scientists say these shifts bring greater opportunities for viruses like Ebola or coronaviruses to emerge in new areas, making them harder to track, and into new types of animals, making it easier for viruses to jump across a “stepping stone” species into humans.

“The closest analogy is actually the risks we see in the wildlife trade,” says the study’s lead author Colin Carlson, PhD, an assistant research professor at the Center for Global Health Science and Security at Georgetown University Medical Center. “We worry about markets because bringing unhealthy animals together in unnatural combinations creates opportunities for this stepwise process of emergence — like how SARS jumped from bats to civets, then civets to people. But markets aren’t special anymore; in a changing climate, that kind of process will be the reality in nature just about everywhere.”

You may remember some of the more charming representatives of the U.S. population making racist jokes about the habits of Chinese people, following reports about the origin of the virus. It sort of seems like the “lab leak” theory has gotten more popular of late, but the racism hasn’t gone anywhere. The lesson we should take from the COVID-19 pandemic is similar to the lessons of this research. Humans going into new habitat in search of resources brings us in contact with new diseases, some of which might infect us. Likewise, the rising temperature will force animals out of their historic homes, making new diseases more likely to bring themselves to us.

Of concern is that animal habitats will move disproportionately in the same places as human settlements, creating new hotspots of spillover risk. Much of this process may already be underway in today’s 1.2 degrees warmer world, and efforts to reduce greenhouse gas emissions may not stop these events from unfolding.

An additional important finding is the impact rising temperatures will have on bats, which account for the majority of novel viral-sharing. Their ability to fly will allow them to travel long distances and share the most viruses. Because of their central role in viral emergence, the greatest impacts are projected in southeast Asia, a global hotspot of bat diversity.

“At every step,” said Carlson, “our simulations have taken us by surprise. We’ve spent years double-checking those results, with different data and different assumptions, but the models always lead us to these conclusions. It’s a really stunning example of just how well we can, actually, predict the future if we try.”

As viruses start to jump between host species at unprecedented rates, the authors say that the impacts on conservation and human health could be stunning.

“This mechanism adds yet another layer to how climate change will threaten human and animal health,” says the study’s co-lead author, Gregory Albery, PhD, a postdoctoral fellow in the Department of Biology in the Georgetown University College of Arts and Sciences.

“It’s unclear exactly how these new viruses might affect the species involved, but it’s likely that many of them will translate to new conservation risks and fuel the emergence of novel outbreaks in humans.”

Altogether, the study suggests that climate change will become the biggest upstream risk factor for disease emergence — exceeding higher-profile issues like deforestation, wildlife trade and industrial agriculture. The authors say the solution is to pair wildlife disease surveillance with real-time studies of environmental change.

“When a Brazilian free-tailed bat makes it all the way to Appalachia, we should be invested in knowing what viruses are tagging along,” says Carlson. “Trying to spot these host jumps in real-time is the only way we’ll be able to prevent this process from leading to more spillovers and more pandemics.”

“We’re closer to predicting and preventing the next pandemic than ever,” says Carlson. “This is a big step towards prediction — now we have to start working on the harder half of the problem.”

“The COVID-19 pandemic, and the previous spread of SARS, Ebola, and Zika, show how a virus jumping from animals to humans can have massive effects. To predict their jump to humans, we need to know about their spread among other animals,” said Sam Scheiner, a program director with the U.S. National Science Foundation (NSF), which funded the research. “This research shows how animal movements and interactions due to a warming climate might increase the number of viruses jumping between species.”

That last paragraph is interesting to me. For one thing, it’s an entirely understandable bid to get folks outside the scientific community to pay attention. Sensationalism seems to be all that works these days, and that works well when the material in question is sensational by nature.

For another thing, I think that the focus on the direct threat to humans hides at least a couple threats that are less obvious. The one that concerns me is the risk of diseases spreading not just to humans, but to the species we rely on for food.

That’s right! This was a secret agriculture post! I tricked you, and now you’re invested in hearing the final point!

Which is that while pandemics affecting us are scary and dangerous, we should also be very worried about pandemics affecting our crops. We depend on a terrifyingly small number of species for most of our food, and they’re no less vulnerable to disease than we are. I’m not sure how much we can do about this aspect of the problem, beyond “deal with climate change”, but I can think of a couple things.

First, obviously, I still want to move food production indoors. That doesn’t guarantee crop safety, but it certainly helps limit what the crops are exposed to. Second, as we invest in the infrastructure and power sources we need, we should also invest in diversifying our food sources. I guess this could be based on local taste and decisions, but I think that governing bodies ought to actually spend money on it, as a partial defense against pathogen-related crop failures.

The scientists who warned about the dangers of a pandemic were largely ignored, and hundreds of thousands of people died because of it. That number is dwarfed by those killed by ignoring climate scientists, but in both cases, the fact that we knew better (as a species) – the fact that we could have heeded warnings and done better – means that we still can. We can do better, and the path we’re on isn’t one we’re required to follow to destruction.

We can set a new course.

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  1. johnfarnham says

    “Bigots, doomers, and trolls will have their comments edited or deleted. ”
    Guess I should do my best to be considered one of those. BTW I consider YOU a ‘doomer’. It isn’t that I do not ‘believe’ in ‘climate change’. Rather I recognize no reason why it should not – unpredictably, but likely conforming to past patterns of experience in large part. It is fun to hear you refer to disbelief in anthropogenic global warming / climate change as a matter for a ‘conspiracy theory’ – although when government levies a tax it is no secret what their theft is about. Nor is it especially credible that man should be responsible for change decades hence. Such a projection is still the speculation it ever was. Not even the I.P.C.C. calls its computer emulation of the function of crystal balls factual – though if one is silly enough it can be called credible. There is no data – nor can there be. Things which have not happened remain unmeasurable..

  2. says

    But a lot of things have happened before. For example, we know what happens to water when you dissolve CO2 in it: It gets more acidic. This is a demonstrable phenomenon that is even occurring within your own blood at this very moment.

    We also know what happens to organisms when the pH shifts too far; talk to people who keep fish tanks and they’ll tell you. And we know that if one species disappears, it affects the entire food chain and health of the ecosystem. This is observable on local scale by looking at streams and lakes.

    While there are also non-human effects going on, that doesn’t mean we can ignore the effects of our own behavior, especially since we can draw a direct causal line from our behavior to a change in ecology. It’s not a question whether we’re affecting the world; the question is how much and what we can do to mitigate it.

  3. says

    @Johnfarnham – I tend to allow a little leeway for discussion, disagreement, and so on. My problem comes when we enter the realm of advocacy, or when we start going in circles. The “doomers” in question are those who think our extinction due to climate change is inevitable and near, and therefor we shouldn’t bother doing anything about it. It’s the flip side of those who say the problem isn’t happening, so we shouldn’t do anything about it.

    As to your claim that it’s “not especially credible”, I’m afraid the only two reasons why you say that are dishonesty or ignorance. I’ll assume – for now – that it’s ignorance, and we’ll see where that goes. To begin with, you seem to think that the field of climate science is a relatively new one.

    It’s not.

    We’ve known how CO2 interacts with heat in our atmosphere since 1856. As in – Eunice Foote was able to measure it then. Her work has since been confirmed countless times by countless people, and a version of it is still used as a basic science fair project to this day.

    The first prediction that CO2 from the burning of fossil fuels would raise this planet’s temperature was in 1896, by Swedish chemist and physicist Svante Arrhenius. This wasn’t just a guess. He and many others had found evidence of past ice ages, and were studying what could cause such a thing to happen, when another scientist approached him with his evidence that carbon dioxide from burning coal was actually accumulating in the atmosphere. The prediction was made not based on random guesswork, but based on the measurable physical properties of carbon dioxide, and the measurable rate of increase in the atmosphere.

    That was 126 years ago, also known as 12.6 decades.

    When Arrhenius made the prediction, he calculated it would take around 3,000 years for the climate to warm enough for palm trees to grow in Sweden, and he was pretty happy about the idea. That was based on fossil fuel consumption in the 1890s, you understand. The rate of consumption has gone up a bit since then.

    Already you can see that this isn’t a prediction NOW about something happening in the future, so much as a prediction from the past that we’ve checked over and over and over for over a century, and that has turned out to be accurate, no matter how many times we run the numbers.

    This is what science is. It’s a method for taking information we know, and using it to make predictions, which are then tested.

    The field of climate science continued after Arrhenius’ work, of course. The term “climate change” goes back to the 1930s, if memory serves, but it was in the late 1950s when things really kicked off. That’s when Charles Keeling started making some noise about what his CO2 measurements at Mauna Loa observatory were showing. This graph is known as “Keeling Curve“:

    1958 is also when the first televised warning about climate change appeared on Bell Telephone Science Hour

    I want to emphasize, again, that all of this was literal decades before that warming was measurable. This is not something scientists came up with after the fact to explain warming that was being seen, it’s something scientists successfully predicted decades before it happened. In the case of Arrhenius, he predicted it and then died of old age decades before it happened. It was also – in case I need to tell you this – decades before computer models or the IPCC existed.

    The creation of the IPCC was the moment when governments realized that they should at least look like they were doing something about this problem. That’s what the “I” of that acronym is – “Intergovernmental”.

    That came almost a century after the first prediction of global warming caused by human activities, and it came because the evidence had already been overwhelming for years

    This is no different from Eratosthenes measuring the circumference of the earth in 276 B.C.E., literally thousands of years before we were able to actually circumnavigate it whenever we wanted, or even go into space and take a look from the outside. This is no different from our ability to predict that a dramatic increase in the number of new smokers THIS year, will lead to a measurable increase in cases of lung cancer a few decades down the line.

    Every aspect of your life involves technology that came from predictions made decades or centuries before those predictions were realized. This is not the divine revelation of prophecy, it’s just a basic understanding of the material realities of our world.

  4. StevoR says

    I love the ending of this. Those last few sentences you wrote here. Let’s set a new course.

    Yes. Make it so people!

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