Could the climate crisis be worsening bird flu outbreaks?

Experts are considering whether rising temperatures could lead to more infections, writes Zoe Tidman

Defra officials dispose of culled ducks at a farm near Nafferton, East Yorkshire, where a strain of bird flu has been confirmed (Getty)

As if the Covid pandemic weren’t enough, Britain is also dealing with its largest-ever outbreak of bird flu – including a “very rare” case detected in a human.

Avian influenza has been detected at more than 60 premises over the past few months, according to the Department for Environment, Food and Rural Affairs (Defra).

It has been just a year since Britain saw its previous largest outbreak involving 26 cases between late 2020 and early 2021.

Christine Middlemiss, the UK’s chief veterinary officer (CVO), said last month there would usually be a “reasonably-sized outbreak” followed by two or three quiet years. “But that’s not happening.”

Outbreaks instead appear to be growing in size, and scientists are wondering if the climate crisis could be playing a role.

Asked if global warming had anything to do with increased infections, she said it was “certainly one of the thoughts that our experts are having.”

“The birds migrate to the north of Russia over the summer and mix with other birds on other global flight pathways and exchange the viruses. So it’s quite plausible that with climate change and change in pathways that different mixing is going on,” she told BBC Radio 4’s Today programme.

Professor Mick Bailey from the University of Bristol’s Veterinary School says wild fowl migration is driven by temperature, and it is expected that rising temperatures will change their migration patterns, including where they go and when.

While different behaviours will change how bird flu spreads, it is not yet known exactly how this could impact UK outbreaks, Bailey said, and we are a “long way” from finding this out.

The climate crisis could force birds to mix together more closely on their migration paths from the sub-Arctic in autumn before reaching the UK, which could lead to increased spread.

These birds choose their environments based on optimal temperatures and resources, Bailey said. As the climate crisis affects the distribution of resources, birds may be forced to look for food in different areas.

“Potentially that’s going to result in a much greater density of birds in a more limited number of areas and change the way they transmit bird flu to domestic poultry,” he says.

Professor Mark Fellowes, an ecology professor at the University of Reading, told The Independent: “There’s little doubt that climate change is altering both the timing and patterns of bird migration.”

He said: “As migration becomes disrupted, the risk may increase of wild bird populations mixing and disease spreading, but how these dynamics will play out is not clear.”

A more traditional explanation is likely for the “crossover” case of avian flu, which came after a flock of ducks was confirmed to be infected, prompting a culling on New Years Day.

Alan Gosling, from Buckfastleigh, Devon, tested positive for the infection after keeping the ducks in his house.

He explained he had always cared for wild birds and rescued many from his local area, and was unaware he had the virus until he was advised to take a test.