With early weather reports predicting further hot weather in August, the FBU warns that the fire and rescue service across England is unlikely to be able to cope with wildfires like those seen during the historic hot spell in July.
The latest available Home Office figures show there were the equivalent of 591 full-time firefighters at the North Yorkshire Fire and Rescue Service as of the end of March last year – 298 wholetime and 294 on-call.
However, this was down from 601 a year before and 692 in 2011 – a fall of 15% over a decade.
Using the latest fire service area population estimates for 2020, it means the rate of firefighters per capita in North Yorkshire has fallen from around 8.7 per 10,000 people to 7.1 over this period.
The FBU said the Government and chief fire officers have "decimated" the service nationally, with almost 10,000 fewer firefighters across England last year than a decade previously.
Riccardo la Torre, FBU national officer, said: "That is outrageous complacency in the face of rapidly rising temperatures.
"Fire and rescue services should plan and prepare for foreseeable risk, yet it is clear they are not doing that."
He said the wildfires caused by record temperatures in mid-July should have been a "wake-up call" for the Government, but there have been no major funding announcements.
And long-range weather forecasters WX Charts are predicting another heatwave in August, with temperatures across much of England estimated to reach 30C.
Mr la Torre added: “Put simply, further heatwaves will result in more wildfires, and the fire and rescue service is unlikely to be able to cope.
“Firefighters face a climate emergency at work and a cost-of-living crisis at home."
He said the recent 2% pay offer – which the FBU says equates to a real terms pay cut of around 7% over the last year – is evidence of the Government treating firefighters in a "disgusting manner".
Greenpeace said there has been an alarmingly consistent increase in wildfires in the UK over recent years, and without government action this will only worsen.
Rebecca Newsom, head of politics at the environmental campaign group, said: "For decades, successive UK governments have fanned the flames of climate change, and the wildfires that come with it, by failing to cut emissions and reduce our dependence on fossil fuels fast enough.
"For the next Prime Minister, this, alongside tackling the cost-of-living crisis, must be their number one priority."
The Home Office figures show that 2,431 men and women joined the national fire service in 2020-21 – down from 2,845 in the previous financial year.
In North Yorkshire, the number of joiners dropped from 64 to 12 over this time.
A Home Office spokeswoman said: “The Government is committed to ensuring fire services have the resources they need to keep us safe, including from wildfires, and overall fire and rescue authorities will receive around £2.5 billion in 2022-23."