Portugal's drought reduces the fire season, not increases it

We’re getting our annual series of reports on the fire season in Portugal, Spain, Greece and so on. This is mixed in with reports of high temperatures and drought. We just thought it might be worthwhile emphasising what such reports don’t - drought reduces the fire season, high temperatures make no difference.

Wildfires in Portugal have left 29 people injured as thousands of firefighters and dozens of aircraft battle the blazes. Authorities said 12 firefighters and 17 civilians required medical treatment for minor injuries, as reported by the Portuguese state broadcaster RTP and local media. By Sunday afternoon, Portugal’s civil protection agency said more than 3,000 firefighters were tackling active blazes. The country is enduring a heatwave that is due to worsen, with temperatures expected to reach up to 43C (109F) on Tuesday. On Sunday, the EU activated its firefighting air fleet assistance programme, which allows member states to share resources to help Portugal.

Thousands of firefighters, yes, the Bombeiros here is a voluntary organisation mostly paid for by charity collections at roundabouts, supermarkets and the like. It’s also something that large numbers of adults join precisely so as to provide cover for the fire season*. For it is a fire season that comes around every year, starting right about now. There has in fact been a substantial reduction in the number of fires in recent decades. But that’s because the automatic granting of building and development permission in forests burnt down has stopped. Perish the thought but perhaps some of them used to be started in order to gain the development permission.

It’s also worthwhile understanding what drives the fire season. High temperatures don’t - scrub and forest is not notably more flammable at 43 oC than at 39 oC, so those peak temperatures of a heatwave over more normal temperatures make little difference. Wind, of course, makes a difference to the speed of spread.

The art of firefighting here is that if it’s out in the country then monitor but let it burn - it is that natural part of the ecological cycle here after all. Isolated houses and cottages will be allowed to go up with it too. It’s only when the flames threaten substantial settlement that actual fighting of it occurs.

Drought though reduces the size and intensity of any fire. For the cycle here is of rain in the winter and plant growth during that winter and early spring. By now - this mid-July - there’s been no rain for months as an entirely usual part of the cycle, the plant life is dried out and largely already seeded and dead. This produces the tinder the fires feed upon.

What produces more tinder and thus a stronger fire season is a wetter winter - the increased rainfall leading to greater growth which is by this time of the year ready to burn.

Portugal is indeed going through a drought, the reservoirs are low. But it is exactly this which leads to a lesser fire season - there’s less of that winter growth now dry and ready to burn.

It’s possible - we take no view on this - that the drought is caused by climate change. It’s equally possible that the high temperatures are also so caused, again no view taken. But the fire season is normal, the drought reduces the intensity of the fires and so, if it is indeed all caused by climate change then the net effect is a reduction in the damage done by forest fires, not an increase.

Which isn’t something that the more general press coverage of the issue tends to suggest now, is it?

*An estate agent once apologised for a delay in concluding a transaction, saying that he and his entire office had been out helping to deal with this. That’s what happens, community mobilisation - the supermarkets had systems whereby shoppers could purchase bottled water for the firefighters in the same way that food bank collections are made.