January 8, 2025

expert reaction to LA wildfires

Scientists comment on Los Angeles wildfires.

Dr Maria Lucia Ferreira Barbosa, wildfire scientist, UK Centre for Ecology & Hydrology (UKCEH), said:

“The fires in Los Angeles are a stark reminder of how extreme weather increases fire risk.  It is likely that heavy rains from El Niño last year fuelled vegetation growth, which has since dried out during the recent prolonged dry spell and, along with strong winds, creating perfect conditions for wildfires to spread.

“Unfortunately, the proximity of these fires to urban areas significantly increases the risk to people and property.

“While it is too early to link the current Los Angeles fires to climate change, our research has shown that global warming brings more prolonged dry conditions that exacerbate the spread of wildfires.

“There is projected¹ to be a global increase of extreme fires of up to 14 per cent by 2030, 30 per cent by 2050 and 50 per cent by the end of the century.”

1 https://www.unep.org/resources/report/spreading-wildfire-rising-threat-extraordinary-landscape-fires

Prof Stefan Doerr, Editor-in-Chief of the International Journal of Wildland Fire; and Director of the Centre for Wildfire Research, Swansea University, said:

“Key factors for wildfires are low relative humidity, strong wind and drought.  ‘Fire weather’ refers to the weather conditions that are conducive to wildland fire.  It does not necessarily need to be very warm – however, warm temperatures lead to lower relative humidity.  The low humidity combined with the strong winds ’suck’ further moisture out of the already dry vegetation and increase its flammability.  Once ignited, the strong winds fan the flames.  The situation is made worse by the topography (fires burn more intensely and move more rapidly in steep terrain) and the fact that this area of California is dominated by naturally very fire-prone (i.e. very flammable) shrub vegetation.

“It looks like today is likely to continue with extreme fire behaviour (rapid movement of fire aided by flying embers) given the strong winds and low humidity.

“We know from previous evidence that climate change has already made fire weather more severe and the fire season longer in most regions of the world.  While fires are common and natural in this region, California has seen some of the most significant increases in the length and extremity of the fire weather season globally in recent decades, driven by climate change.

“That said, it is too early to say to what degree climate change has made these specific fires more extreme.  This will need to be evaluated in a more detailed attribution analysis.”

Prof Rory Hadden, Professor of Fire Science, University of Edinburgh, said:

Do we know why this has happened?

“The initial cause of the fire is probably not worth speculating at this time.  The rapid growth is somewhat unusual (but sadly we are seeing it more regularly).  It has been reported that this is due to the dry (low humidity) Santa Ana winds.  The rapid fire growth makes it hard to reach the fires and manage them when they are small, the landscape here – very hilly – is also challenging for fire fighting.

“The fire hazard here in addition to the flames is firebrands.  These are small (or sometimes not so small) burning embers that are blown buy the wind and can land in neighbourhoods and cause ignition of structures.  Many of these are produced from the burning of natural fuels but even more are generated once houses start burning.  This means that the fire spreads from house to house in neighbourhood very fast.  This quickly overwhelms fire fighters.

“Smoke and firebrands can also make escape challenging as visibility is reduced.  There are also evacuation problems as I understand due to limited access (note that this is typical of the areas susceptible to this kind of fire).

“One of the key reasons here is that it is desirable to build in these locations (on the edge of a city, near nature) but this is inherently a higher danger area to live.  Landscapes need to be managed to keep up with evolving fire danger driven by climate change.  This is a huge challenge for governments as there are many political issues associated with management of wild spaces (as well as costs).  California actually already has some great guidance on this but it is difficult to enforce and indeed enact sometimes.

How unusual are these fires in this location and at this time of year?

“Sadly not that unusual and not that unexpected.  Several weather watchers had been reporting high fire danger forecasts.  We are in general good at knowing the drivers of fire danger but it is a huge societal problem of how to prepare and react.”

Dr Kimberley Simpson, Fellow in nature-based climate solutions, University of Sheffield’s School of Biosciences, said:

“A prolonged period of unusually low rainfall, coupled with the arid Santa Ana winds blowing in from inland areas, has created the perfect conditions for disaster: bone-dry vegetation that ignites easily in the parched, low-humidity environment, fueling rapidly spreading wildfires.

“These devastating fires are not only occurring with greater intensity but are also striking earlier than Southern California’s typical fire season, highlighting how climate change is reshaping fire regimes – the characteristic patterns of wildfire in a region.

“While working to slow the effects of climate change and reduce fire risk through strategic vegetation management, we must also adapt to the new ‘normal’ of larger, more intense fire regimes and enhance our preparedness for these escalating challenges.”

Brent Walker, Met Office Expert Meteorologist, said:

“The development of the Santa Ana winds has probably aided the development of the wildfires in the Los Angeles area.  These are not uncommon in winter and tend to develop, in varying degrees of magnitude, when pressure rises strongly, following the passage of weather system across the region.  Santa Ana winds can be very strong, reaching 60-70 mph at times.  The Santa Ana winds also generate very low humidity, with observations in the areas showing between 15 and 20%.  Both strong winds and low humidity aid the spread of wildfires, although don’t necessarily generate them in the first instance.  Winds should begin to ease tomorrow.”

Declared interests

Dr Maria Lucia Ferreira Barbosa: “No interests to declare.”

Prof Stefan Doerr: “I declare no conflict of interest.”

Prof Rory Hadden: “Funding:

National Institute of Standards and Technology;

USDA Forest Service;

Strategic Environmental Research and Development Programme (US Department of Defense);

Scottish Government;

UKRI/EPSRC;

Dstl;

Building Safety Regulator.”

Brent Walker: “Nothing to declare.”

For all other experts, no reply to our request for DOIs was received.