The highly destructive wildfires in Los Angeles US, in January 2025 are a warning to the World at large of the threat posed by climate change and its impact. Similar fires have been seen in the Mediterranean during their Summer period with similar devastating effects particularly in Greece.
The Copernicus Institute summarised the situation thus:
“2024 saw unprecedented global
temperatures, following on from the remarkable warmth of 2023. It also became
the first year with an average temperature clearly exceeding 1.5°C above the
pre-industrial level – a threshold set by the Paris Agreement to significantly
reduce the risks and impacts of climate change. Multiple global records were
broken, for greenhouse gas levels, and for both air temperature and sea surface
temperature, contributing to extreme events, including floods, heatwaves and
wildfires. These data highlight the accelerating impacts of human-caused
climate change”.
Key points -
2024 was the warmest
year in a multi-dataset record of global temperature going back to 1850.
2024 had a global
average temperature of 15.10°C; 0.12°C higher than the previous highest annual
value in 2023.
2024 was 0.72°C
warmer than the 1991–2020 average, and 1.60°C warmer than the
pre-industrial level, making it the first calendar year to exceed 1.5 above
that level.
The last ten years
have been the warmest ten years on record.
Each month from
January to June 2024 was warmer than the corresponding month in any previous
year. August 2024 equalled the record warmth of August 2023 and the remaining
months from July to December were each the second warmest for the time of year,
after the corresponding months in 2023.
On 22 July 2024, the
daily global average temperature reached a new record high of 17.16°C.
Powerful Santa Ana winds, near hurricane strength at times, swept down the mountains outside Los Angeles and pushed wildfires into several neighborhoods starting Jan. 7, 2025. Well over 1,000 homes and several schools had burned by Jan. 8, and at least five people had died. Officials urged more than 100,000 residents to evacuate at the height of the fires, but with the winds so strong, there was little firefighters could do to control the flames.
Jon Keeley, a research ecologist in California with the U.S. Geological Survey and adjunct professor at UCLA, explains what causes extreme winds like this in Southern California, and why they create such a dangerous fire risk.
What causes the Santa Ana winds?
The Santa Ana winds are dry, powerful winds that blow down the mountains toward the Southern California coast.
The region sees about 10 Santa Ana wind events a year on average, typically occurring from fall into January. When conditions are dry, as they are right now, these winds can become a severe fire hazard.
Santa Ana winds blow down the mountains toward the coast, drying and warming as they descend.USGS
The Santa Ana winds occur when there is high pressure to the east, in the Great Basin, and a low-pressure system off the coast. Air masses move from high pressure to low pressure, and the more extreme the difference in the pressure, the faster the winds blow.
Topography also plays a role.
As the winds rush downslope from the top of the San Gabriel Mountains, they become drier and hotter. That’s a function of the physics of air masses. By the time the winds get to the point where the Eaton Fire broke out in Altadena on Jan. 7, it’s not uncommon for them to have less than 5% relative humidity, meaning essentially no moisture at all.
Canyons also channel the winds. I used to live in the Altadena area, and we would get days during Santa Ana wind events when the wind wasn’t present at all where we lived, but, a few blocks away, the wind was extremely strong.
These strong, dry winds are often around 30 to 40 mph. But they can be stronger. The winds in early January 2025 were reported to have reached 60 to 70 mph.
Why was the fire risk so high this time?
Typically, Southern California has enough rain by now that the vegetation is moist and doesn’t readily burn. A study a few years ago showed that autumn moisture reduces the risk of Santa Ana wind-driven fires.
This year, however, Southern California has very dry conditions, with very little moisture over the past several months. With these extreme winds, we have the perfect storm for severe fires.
Dark smoke from the fires was evident from the Santa Monica, Calif., pier on Jan. 8, 2025.AP Photo/Richard Vogel
It’s very hard to extinguish a fire under these conditions. The firefighters in the area will tell you, if there’s a Santa Ana wind-driven fire, they will evacuate people ahead of the fire front and control the edges – but when the wind is blowing like this, there’s very little chance of stopping it until the wind subsides.
Other states have seen similar fires driven by strong downslope winds. During the Chimney Tops 2 Fire in Tennessee in November 2016, strong downslope winds spread the flames into homes in Gatlinburg, killing 14 people and burning more than 2,500 homes. Boulder County, Colorado, lost about 1,000 homes when powerful winds coming down the mountains there spread the Marshall Fire in December 2021.
Have the Santa Ana winds changed over time?
Santa Ana wind events aren’t new, but we’re seeing them more often this time of year.
My colleagues and I recently published a paper comparing 71 years of Santa Ana wind events, starting in 1948. We found about the same amount of overall Santa Ana wind activity, but the timing is shifting from fewer events in September and more in December and January. Due to well-documented trends in climate change, it is tempting to ascribe this to global warming, but as yet there is no substantial evidence of this.
More people now live in and at the edges of wildland areas, and the power grid has expanded with them. That creates more opportunities for fires to start. In extreme weather, power lines face a higher risk of falling or being hit by tree branches and sparking a fire. The area burnt because of fires related to power lines has greatly expanded; today it is the major ignition source for destructive fires in Southern California.
Firefighters work to extinguish burning homes in the Pacific Palisades neighborhood of Los Angeles on Jan. 8, 2025.AP Photo/Damian Dovarganes
The Eaton Fire, which has burned many homes, is at the upper perimeter of the San Gabriel Basin, at the base of the San Gabriel Mountains. Fifty years ago, fewer people lived there. Back then, some parts of the basin were surrounded by citrus orchards, and fires in the mountains would burn out in the orchards before reaching homes.
Today, there is no buffer between homes and the wildland. The point of ignition for the Eaton Fire appears to have been near or within one of those neighborhoods.
Homes are made of dried materials, and when the atmosphere is dry, they combust readily, allowing fires to spread quickly through neighborhoods and creating a great risk of destructive fires.
Parasite, zombie, leech – these words are often used to describe people in unkind ways. Many of us recoil when ticks, tapeworms, fleas, head lice or bed bugs are even mentioned. Coming across such unwelcome guests – in our hair, on our skin or in our beds – can be a real nightmare.
Parasites are often demonised and misunderstood. But the more we study these oddities and wonders of evolution, the more we appreciate their vital roles in ecosystems and our complex relationships with them. They’re essential to life on Earth.
As an ecologist with a focus on wildlife and conservation, I wrote this article to share some of my fascination for parasites and the importance of their extraordinary lives.
Cuckoos are known as brood parasites, tricking other birds into raising their own young.
What is a parasite?
Parasites rely on living organisms for food, to grow and to reproduce.
They can either live on the outside (ectoparasites) or inside (endoparasites) of their hosts. Far from being invited dinner guests, parasites typically turn up of their own accord and feed at the host’s expense, consuming part or all of them.
Parasites can live within their host (or hosts) for short or extended periods – in some cases many years – going largely unnoticed. For instance, one man lived with a tapeworm in his brain for more than four years until the headaches and strange smells become too much to bear. In other cases, parasites can kill their host.
In real life, examples include spider wasps that first immobilise their spider prey, lay an egg on them, and bury them. Then when the egg hatches, the wasp larvae devour the incapacitated spider. That is, of course, if another animal such as a “bin chicken (Sacred Ibis)” or insect doesn’t intervene.
Parasites are widespread and profoundly affect our world.
Parasites are typically much smaller than their hosts. Many are furnished with equipment for latching on and remaining attached, including hooks, suckers and “teeth”.
Endoparasites such as tapeworms are often flat, allowing them to live within the tight spaces inside other organisms. The flatworm Diplozoon paradoxum that lives in gills of some fish must conjoin with another to reach adulthood and reproduce. Once fused, they form a permanent, lifelong bond and mate with each other over many years.
One of the world’s most widespread parasites is Toxoplasma gondii. Some estimates suggest as many as one in three people are affected. This parasite’s main host is cats, large and small species. House cats are frequently infected, spreading this parasite through their faeces.
There are potential “benefits” too. Research suggests Toxoplasma infection, which can increase confidence and risk-taking, may even be linked with increased entrepreneurial and business-related activities. Indeed, this same study found that nations with higher rates of toxoplasmosis had a lower proportion of individuals concerned about failure related to new business ventures.
Toxoplasmosis is associated with a vast array of symptoms and medical conditions.
Toxoplasma gondii manipulates its host to increase transmission and continue its life cycle. Infected rodents may become unwitting participants in a game of cat-and-mouse-and-parasite in which they lose their fear of cats and instead become attracted to them.
Rather than manipulating host behaviour, as in the case of fungi that turn ants into zombies, some parasites cause body malformations. This makes hosts more likely to become prey for subsequent hosts and hence to continue the parasite’s life cycle. One of the most striking examples is a trematode (flatworms often known as flukes) that causes missing legs, extra legs or deformed legs in frogs and other amphibians. Extra legs, in some cases several, serve no function and simply impede movement, making it harder to escape predators.
Sometimes extra legs are a hindrance not helpful.Brett Goodman and Pieter Johnson
Parasites are fundamental to ecosystems and require conservation
Parasites are a big part of life on Earth. A study on the Californian coast found the sheer mass of parasites exceeded that of top predators. In particular, the biomass of trematodes was greater than that of birds, fish, burrowing shrimps and polychaetes (marine worms).
The presence of parasites (Gyrodactylus turnbulli) can affect how colourful male guppies are, influencing their ability to attract mates.Wikimedia commons, CC BY
Euan Ritchie, Professor in Wildlife Ecology and Conservation, School of Life & Environmental Sciences, Deakin University
