Twenty-year study confirms California forests are healthier when burned -- or thinned

A 20-year experiment in the Sierra Nevada confirms that different forest management techniques -- prescribed burning, restoration thinning or a combination of both -- are effective at reducing the risk of catastrophic wildfire in California.

These treatments also improve forest health, making trees more resilient to stressors like drought and bark beetles, and they do not negatively impact plant or wildlife biodiversity within individual tree stands, the research found. The findings of the experiment, called the Fire Surrogate Study, were published today in the journal Ecological Applications.

"The research is pretty darn clear that these treatments are effective -- very effective," said study lead author Scott Stephens, a professor of fire science at the University of California, Berkeley."I hope this lets people know that there is great hope in doing these treatments at scale, without any negative consequences."

Last year, California announced a strategic plan for expanding the use of prescribed fire to 400,000 acres annually by 2025. However, the use of beneficial fire continues to be hindered by multiple factors, including the lack of a trained workforce, the need for specific weather conditions for burning, and fears about potential risks.

This study shows that restoration thinning is also a viable option for forest management and can be used in tandem with beneficial fire without harming forest health or biodiversity.

"Our findings show that there's not just one solution -- there are multiple things that you can do to impact the risk of catastrophic fire," said study co-author Ariel Roughton, research station manager at Berkeley Forests. "Folks can choose from different combinations of treatments that might fit their needs, and we can show them how those treatments might impact things like wildfire behavior, tree growth and carbon holding in their forests."

Surrogates to wildfire

Over the past two decades, Stephens and other researchers at Berkeley Forests have used prescribed burning, restoration thinning or a combination of both to treat plots of land at Blodgett Forest Research Station, a 4,000-acre experimental forest located about 65 miles northeast of Sacramento on the unceded lands of the Nisenan peoples.

The Fire Surrogate Study was one of 13 studies across the U.S. first launched in 1999 with funding from the U.S. Joint Fire Science Program. Its aim was to study whether the two treatments could mimic the beneficial impacts of lightning fires and Indigenous burning practices on California's forests, which have become dense and overgrown after a century of logging and fire suppression.

"Prescribed fire and restoration thinning are both surrogates for wildfire, a key process that happened frequently in California before European colonization," Stephens said. "The impetus of this study was: If you're going to implement these treatments at a large scale, is there anything that's going to be lost?"

The study created nine experimental plots and three control plots at Blodgett. Three of the experimental plots were managed only using prescribed burns; three burns occurred over the course of 20 years. Three other experimental plots were first thinned and then burned, and the final three were treated only with restoration thinning. The control plots were left to grow without human interference except continued fire suppression.

At the end of the 20-year period, the researchers surveyed the vegetation in each plot and used computational modeling to estimate how many trees were likely to survive wildfire. They found that all three types of experimental plots were significantly more resilient to wildfire than the control plots, showing an 80% likelihood that at least 80% of trees would survive.

They also calculated the "index of competition," a measure of how strongly trees must compete for resources like sunlight, water and soil nutrients. By removing excess trees and vegetation, thinning and burning both limited the amount of competition between trees, making them less vulnerable to stressors, like drought and bark beetles.

However, the plots that were treated with a combination of thinning and fire had the best index of competition, suggesting that they would be the most resilient to the impacts of climate change.

"When you combine thinning with fire, you're able to modify all different levels of the forest structure,and it speeds up the timeline for achieving a more resilient structure," Roughton said.

Restoration thinning can also provide financial benefits: Often, larger trees can be sold to sawmills, and the proceeds can be used to help offset the cost of forest management. Over the course of 20 years, the treatments at Blodgett were entirely paid for by revenue from timber.

"When I go to Sacramento and talk about [forest management] with legislators, the first question they always ask is about cost," Stephens said. "People in the state government are telling us that they can't be the sole source support for this work. That's why the economicsare so important."

Trial by fire

In September 2022, the forests at Blodgett were subjected to a real-life test: On the morning of Sept. 9, 2022, the Mosquito Fire breached the north side of the property, burning approximately 300 acres before it was contained two days later.

One of the study's control plots was located directly in the path of the blaze, and more than 60% of the trees in this plot were completely scorched. However, neighboring experimental plots that had been treated with prescribed burns served as "fuel breaks," burning less hot than the control and acting as staging areas for firefighters.

"We think that, overall, our management actions, coupled with the weather, did have a pretty big impact on the behavior of the fire," Roughton said.

The researchers have received a four-year grant from the Joint Fire Science Program to continue the Fire Surrogate Project. With the help of the grant, they have established a new control plot to replace the one that burned and plan to apply a fourth fire to the experimental burn-only plots.

They are also collaborating with the United Auburn Indian Community to reestablish Indigenous cultural burning at Blodgett.

"We want to be part of the solution, and that's part of our mission at Blodgett," Roughton said. "We hope that by doing these studies and bringing folks here to see the effects of the different treatments, they will take that back and apply it to the land that they're going to be managing."

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First comprehensive look at effects of 2020-2021 California megafires on terrestrial wildlife habitat

The only thing constant is change -- isn't that how the saying goes? We know that wildlife in western forests evolved with changing habitat and disturbances like wildfire. Each species responds differently, some benefiting from openings, others losing critical habitat. What we don't know is how increasing fire severity at large scales is impacting their habitat and survival, because many species are not adapted to these types of "megafires." Researchers at the Rocky Mountain Research Station set about finding some answers. They summarize their findings in "The 2020-2021 California megafires and their impacts to wildlife habitat," a paper that published today in the Proceedings of the National Academy of Sciences.

Why California and why this time period? In 2020 and 2021, California experienced fire activity unlike anything recorded in the modern record.

When the smoke cleared, the amount of burned forest totaled ten times more than the annual average going back to the late 1800s.

Nearly half of the forests that burned experienced high-severity fire, killing 75-100% of the vegetation, and much of this fire covered large continuous areas, rather than a patchy mosaic.

California's Department of Fish and Wildlife curates a comprehensive wildlife database, mapping habitat suitability of hundreds of species across the state.

Coupling that with Forest Service records of wildfires and some fancy computer footwork gave researchers an opportunity to take a broad look at how these types of "megafires" are shaping wildlife habitat within the state.

Jessalyn Ayars, the lead author, said, "Our intent was to take a broad look to gain a better understanding of the impacts of these kinds of fires on wildlife habitat as a whole." She continued, "and since each species is different, this study provides a good jumping-off point for others to be able to focus on a single species of interest or small group of species that share similar habitats."

The fires and habitat studied were mostly located in the Sierra Nevada, southern Cascades, and Klamath mountain regions of California.

Researchers looked at more than 600 wildlife species and found that for 50 species, fires spanned 15-30% of habitat within their range in the state.

One hundred species experience high severity fire over more than 10% of their geographic range within California.

Sixteen of those species are considered species of management concern, such as the great gray owl, wolverine, Pacific marten, and northern rubber boa.

Previous research shows that some species such as great gray owls may benefit from fire in terms of foraging habitat and can be somewhat resilient, but again, the unknown is whether that benefit holds true with this magnitude of habitat change in such a short time.

Some good news is that by looking more closely at some of the details around habitat change by species, scientists learned that these fires are not disproportionately impacting habitats for species of conservation concern compared to wildlife species in general, a finding that suggests that where these species live may serve as refugia for them.

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Historic red tide event of 2020 fueled by plankton super swimmers

A major red tide event occurred in waters off Southern California in the spring of 2020, resulting in dazzling displays of bioluminescence along the coast. The spectacle was caused by exceedingly high densities of Lingulodinium polyedra (L. polyedra),a plankton species renowned for its ability to emit a neon blue glow. While the red tide captured the public's attention and made global headlines, the event was also a harmful algal bloom. Toxins were detected at the height of the bloom that had the potential to harm marine life, and dissolved oxygen levels dropped to near-zero as the extreme biomass of the red tide decomposed. This lack of oxygen led to fish die-offs and other destructive impacts on local ecosystems.

Now, for the first time, a study led by scientists at UC San Diego's Scripps Institution of Oceanography and Jacobs School of Engineering has pinpointed how this plankton species -- a dinoflagellate -- was able to create such an exceptionally dense bloom. The answer lies in dinoflagellates' remarkable ability to swim, which lends them a competitive advantage over other species of phytoplankton. According to the authors, this swimming ability can lead to the formation of dense blooms, including those of the bioluminescent variety.

"The idea that vertical swimming gives dinoflagellates a competitive advantage actually goes back more than half a century, but only now do we have the technology to conclusively prove it in the field," said oceanographer Drew Lucas, senior author of the paper and an associate professor at Scripps Oceanography and the Department of Mechanical and Aerospace Engineering at UC San Diego.

Lucas and former graduate student Bofu Zheng led the work alongside several colleagues in the midst of the red tide event in April and May 2020. The researchers seized the opportunity to deploy sophisticated ocean instruments off the coast of San Diego, resulting in unprecedented measurements. The effort was made possible with funding provided by the Southern California Coastal Ocean Observing System (SCCOOS) through an award by the National Oceanic and Atmospheric Administration (NOAA). The team's findings were published in the Aug. 28 issue of the Proceedings of the National Academy of Sciences, showcased as the cover story.

The dinoflagellates -- L. polyedra specifically -- were shown to be highly mobile, swimming upward during the day to photosynthesize and downward at night to access a deep nutrient pool. This resulted in the intensified ruddy coloration of the water at the surface, hence the term "red tide," seen most prominently in the afternoon. A large population of the dinoflagellates was documented making the downward journey at night, though a portion remained near the surface waters, leading to nighttime displays of bioluminescence. The authors found that this vertical migration is what allowed the dinoflagellates to outgrow their non-mobile competitors, including other species of phytoplankton.

The study validates a 50-year-old hypothesis originally presented by Scripps Oceanography biological oceanographer Richard "Dick" Eppley. He and colleagues posited that the vertical migration of dinoflagellates was linked to harmful algal blooms, which have been documented off Southern California for at least 120 years. Extensive lab research was conducted to support this idea, but it had never been tested in the field until the 2020 event.

As in many dinoflagellate species, L. polyedra is endowed with a pair of flagella -- whip-like appendages that propel the single-celled organism through the water. In addition to its ability to swim, L. polyedra is remarkably fast, with a maximum swimming speed of up to 10 body lengths per second for almost 24 hours.

"In the plankton world, they are Michael Phelps," said Lucas, describing the dinoflagellates. "For comparison, fast-burst swimming in species like bluefin tuna or shortfin mako is around 9-10 body lengths per second, but only for very short periods. Their exceptional swimming allows L. polyedra to dive to cold depths where they can take up nutrients, allowing these organisms to really bloom and explode in population."

The team used the Wirewalker -- an autonomous, ocean-wave-powered vertical profiling system that was developed at Scripps Oceanography -- to continuously measure physical and biochemical conditions from the sea surface to the seafloor, reaching a depth of 100 meters (300 feet). Powered by wave energy, the instrument moves up and down a mooring line attached to a buoy, while taking measurements of temperature, salinity, depth, sunlight levels, chlorophyll fluorescence, and nitrate concentrations. They also captured near-surface images of the bloom using an Imaging FlowCytobot (IFCB), a robotic microscope installed on an offshore mooring; this site is now part of a larger IFCB network overseen by SCCOOS.

Data and images collected by these instruments validated Eppley's original hypothesis, showing that indeed L. polyedra descended at dusk, reaching a maximum depth of about 30-40 meters (100-130 feet) after 18 to 24 hours of swimming. While in the deep, the dinoflagellates would take up nitrate, which acts as a growth nutrient for plankton, before returning to the surface around noon to photosynthesize during maximum sunlight.

The growth of phytoplankton biomass, or the "bloom," correlated with proportional decreases in nitrate concentrations at depth, linking the important role that swimming phytoplankton have in the development of certain types of red tides. On cloudy days, the subsurface vertical migration was much less apparent, suggesting that the intensity of sunlight is an important trigger for vertical migration.

Lead author Zheng, now a postdoctoral investigator at Woods Hole Oceanographic Institution (WHOI), was impressed by the many advanced functions of the dinoflagellates, which are comparable in size to the diameter of a human hair.

"These single-celled organisms, namely L. polyedra, are so functionally complex and amazing," said Zheng. "In addition to their swimming speed, which is far beyond human limits, they can coordinate their behavior according to the day-night cycle by migrating down at night and coming back to the ocean surface during the day; they can produce spectacular bioluminescence; they can photosynthesize; they can even prey on organisms that are smaller than them."

The researchers also looked at long-term ocean monitoring data captured by the California Cooperative Oceanic Fisheries Investigations (CalCOFI), and long-term mooring data maintained by the Ocean Time-Series Group at Scripps Oceanography to see other consequences from the bloom. Looking at more than 70 years of climate data, the results showed that the bloom created physical and chemical conditions in the water column that deviated from the norm, showing the potential for massive blooms to alter characteristics of the coastal ocean.

Study co-author and SCCOOS director Clarissa Anderson said this research stands out for its use of novel ocean technologies, which allowed for unparalleled measurements of how phytoplankton respond to small-scale changes in the coastal ocean, as well as calculations of nutrient uptake by dinoflagellates at such fine scales. She also noted the importance of long-term observations as being key to any future efforts to better understand harmful algal blooms.

"The more we understand complex mechanisms that allow a particular species or population of plankton to thrive and persist, the better we can predict runaway events like the 2020 red tide that lasted much longer than theory might dictate," said Anderson, who is also a biological oceanographer at Scripps Oceanography. "With longer time series of rapid change in coastal nutrient delivery, circulation, light regimes, and algal toxins, we could build more accurate dynamical models for predicting plankton blooms, including those that turn harmful."

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Scientists zero in on timing, causes of ice age mammal extinctions in southern California

The end of the last Ice Age also marked the end for more than three dozen genera of large mammals in North America, from mammoths and mastodons to bison and saber-toothed cats. Details concerning the precise timing and circumstances, however, have remained murky ever since.

A team of scientists that included Texas A&M University archaeologist Dr. Michael Waters recently focused on the well-known Rancho La Brea Tar Pits in southern California in their quest to provide answers to these questions, resulting in the most exact and detailed timeline for the extinctions that happened during the latter part of the Pleistocene period in North America, along with some foreboding insight into the area's present and future. Their work is featured on the cover of the current issue of Science.

Waters, a distinguished professor in the Department of Anthropology and director of the Center for the Study of the First Americans (CSFA), along with roughly a dozen fellow researchers, examined the timing and cause of the extinction of a variety of large mammals, known as megafauna, that got stuck in tar at Rancho La Brea, ensuring the preservation of their bones. The team used the radiocarbon dating method to date 169 bones from seven different animals -- bison, horse, camel and ground sloths as well as the carnivores that ate them, including the saber-toothed cat, dire wolf and American lion. They also compared those findings to regional pollen and charcoal records along with continent-wide data on human and large mammal populations.

Armed with their new data, the researchers subsequently used time-series modeling to produce the most detailed chronobiology to date, showing the relationships between climate and vegetation change, fire activity, human demographics and megafauna extinctions -- groundbreaking results they report in the Aug. 18 edition of the world-leading academic journal.

Waters says the team's findings reveal that Ice Age mammal populations in southern California were steady from 15,000 to around 13,250 years ago. Afterward, there was a sharp decline in the population of the seven animals studied, and they all became extinct between 13,070 to 12,900 years ago.

In an interesting modern-day parallel, this extinction event corresponds with a change in the environment from 13,300 to 12,900 years ago marked by warming and drying that made the land more vulnerable to fires in southern California. Charcoal records show that fires increased around 13,500 years ago and peaked between 13,200 and 12,900 years ago. Studies show that humans arrived in North America's Pacific coast 16,000 to 15,000 years ago and lived alongside the megafauna for 2,000 to 3,000 years before their extinction.

While humans hunted animals during this period, Waters says the impact of hunting on the demise of the megafauna likely was minor because of the low population of humans on the landscape. However, the fires would have been devastating, resulting in the loss of habitat causing the rapid decline and extinction of the megafauna in southern California. The study suggests these fires were ignited by humans, which had increased in number by that time.

"Fire is a way that small numbers of humans can have a large impact over a broad area," said Waters, who also cautions that climate changes observed in present-day California are similar to those of the late Pleistocene.

"This study has implications for the changes we see in southern California today," Waters added. "The temperatures are rising, and the area is drying. We also see a dramatic increase in fires. It appears that history may be repeating itself."

While Waters acknowledges that this is the story of extinction at Rancho La Brea, he says it has the potential to offer insights into when extinctions happened across all of North America.

"Mammoths and mastodons survived in many parts of North America until around 12,700 years ago," he added. "These animals were hunted by the Clovis people between about 13,000 and 12,700 years ago. We are now dating megafauna remains from other locations to give a broader understanding of the Rancho La Brea research in the context of North America."

The museum at La Brea Tar Pits holds the world's largest collection of fossils from the Ice Age and has been central to the study of animal and plant life at the end of the Pleistocene epoch for more than a century. Its naturally occurring asphalt pools entrapped and preserved the bones of thousands of individual animals representing dozens of megafaunal species during the last 60,000 years, enabling scientists to determine when different species disappeared from the ecosystem and why.

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Preserving forests to protect deep soil from warming

A recent study led by scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of Zurich has revealed that the organic compounds proposed for carbon sequestration in deep soil are highly vulnerable to decomposition under global warming.

The finding has implications for a key strategy in carbon management that relies on soil and forests -- natural carbon "sinks" -- to mitigate global warming.

About 25 percent of global carbon emissions are captured by forests, grasslands, and rangelands. During photosynthesis, plants store carbon in their cell walls and in the soil. Because of rich carbon stores from decades past, soils contain twice as much carbon as the atmosphere does, and deeper subsoils (more than 8 inches or 20 centimeters) account for roughly half of the soil carbon. But as global populations rise, so do our demands for new croplands and timber. Research shows that disturbing the natural world for commerce has a price: the United Nations' Intergovernmental Panel on Climate Change has warned that emissions from deforestation and agriculture account for around a fifth of global greenhouse gases.

"Our study shows that climate change will affect all aspects of soil carbon and nutrient cycling. It also shows that in terms of carbon sequestration, there's no silver bullet. If we want soil to sustain carbon sequestration in a warming world, we will need better soil management practices, which can mean minimal disturbance of soils during forest management and agriculture," said Margaret Torn, a senior scientist in Berkeley Lab's Earth & Environmental Sciences Area and a senior author of the study.

In 2021, Torn and her research team provided the first physical evidence that warmer temperatures lead to a significant drop in the carbon stocks stored in deep forest soils -- a loss of 33% over five years.

In the new study, Torn and first author Cyrill Zosso of the University of Zurich unveil a clearer picture of soil in a warming world. This time, the research team is the first to show that warmer temperatures lead to a significant drop in the soil organic carbon compounds that are created by plants during photosynthesis.

During an experiment at the University of California's Blodgett Forest Research Station in the foothills of California's Sierra Nevada mountains, the researchers used vertical heating rods to continuously warm 1-meter-deep (three-foot-deep) plots of soil by 4 degrees Celsius (7 degrees Fahrenheit). That is the amount of warming projected by the end of the 21st century if greenhouse gas emissions remain high.

They found that just 4.5 years of warming at this temperature led to large changes in carbon stocks at a depth of more than 30 centimeters (or approximately 12 inches) below the soil surface.

During spectroscopic experiments at the University of Zurich, Zosso identified the organic compounds that were affected by the warming.

The results were shocking: a 17% loss in lignin -- the compounds that give plants rigidity -- and a nearly 30% loss in cutin and suberin, the waxy compounds in leaves, stems, and roots that protect plants from pathogens.

Torn and Zosso were also surprised to find a significant difference in the amount of "pyrogenic carbon" in the soil samples that were artificially heated versus the ones that were not. Pyrogenic carbon is a type of soil organic carbon derived from charred vegetation and other organic matter remnants left in the wake of a wildfire.

Many researchers assume that pyrogenic carbon has the most potential to serve as a very stable form of sequestered carbon. "We found much less pyrogenic carbon in the deep soils when they were heated," Torn said.

"Pyrogenic carbon can stay in the soil for decades or even centuries, but we need to understand its vulnerability to warming or to changes in land management. Our study suggests that this material decomposed just as fast as anything else would when the soil was warmed," Torn explained. "This shows that when you put material deep into soil where it's in contact with minerals and microbes, those natural systems will decompose the material over time."

The researchers next plan to resample soil from the study to determine how nine years of warming impact soil composition and health. A new grassland warming experiment at the Point Reyes National Seashore in Northern California is also on the horizon. "We are also organizing all the world's deep-soil warming (or whole-soil warming) experiments to share data and know-how and conducting synthesis of the data to see what we can learn," Torn said.

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Drought, heat waves worsen West Coast air pollution inequality

A new study led by North Carolina State University researchers found drought and heat waves could make air pollution worse for communities that already have a high pollution burden in California, and deepen pollution inequalities along racial and ethnic lines.

Published in Nature Communications, the study also found financial penalties for power plants can significantly reduce people's pollution exposure, except during severe heat waves.

"We have known that air pollution disproportionally impacts communities of color, the poor and communities that are already more likely to be impacted by other sources of environmental pollution," said the study's lead author Jordan Kern, assistant professor of forestry and environmental resources at NC State. "What we know now is that drought and heat waves makes things worse."

For the study, researchers estimated emissions of sulfur dioxide, nitrogen oxides and fine particulate matter from power plants in California across 500 different scenarios for what the weather could look like in future years, which they called "synthetic weather years." These years simulated conditions that could occur based on historical wind, air, temperature and solar radiation values on the West Coast between 1953 and 2008. Then by using information about the location of power plants in California and how much electricity they would be generating under different weather conditions, they estimated air pollution within individual counties.

They saw the worst air pollution in the hottest, driest years, which Kern said is due to the demand for more air conditioning during hot years. In addition, drought can impact the availability of hydropower. The excess electricity has to come from somewhere else, which is where fossil fuel plants come in.

"One of the things we were interested in was teasing apart the relative roles of drought, which can be chronic, lasting for months or years, versus heat waves, which can happen like a flash in a pan," Kern said. "We found drought is a driver of chronic pollution exposure, but heat waves are responsible for these incredible spikes in emissions in a short period of time."

They also saw that counties with a higher existing pollution burden were disproportionately impacted by pollution during drought and heat waves. Counties that were more diverse by race and ethnicity were also far more likely to be impacted by increased emissions from power plants during droughts and heat waves.

"The more diverse your county is by race and ethnicity, the more likely you are to be impacted by air pollution on an annual basis," Kern said. "During a drought, the relationship is more pronounced."

When they simulated the impact of three different policies that taxed power generators for emitting air pollution locally, overall, or both, they found that penalties helped reduce pollution health damages in more than 99% of days. However, during extreme heat waves, penalties failed to reduce emissions.

"Penalties make the more damaging power plants more expensive to operate, while it makes clean power plants comparatively less expensive," Kern said. "It incentivizes the system to switch to rely on more clean power plants, but that stops happening during really massive heat waves. The power operators have no choice but to turn on every power plant. They can't switch from the dirty power plants to the clean ones."

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Climate whiplash increased wildfires on California's west coast about 8,000 years ago

Scientists are trying to uncover and analyze evidence from the past in their search for a better assessment of future climate trends. In a joint international research project, researchers have been studying the effects of the sudden decrease in global temperatures that occurred about 8,200 years ago, the so-called 8.2-kiloyear event, with the help of mineral deposits present in White Moon Cave in Northern California. New indications show that oscillations between extreme wetness and aridity in California were closely linked with the occurrence of wildfires. The participating researchers from Johannes Gutenberg University Mainz (JGU) in Germany, Vanderbilt University in Nashville, USA, and Northumbria University in Newcastle upon Tyne in the UK have concluded that such events are likely to become more common in the face of human-induced climate change. The corresponding article has been published recently in Nature Communications.

Stalagmites as a valuable archive of climate data

Climate change and its effects on our seasons, water resources, vegetation, and soil have already become clearly apparent. The rate and intensity of wildfires in semi-arid regions, such as those in the west of North America, already exceed those that might be expected in view of the historical records.

To be able to predict future scenarios, it is helpful to better understand the climate of the past. There are readily datable climate archives that reach back many thousands of years that preserve traces of chemical compounds. These compounds provide insight into continental and regional climatic changes and the prevailing environmental conditions. One of the most easily datable and detailed climate archives of this kind is provided by various forms of mineral deposits, known as speleothems, which accumulate in caves. Stalagmites are of particular interest in this connection because of their uniform growth pattern.

By analyzing the content of two novel marker substances, i.e., levoglucosan and lignin oxidation products (LOPs), in a stalagmite, the team of researchers from Mainz, Nashville, and Newcastle have been able to reconstruct fire activity and vegetation composition in the California Coast Range during the 8.2-kiloyear event. This cold phase lasted several hundred years. Evidence of the event was first detected in the analysis of pollen in early Holocene deposits in the Swiss Alps and later also in ice cores obtained in Greenland. The results of further studies indicate that precipitation rates in western North America at this time were much more variable than usual. Erratic climate-related swings of this type are characteristic of a phenomenon called climate whiplash. Many scientists share the opinion that we will see more climate whiplash events as a consequence of global warming.

Hydroclimate fluctuations result in more fire activity and more woody vegetation

"The results we have now published suggest that both vegetation composition and wildfire activity were directly linked to this climate whiplash event," explained Julia Homann, a doctoral candidate in the research group of Professor Thorsten Hoffmann at Mainz University. Elevated concentrations of levoglucosan indicate increased fire activity, while altered LOP compositions represent a shift towards more tree-like vegetation during the 8.2-kiloyear event. The detected changes were direct consequences of a profound climate whiplash, in other words, stronger hydroclimate fluctuations.

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Why the Salton Sea is turning into toxic dust

The Salton Sea, California's most polluted inland lake, has lost a third of its water in the last 25 years. New research has determined a decline in Colorado River flow is the reason for that shrinking.

As the lake dries up, the concentration of salt and chemicals in the remaining water has increased dramatically, causing a mass die-off of fish and birds, including endangered species. The dry lakebed, coated in the salty, toxic water, becomes dust that causes respiratory problems for nearby residents.

"It is an environmental catastrophe," said Juan S. Acero Triana, UCR hydrologist and lead author of a new study focused on understanding water movement on and below Earth's surface near the Salton Sea, a research field called hydrology. The study was funded by the National Science Foundation's Innovation at the Nexus of Food, Energy and Water Systems, or INFEWS, program.

There have been a variety of hypotheses about why the water levels are steadily declining. Some blame climate change and heat for drying up the lake. Others suspect that agriculture could be to blame. As irrigation systems get more efficient and crops are modified to use less water, it means less water getting into the Salton Sea. However, the researchers say these are not the biggest causes of the sea's decline.

"There is less water coming from the Colorado River into the Sea, and that is driving the problem," said Hoori Ajami, UCR hydrologist, study co-author and principal investigator. This finding, and the methods used to obtain it, are now published in the journal Water Resources Research.

The researchers considered all major processes impacting the water balance of an endorheic lake like the Salton Sea, where water flows in but not out to any tributaries. Endorheic lakes worldwide have been shrinking in recent decades at what the researchers call an "alarming" rate due to the combined effects of global warming and diversion of water for agricultural and industrial purposes.

To understand the reasons for the Salton Sea's decline, the researchers used a hydrologic model that accounted for all processes in the surrounding areas that impact the lake's water balance, including climate, soil types, land slope, and plant growth.

Geographically the model included data not only about the Sea itself, but also from the surrounding watershed, streams entering the lake, and the land area that drains into those streams.

Data for the model was hard to come by as this is a transboundary basin on the US-Mexico border between California and Baja California Norte, and stakeholders may have been reluctant to share data that could alter previously earned water rights. However, using publicly available data and data mining techniques, UCR researchers were able to simulate long-term water balance dynamics and identify reduced Colorado River flows as the main cause of the Salton Sea shrinking.

"It's not entirely clear, however, whether the decline in Colorado River water is more due to global warming drying out the river, or reductions in allocation levels to California, or both," Acero Triana said.

Despite that lingering ambiguity, the researchers say the study should send a message to water management agencies and lawmakers that the Salton Sea watershed should be considered part of the Colorado River basin.

Read more at Science Daily

Air pollution, including during wildfires, shows ill effects in children

New research linking air pollution data from federal monitors in the Sacramento area of California, including during significant fires, is showing ill effects of pollution exposure among children, a new University of California, Davis, study suggests.

Blood samples show that children have elevated markers of inflammation, such as interleukin 6, if they were exposed to higher air pollution. Further, higher air pollution was linked to lower cardiac autonomic regulation in children, which impacts how fast the heart beats and how hard it pumps, according to the study.

In the study, published Aug. 3 date in the journal New Directions for Child and Adolescent Research, researchers looked at blood samples from more than 100 healthy children ages 9-11 in the Sacramento area where pollutants near their homes were recorded by the Environmental Protection Agency. The study was authored by Anna M. Parenteau, a doctoral student, and Camelia E. Hostinar, associate professor, both from the UC Davis Department of Psychology. The work took place at UC Davis.

These findings are important because exposure to pollutants released during wildfires has been related to numerous negative health outcomes in children, who have smaller bodies and organ systems than adults, including asthma and decreased lung function, as well as neurodevelopmental outcomes like attention deficit hyperactivity disorder, autism, and deficits in school performance and memory, researchers said.

Looked at particulates

Researchers looked at fine particulate matter data from the EPA (PM2.5) -- or the fine particles that can penetrate lungs and pass into the bloodstream -- finding the children's blood contained markers of systemic inflammation. Additionally, PM2.5, which refers to particulate matter measuring 2.5 micrometers or smaller by the EPA, was linked to lower cardiac autonomic regulation assessed using an electrocardiogram. Specifically, researchers used data files maintained by the EPA, which have daily air quality summary information from each outdoor monitor in the country.

In total, 27 of the children studied had inflammation markers in their blood recorded during significant fires when their neighborhoods recorded significant levels of PM2.5 in the air. These times when fires were burning included during the Mendocino Complex Fire in 2018, which was active about 100 miles from the lab where blood was drawn. The findings were similar to those found in an earlier study, in which the blood of young primates was collected by UC Davis researchers after significant wildfires.

"By examining daily and monthly levels of particulate matter in relation to children's inflammation and autonomic physiology, this study further demonstrates the immediate consequences of exposure to air pollution, which may increase risk of future disease," Parenteau said. Furthermore, Parenteau added: "As climate change continues to impact children and families, it is paramount to understand the impact of environmental contaminants such as air pollution on children's physiology."

Previous studies with children have shown significant associations between ambient air pollution and allergic sensitization, respiratory symptoms, and ultra-structural and cellular changes to their lungs and airways, researchers said.

Researchers have found children may be especially susceptible to the effects of air pollution, given that, compared to adults, they have a higher intake of contaminants and greater lung surface area relative to their body weight.

Continued developmental research on environmental contaminants can sound the alarm about the effects of air pollution and inform policy changes that could promote long-term population health, researchers concluded.

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Bay Area storms get wetter in a warming world

The December 2014 North American Storm Complex was a powerful winter storm, referred to by some as California's "Storm of the Decade." Fueled by an atmospheric river originating over the tropical waters of the Pacific Ocean, the storm dropped 8 inches of rainfall in 24 hours, sported wind gusts of 139 miles per hour, and left 150,000 households without power across the San Francisco Bay Area.

Writing in Weather and Climate Extremes this week, researchers described the potential impacts of climate change on extreme storms in the San Francisco Bay area, among them the December 2014 North American Storm Complex.

Re-simulating five of the most powerful storms that have hit the area, they determined that under future conditions some of these extreme events would deliver 26-37% more rain, even more than is predicted simply by accounting for air's ability to carry more water in warmer conditions.

However, they found these increases would not occur with every storm, only those that include an atmospheric river accompanied by an extratropical cyclone.

The research -- funded by the City and County of San Francisco and in partnership with agencies including the San Francisco Public Utilities Commission, Port of San Francisco, and San Francisco International Airport -- will help the region plan its future infrastructure with mitigation and sustainability in mind.

"Having this level of detail is a game changer," said Dennis Herrera, General Manager of the San Francisco Public Utilities Commission, which was the lead City agency on the study. "This groundbreaking data will help us develop tools to allow our port, airport, utilities, and the City as a whole to adapt to our changing climate and increasingly extreme storms."

These first-of-their-kind forecasts for the city were made possible by the Stampede2 supercomputer at the Texas Advanced Computing Center (TACC) and the Cori system at the National Energy Research Scientific Computing Center (NERSC) -- two of the most powerful supercomputers in the world, supported by the National Science Foundation and Department of Energy respectively.

Hindcasting With the Future in Mind

Certain facets of our future climate are well established -- higher temperatures, rising seas, species loss. But how will greater greenhouse gas concentrations and warmer air and oceans effect extreme weather, like hurricanes, tornadoes, and heavy rainfall? And where precisely will these changes be the greatest and under what conditions?

Forecasting the natural hazards of the future is the mission of Christina Patricola, Assistant Professor of Geological and Atmospheric Sciences at Iowa State University and lead author on the Weather and Climate Extremes paper. Her research helps quantify and understand the risks we face from natural hazards in the future.

Using supercomputers allowed Patricola to model the region with 3 kilometer resolution. Scientists believe this level of detail is needed to capture the dynamics of storm systems like hurricanes and atmospheric rivers, and to predict their impact on an urban area.

For each of the historical storms, Patricola and her collaborators ran 10-member ensembles -- independent, slightly different simulations -- with 3 kilometer resolution, a process called 'hindcasting' (as opposed to forecasting). They then adjusted the greenhouse gas concentrations and sea-surface temperatures to predict how these historical storms would look in the projected future climates of 2050 and 2100.

Patricola calls these "storyline" experiments: computer models that are meant to be instructive for thinking about how historically-impactful storm events could look in a warmer world. Focusing on events that were known to be impactful to city operations provides a useful context for understanding the potential impacts of events if they occurred under future climate conditions.

The study doesn't address changes in the frequency of extreme storms in the future and therefore can't address how precipitation will change overall, she said. (Another pressing question for California planners.) But they can help decision-makers understand trends in the intensity of the worst-case-scenario storms and make informed choices.

On the West Coast, much of the precipitation that falls is associated with atmospheric rivers (ARs), which transport a substantial amount of moisture in a narrow band, Patricola explained. Some of the storms they looked at featured ARs alone. Others had ARs at the same time as low-pressure systems known as extratropical cyclones (ETCs).

"We found something very interesting," she said. "Precipitation increased substantially for events with an atmospheric river and a cyclone together, whereas precipitation changes were weak or negative when there was only an atmospheric river."

The difference, she believes, lies in the lifting mechanism. In general, heavy precipitation requires moist air to ascend. While the AR-only storms showed a future increase in atmospheric moisture, the storms with an AR and ETC showed a future increase in atmospheric moisture and rising air. Additional investigations will explore this relationship.

High Performance Climate Science

Patricola has used TACC supercomputers for climate and weather modeling since 2010, when she was a graduate student at Cornell University working with leading climate scientist, Kerry Cook (now at The University of Texas at Austin). She recalls that her first models had a horizontal resolution of 90 km -- 30 times less resolved than today -- and were considered state-of-the-art at the time.

"It was a very big help to have the resource from TACC and NERSC for these simulations," she said. "We're interested in extreme precipitation totals and hourly rainfall rates. We had to go to a high resolution of 3 km to make these predictions. And as we increase resolution, the computational expense goes up."

Patricola has used the methodology she developed to understand other phenomena, like how tropical cyclones may change in the future. She and collaborator Michael Wehner reported on these changes in a 2018 Nature paper. "If a hurricane like Katrina happened at the end of the 21st century, what could it be like? More rainfall, higher winds? Our method can be used for any type of weather system that can be hindcasted."

In the next phase of the San Francisco project, Patricola will work with city staff and their collaborators to understand what the weather changes mean in terms of city operations.

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Archaeological dig reveals participants in California’s Gold Rush dined on salted Atlantic cod

It turns out San Francisco has been a destination for lovers of imported delicacies since its earliest Gold Rush days.

According to results published recently in the peer-reviewed Journal of Anthropological Research, an excavation at Thompson's Cove in San Francisco has shown "Atlantic cod were imported during the 1850s, likely as a (largely) deboned, dried and salted product from the East Coast of the United States." The results underscore the importance of global maritime trade in northern California during the Gold Rush.

Co-author Brittany Bingham, doctoral student in anthropology at the University of Kansas, performed genetic analysis on 18 cod bones recovered from Thompson's Cove to determine if they came from cod caught in the deep nearby waters of the Pacific or were shipped in packages by boat from Atlantic fisheries. Her results on five specimens for ancient DNA show Atlantic cod were imported during the debut of the Gold Rush.

Bingham said bones tend to be better preserved and more suitable for analysis than other materials left behind from the rapid surge in San Francisco's population. (In the first year of the Gold Rush, between 1848-49, the area's 800 residents quickly swelled to more than 20,000.)

"Bones preserve better than other things that don't last in the archaeological record as well," she said. "You won't get a quality DNA sample from every bone -- some are burned, and soil and other factors can affect preservation, so we typically check for DNA and determine what we're looking at. But often people move bones elsewhere and maybe they're thrown in a different place than the rest of the bones, so you don't have the whole specimen to look at. That's where people like me come into play, and we'll take the one tiny piece of bone that might have been found and figure out what it actually came from."

The results of Bingham's analysis were among the first archaeological results to confirm findings from historical newspapers and invoices: The early history of San Francisco included the importation of a wide range of fish and seafood to support the population boom.

The project came about when the Musto Building built in 1907 at Thompson's Cove -- where the city was first settled -- undertook a mandatory retrofitting to be more resilient to earthquakes, triggering a California compliance law requiring archaeological work in conjunction with construction at the site. Today, the building is home to a private social club.

Kale Bruner, who earned her doctorate in anthropology at KU, worked on the Thompson's Cove site as construction took place. Today, Bruner serves as a research associate at the Museum of the Aleutians.

"Compliance work is challenging in a lot of ways because you don't really get a lot of control over the excavations, and this case was kind of an extreme example of that -- the fieldwork conditions were overwhelming -- and I was the only archaeologist on site," Bruner said. "They were fortunately only excavating dirt in one location at a time, so I only had one piece of machinery to be watching, but we were hitting archaeologically significant material constantly. It was two years essentially of monitoring that kind of activity and documenting as rapidly as possible everything that was being uncovered."

Aside from evidence of Atlantic cod, the authors reported about 8,000 total specimens or fragments of animal bone, and a total number of artifacts collected that numbered nearly 70,000. The work will yield more academic papers on the historical significance of the site.

Lead author Cyler Conrad, adjunct assistant professor of anthropology at the University of New Mexico and archaeologist with Los Alamos National Laboratory, has published other findings from work at Thompson's Cove, including evidence of a California hide and tallow trade, eating of wild game, hunting of ducks and geese, and even importation of Galapagos tortoise.

He described the Gold Rush era as exciting and chaotic, a time that in some ways mirrored the supply chain problems plaguing the world in the COVID-19 era.

"During the Gold Rush, it took many months for vessels to arrive in San Francisco, so often when you needed things is not when they would arrive, and when things would arrive, they were often not needed anymore," Conrad said. "You find these descriptions of San Francisco as this kind of muddy mess, a kind of a tent city where there were shacks built upon shacks all the way up until the shoreline, just stacked with crates and boxes. Even at Thompson's Cove, I think Kale excavated several essentially intact crates of frying pans and shovel heads. You can imagine shiploads of shovels might arrive, but maybe everyone had a shovel already or maybe it was winter, and no one was in the gold fields and you have all this material that accumulates right along the shoreline -- but that was convenient for our work."

Conrad said the work to determine the Atlantic origins of cod bones found at the site was a significant contribution to understanding maritime trade of the era, when Atlantic cod was either shipped by boat all the way around Cape Horn -- or shipped to Panama, then hauled across the isthmus, before being shipped up to the Northern California gold fields.

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California's rainy season starting nearly a month later than it did 60 years ago

 The start of California's annual rainy season has been pushed back from November to December, prolonging the state's increasingly destructive wildfire season by nearly a month, according to new research. The study cannot confirm the shift is connected to climate change, but the results are consistent with climate models that predict drier autumns for California in a warming climate, according to the authors.

Wildfires can occur at any time in California, but fires typically burn from May through October, when the state is in its dry season. The start of the rainy season, historically in November, ends wildfire season as plants become too moist to burn.

California's rainy season has been starting progressively later in recent decades and climate scientists have projected it will get shorter as the climate warms. In the new study, researchers analyzed rainfall and weather data in California over the past six decades. The results show the official onset of California's rainy season is 27 days later than it was in the 1960s and the rain that does fall is being concentrated during the months of January and February.

"What we've shown is that it will not happen in the future, it's happening already," said Jelena Luković, a climate scientist at the University of Belgrade in Serbia and lead author of the new study. "The onset of the rainy season has been progressively delayed since the 1960s, and as a result the precipitation season has become shorter and sharper in California."

The new study in AGU's journal Geophysical Research Letters, which publishes high-impact, short-format reports with immediate implications spanning all Earth and space sciences, is the first to quantify just how much later the rainy season now begins.

The results suggest California's wildfire season, which has been getting progressively worse due to human-caused climate change, will last even longer in the years to come and Californians can expect to see more fires flaring up in the month of November. 2020 was California's worst wildfire season on record, with nearly 10,000 fires burning more than 4.2 million acres of land.

An extended dry season means there is more overlap between wildfire season and the influx of Santa Ana winds that bring hot, dry weather to California in the fall. These winds can fan the flames of wildfires and increase the risk of late-season fires getting out of hand.

"It's not just a matter of making the vegetation drier and keeping all else equal," said Daniel Swain, a climate scientist at the University of California Los Angeles who was not involved in the study. "You're also increasing the number of opportunities for extremely dry vegetation and extremely strong offshore winds to coincide."

The delay in the start of the rainy season is likely due to changes in the atmospheric circulation patterns that bring precipitation to the West Coast, according to the study authors. They found the atmospheric circulation pattern that dominates California during the summer is extending into fall across the north Pacific Ocean. This change is bringing more rain to the states of Washington and Oregon and leaving California high and dry.

The changes mean Californians will need to better plan how they manage water resources and energy production -- a longer dry season means more irrigation is needed for crops in an already water-stressed state.

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Simulating 800,000 years of California earthquake history to pinpoint risks

 Massive earthquakes are, fortunately, rare events. But that scarcity of information blinds us in some ways to their risks, especially when it comes to determining the risk for a specific location or structure.

"We haven't observed most of the possible events that could cause large damage," explained Kevin Milner, a computer scientist and seismology researcher at the Southern California Earthquake Center (SCEC) at the University of Southern California. "Using Southern California as an example, we haven't had a truly big earthquake since 1857 -- that was the last time the southern San Andreas broke into a massive magnitude 7.9 earthquake. A San Andreas earthquake could impact a much larger area than the 1994 Northridge earthquake, and other large earthquakes can occur too. That's what we're worried about."

The traditional way of getting around this lack of data involves digging trenches to learn more about past ruptures, collating information from lots of earthquakes all around the world and creating a statistical model of hazard, or using supercomputers to simulate a specific earthquake in a specific place with a high degree of fidelity.

However, a new framework for predicting the likelihood and impact of earthquakes over an entire region, developed by a team of researchers associated with SCEC over the past decade, has found a middle ground and perhaps a better way to ascertain risk.

A new study led by Milner and Bruce Shaw of Columbia University, published in the Bulletin of the Seismological Society of America in January 2021, presents results from a prototype Rate-State earthquake simulator, or RSQSim, that simulates hundreds of thousands of years of seismic history in California. Coupled with another code, CyberShake, the framework can calculate the amount of shaking that would occur for each quake. Their results compare well with historical earthquakes and the results of other methods, and display a realistic distribution of earthquake probabilities.

According to the developers, the new approach improves the ability to pinpoint how big an earthquake might occur in a given location, allowing building code developers, architects, and structural engineers to design more resilient buildings that can survive earthquakes at a specific site.

"For the first time, we have a whole pipeline from start to finish where earthquake occurrence and ground-motion simulation are physics-based," Milner said. "It can simulate up to 100,000s of years on a really complicated fault system."

Applying massive computer power to big problems

RSQSim transforms mathematical representations of the geophysical forces at play in earthquakes -- the standard model of how ruptures nucleate and propagate -- into algorithms, and then solves them on some of the most powerful supercomputers on the planet. The computationally-intensive research was enabled over several years by government-sponsored supercomputers at the Texas Advanced Computing Center, including Frontera -- the most powerful system at any university in the world -- Blue Waters at the National Center for Supercomputing Applications, and Summit at the Oak Ridge Leadership Computing Facility.

"One way we might be able to do better in predicting risk is through physics-based modeling, by harnessing the power of systems like Frontera to run simulations," said Milner. "Instead of an empirical statistical distribution, we simulate the occurrence of earthquakes and the propagation of its waves."

"We've made a lot of progress on Frontera in determining what kind of earthquakes we can expect, on which fault, and how often," said Christine Goulet, Executive Director for Applied Science at SCEC, also involved in the work. "We don't prescribe or tell the code when the earthquakes are going to happen. We launch a simulation of hundreds of thousands of years, and just let the code transfer the stress from one fault to another."

The simulations began with the geological topography of California and simulated over 800,000 virtual years how stresses form and dissipate as tectonic forces act on the Earth. From these simulations, the framework generated a catalogue -- a record that an earthquake occurred at a certain place with a certain magnitude and attributes at a given time. The catalog that the SCEC team produced on Frontera and Blue Waters was among the largest ever made, Goulet said. The outputs of RSQSim were then fed into CyberShake that again used computer models of geophysics to predict how much shaking (in terms of ground acceleration, or velocity, and duration) would occur as a result of each quake.

"The framework outputs a full slip-time history: where a rupture occurs and how it grew," Milner explained. "We found it produces realistic ground motions, which tells us that the physics implemented in the model is working as intended." They have more work planned for validation of the results, which is critical before acceptance for design applications.

The researchers found that the RSQSim framework produces rich, variable earthquakes overall -- a sign it is producing reasonable results -- while also generating repeatable source and path effects.

"For lots of sites, the shaking hazard goes down, relative to state-of-practice estimates" Milner said. "But for a couple of sites that have special configurations of nearby faults or local geological features, like near San Bernardino, the hazard went up. We are working to better understand these results and to define approaches to verify them."

The work is helping to determine the probability of an earthquake occurring along any of California's hundreds of earthquake-producing faults, the scale of earthquake that could be expected, and how it may trigger other quakes.

Support for the project comes from the U.S. Geological Survey (USGS), National Science Foundation (NSF), and the W.M. Keck Foundation. Frontera is NSF's leadership-class national resource. Compute time on Frontera was provided through a Large-Scale Community Partnership (LSCP) award to SCEC that allows hundreds of U.S. scholars access to the machine to study many aspects of earthquake science. LSCP awards provide extended allocations of up to three years to support long-lived research efforts. SCEC -- which was founded in 1991 and has computed on TACC systems for over a decade -- is a premier example of such an effort.

The creation of the catalog required eight days of continuous computing on Frontera and used more than 3,500 processors in parallel. Simulating the ground shaking at 10 sites across California required a comparable amount of computing on Summit, the second fastest supercomputer in the world.

"Adoption by the broader community will be understandably slow," said Milner. "Because such results will impact safety, it is part of our due diligence to make sure these results are technically defensible by the broader community," added Goulet. But research results such as these are important in order to move beyond generalized building codes that in some cases may be inadequately representing the risk a region face while in other cases being too conservative.

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California's 2018 wildfires caused $150 billion in damages

 In 2018, California wildfires caused economic losses of nearly $150 billion, or about 0.7 percent of the gross domestic product of the entire United States that year, and a considerable fraction of those costs affected people far from the fires and even outside of the Golden State.

For a study to be published Monday, Dec. 7, in Nature Sustainability, researchers at the University of California, Irvine, China's Tsinghua University and other institutions combined physical, epidemiological and economic models to gain a more comprehensive understanding of the impact of the blazes. More than 8,500 separate fires burned 1.9 million acres, making them the deadliest and most destructive in any year in California history.

Tallying the damage, the team found that direct capital impact (burned buildings and homes) accounted for $27.7 billion, 19 percent of the total; $32.2 billion, 22 percent of the whole, came from health effects of air pollution; and $88.6 billion in losses, 59 percent, was indirectly caused by the disruption of economic supply chains, including impediments to transportation and labor.

"When insurance companies, policy makers and even the media assess damage from California's wildfires, they focus on loss of life and direct destruction of physical infrastructure, which, while important, are not the whole picture," said co-author Steve Davis, UCI professor of Earth system science. "We tried to take a more holistic approach for this project by including a number of other factors such as the ill effects on the health of people living far away and the disruption of supply chains."

Climate change, land and fire management, population and economic growth, and increasing community encroachment in the wildland-urban interface have combined to increase the frequency and severity of wildfires in the Western United States over the past few decades, culminating in enormously damaging blazes in 2017, 2018 and 2020.

As the fires burned, satellite images showed trails of smoke spanning large areas of California, causing hazardous breathing conditions for residents of communities hundreds of miles from the burning fires.

Power transmission was affected by the fires, as was freight transport by rail and trucks, pipeline operations and many other business and infrastructure-dependent activities. The study showed that the majority of economic impacts were felt by industries and locations also far from the actual fires, and that nearly one-third of the total losses were outside of California.

"The broader impacts of these climate-driven wildfires are not only bigger than prior studies have estimated, but also more widely dispersed -- including sizable impacts outside of the state," lead author Dabo Guan, a Tsinghua University professor of Earth system science who is also a University College London researcher.

Davis said he hopes the study can help policy makers and fire managers make more sound decisions in the future about land and forest management, development patterns and fire suppression efforts. For example, the larger estimated costs may justify larger and different allocations of resources to fire prevention and suppression.

In particular, the authors suggest that disaster response teams may wish to focus "fire prevention efforts on areas typically upwind of major population centers or near important industrial or transportation infrastructure."

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