During the current statistical period which runs from July through June wildfires in Chile have burned 601,367Ha (1.5 million acres) which is 924 percent of average for the entire 12-month period. That fact alone does not prove anything but it can trigger a need to look at the factors involved.
Below is an excerpt from an article in the Huffington Post:
Santiago, Chile and Los Angeles, California lie roughly the same distance from the equator and are subject to the same climatological forces. Both areas have endured years of record-breaking drought that has thinned forests and desiccated farms. In the summer heat, when winds pick up, fires can start easily and spread rapidly through dried vegetation.
For this, blame climate change. Heat-trapping carbon pollution is driving temperatures up across the globe, setting the conditions for severe heat, persistent dry spells and a high risk of fire. A recent study found that 25 percent of central Chile’s rainfall deficit could be attributed to human-caused climate change. Consistent with planetary warming, Chile is breaking heat records right and left. California is doing thesame.
In looking at the chart above, increased emissions of greenhouse gasses did not CAUSE the fires in Chile, but it is possible that their effects created an environment that made it possible for wildfires, once ignited, to spread more quickly than they would have otherwise, and were more resistant to control.
Changes in human uses of the land have had a large impact on fire activity in California’s Sierra Nevada since 1600, according to research by a University of Arizona researcher and her colleagues.
Above: Indian Canyon Fire near Edgemont, SD, 2016. Photo by Bill Gabbert.
By Mari N. Jensen, University of Arizona College of Science
Forest fire activity in California’s Sierra Nevada since 1600 has been influenced more by how humans used the land than by climate, according to new research led by University of Arizona and Penn State scientists.
For the years 1600 to 2015, the team found four periods, each lasting at least 55 years, where the frequency and extent of forest fires clearly differed from the time period before or after.
However, the shifts from one fire regime to another did not correspond to changes in temperature or moisture or other climate patterns until temperatures started rising in the 1980s.
“We were expecting to find climatic drivers,” said lead co-author Valerie Trouet, a UA associate professor of dendrochronology. “We didn’t find them.”
Instead, the team found the fire regimes corresponded to different types of human occupation and use of the land: the pre-settlement period to the Spanish colonial period; the colonial period to the California Gold Rush; the Gold Rush to the Smokey Bear/fire suppression period; and the Smokey Bear/fire suppression era to present.
“The fire regime shifts we see are linked to the land-use changes that took place at the same time,” Trouet said.
“We knew about the Smokey Bear effect — there had been a dramatic shift in the fire regime all over the Western U.S. with fire suppression. We didn’t know about these other earlier regimes,” she said. “It turns out humans — through land-use change — have been influencing and modulating fire for much longer than we anticipated.”
Above: Acres burned in the United States, 1986 through 2015. Data from NIFC, compiled by Bill Gabbert.
A new study released yesterday concludes that human-caused climate change is responsible for nearly doubling the number of acres burned in western United States wildfires during the last 30 years.
Fires in western forests began increasing abruptly in the 1980s, as measured by area burned, the number of large fires, and length of the fire season. The increases have continued, and recently scientists and public officials have in part blamed human-influenced climate change. The new study is perhaps the first to quantify that assertion. “A lot of people are throwing around the words climate change and fire–specifically, last year fire chiefs and the governor of California started calling this the ‘new normal,’ ” said lead author John Abatzoglou, a professor of geography at the University of Idaho. “We wanted to put some numbers on it.”
Warm air can hold more moisture. As the temperature rises the relative humidity decreases. Low humidity withdraws more moisture out of live and dead plants as well as soil. Plants are the fuel for wildfires and lower moisture means fires can burn more rapidly and with increased intensity and resistance to control. Average temperatures in forested parts of the U.S. West have gone up about 2.5 degrees F since 1970, and are expected to keep rising. The resulting drying effect is evident in the rise of more fires.
The overall increase in fire since the 1980s is about twice what the researchers attribute to climate change; the rest is due to other factors, they say. One has been a long-term natural climate oscillation over the Pacific Ocean that has steered storms away from the western United States. Another: firefighting itself. By constantly putting out fires, authorities have allowed areas they “saved” to build up more dry fuel, which later ignites, causing ever more catastrophic blazes, the researchers say. The costs of fire fighting have risen sharply in step; last year the federal government alone spent more than $2.1 billion. “We’re seeing the consequence of very successful fire suppression, except now it’s not that successful anymore,” said Abatzoglou.
The authors isolated the effects of climate warming from other factors by looking at eight different systems for rating forest aridity; these included the Palmer Drought Severity Index, the MacArthur Forest Fire Danger Index and the Canadian Forest Fire Danger Rating System. They then compared such measurements with observations of actual fires and large-scale climate models that estimate manmade warming. The crunched data showed that 55 percent of the increase in fuel aridity expected to lead to fires could be attributed to human-influenced climate change. Climate’s role in increasing such aridity has grown since 2000, the researchers say, and will continue to do so.
(The graphic below is from the study.)
The researchers found that anthropogenic climate change accounted for about 55% of observed increases in fuel aridity from 1979 to 2015 across western US forests, highlighting both anthropogenic climate change and natural climate variability as important contributors to increased wildfire potential in recent decades.
Mr. Abatzoglou and coauthor Park Williams, a bioclimatologist at Columbia University’s Lamont-Doherty Earth Observatory, say they do not account for some factors that could be offshoots of climate warming, and thus they may be understating the effect. These include millions of trees killed in recent years by beetles that prefer warmer weather, and declines in spring soil moisture brought on by earlier snowmelt. There is also evidence that lighting may increase with warming.
The study does not cover western grasslands. These have seen more fires too, but there is little evidence that climate plays a role there, said Mr. Abatzoglou; rather, the spread of highly flammable invasive grasses appears to be the main driver.
Mike Flannigan, a fire researcher at the University of Alberta, said that previous studies have tried to understand the effects of climate on fires in parts of Canada, but that nothing had been done for the United States on this scale. “What’s great about this paper is that it quantifies this effect, and it does it on a national scale,” he said.
Worldwide, wildfires of all kinds have been increasing, often with a suspected climate connection. Many see a huge fire that leveled part of the northern city of Fort McMurray, Alberta, this May as the result of a warming trend that is drying out northern forests. Fires have even been spreading beyond, into the tundra, in places where blazes have not been seen for thousands of years. That said, fires are not expected to increase everywhere. “Increased fire in a lot of places agrees with the projections,” said Jeremy Littell, a research ecologist with the U.S. Geological Survey in Anchorage, Alaska. “But in many woodlands, the relationship between climate and fire is not as tidy.”
Many scientists studying the issue believe the growth in U.S. western fires will continue for many years. Mr. Williams and others say that eventually, so many western forests will burn, they will become too fragmented for fires to spread easily, and the growth in fire will cease. But, he says, “there’s no hint we’re even getting close to that yet. I’d expect increases to proceed exponentially for at least the next few decades.” In the meantime, he said, “It means getting out of fire’s way. I’d definitely be worried about living in a forested area with only one road in and one road out.”
This is a rather surprising 2-minute video about attributing wildfires to climate change. It was produced by the National Center for Atmospheric Research and the University Corporation for Atmospheric Research.
“#ymmfire” refers to the airport code for the Fort McMurray International Airport in Alberta. The entire population of the city, more than 80,000, was ordered to evacuate when it became obvious it was going to be overrun by the fire.
Below is an excerpt from a May 4, 2016 article at Slate about the weather in Canada:
…Canada’s northern forests have been burning more frequently over recent decades as temperatures there are rising at twice the rate of the global average. A 2013 analysis showed that the boreal forests of Alaska and northern Canada are now burning at a rate unseen in at least the past 10,000 years. The extreme weather of recent months is also closely linked with the ongoing record-setting El Niño conditions in the Pacific Ocean, which tends to bring a warmer and drier winter to this part of Canada. Last month, Canadian officials mentioned the possibility of “large fires” after over-winter snowpack was 60 to 85 percent below normal and drought conditions worsened.
This week, a strong atmospheric blocking pattern—a semi-stable extreme arrangement of the jet stream—reinforced an unseasonable heat wave and helped temperatures reach 90 degrees Fahrenheit (32.2 degrees Celsius) on Tuesday in Fort McMurray, 40 degrees Fahrenheit above normal, eight degrees above the daily record high, 15 degrees warmer than Houston, and the same temperature as Miami. While fleeing, some evacuees had to turn on their air conditioners…
…Fires, once largely confined to a single season, have become a continual threat in some places, burning earlier and later in the year, in the United States and abroad. They have ignited in the West during the winter and well into the fall, have arrived earlier than ever in Canada and have burned without interruption in Australia for almost 12 months.
A leading culprit is climate change. Drier winters mean less moisture on the land, and warmer springs are pulling the moisture into the air more quickly, turning shrub, brush and grass into kindling. Decades of aggressive policies that called for fires to be put out as quickly as they started have also aggravated the problem. Today’s forests are not just parched; they are overgrown.
In some areas, “we now have year-round fire seasons, and you can say it couldn’t get worse than that,” said Matt Jolly, a research ecologist for theUnited States Forest Service. “We expect from the changes that it can get worse.”…