Linking wildfires to climate change — it’s complicated

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.

Tuesday’s weather in Fort McMurray was 8 degrees above record high for the date

Hot weather Alberta

“#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.

More information about 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…

New York Times: wildfire seasons are longer

Yesterday the New York Times published an article titled, “Wildfires, Once Confined to a Season, Burn Earlier and Longer”.

Here is an excerpt:

…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.”…

British Columbia using assisted migration to help forests keep up with climate change

range of Western Larch
The range of Western Larch, Larix occidentalis, sometimes called Western tamarack. From Natural Resources Canada.

Warming caused by climate change is moving the suitable habitat for some plant species farther north in the northern hemisphere. A plant that was once comfortable in one location may be finding it is becoming too warm for it to thrive.

British Columbia, unlike the other Canadian provinces, has changed their rules about replanting forests, hoping to ensure that adapted tree varieties can keep up with the moving habitats. Critics say assisted migration, as it is called, has sometimes produced disastrous results in the past when species were placed in new environments.

Western larch
Western Larch, a deciduous conifer. Photo from Montana Outdoors.

Vice’s Motherboard web site has a fascinating article by Stephen Buranyi on the subject. Here is an excerpt:

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“The Western Larch can live for hundreds of years and grow to over 200 feet, but the oldest Larch trees in northern British Columbia’s Bulkley Valley are only about four feet tall. In fact, the nearest full grown Western Larch is nearly 900 kilometers south by the US border, which has been the Larch’s natural range for thousands of years. These are the first trees of their kind to be planted so far north.

If the disastrous history of invasive species has taught us anything, it’s that it’s often difficult to predict the consequences of such a change. Ecologists and conservationists generally caution against moving a species outside of the areas they naturally live—a process known as assisted migration—and governments generally agree with this take. Across North America there are strict prohibitions against the large scale movement of living populations.

But for the past seven years the province of BC has allowed millions of trees to be planted toward the northernmost reaches of their natural range and beyond. The government is working with scientists who predict that our climate is changing so quickly that, 50 years from now, when the trees are fully grown, the conditions in the trees’ new homes will actually be more like their old ones.

“It restores the tree to the environment for which they are best suited,” said Greg O’Neill, an adaptation and climate change scientist with the BC government, who helped design and implement the province’s assisted migration program. But while BC scientists think that they’ve acted just in time to prepare their forests for the future, no other province appears ready to adopt assisted migration as a strategy anytime soon.

Many trees are what ecologists call foundational species—organisms whose removal would cause enormous disruption in the ecosystem. Trees are a sort of infrastructure for forests; they bind the soil, retain water, and provide food and shelter. Just like the infrastructure unpinning cities, it takes years to establish a tree population, and they are virtually impossible to move.

And yet, because BC’s northern regions are warming at nearly twice the average rate, much of the province’s 55 million hectares of forest may find that their homes have moved north without them. A 2006 paper from the University of British Columbia applied a climate based model to forest ecosystems and showed that some species ranges could shift by up to 100 kilometers each decade.

Rules in BC require that, as trees are cut down, planters use seeds from the same area to re-plant, preserving the genetic character of the forest. O’Neill and his colleagues produced a forestry report in 2008 that drew on the projected range expansions due to climate change, and their own extensive experiments testing various tree species in different climates. They suggested that the province instead expand the distance seeds could be moved uphill, to track with global warming. Later that year the Chief Forester’s Standards for Seed Use were changed for the majority of BC’s commercial tree species to reflect the suggestions in the report.

According to O’Neill, “these were the first policy changes that addressed climate change in forestry.”

Then, in 2010 the standards were changed again, to allow Western Larch to be planted hundreds of kilometres away from its current range. “That had been a long-standing paradigm that no-one dared transgress,” said O’Neill. One ecologist had even called BC’s migration plans “a little scary.”

It’s difficult to overstate how deeply rooted the aversion to moving nature is for many biologists. In 2009 assisted migration was called “planned invasion” in a report that listed our really awful, truly just stupendously bad track record with species that unexpectedly turn invasive…”

Was the 2014 wildfire season in California affected by climate change?

Happy Camp Complex, 2014
Happy Camp Complex in northern California in 2014. Photo by Kari Greer.

2014 was a busy year in California for wildland firefighters. Battles were fought over 555,044 acres of blackened ground in the state, which was the eighth largest number of acres burned in the last 28 years. So far in 2015, fires have covered 838,465 acres in California, which puts it fifth highest in 28 years.  (Stats from Cal FIRE and the NIFC National Situation Report.)

We have always been dubious of linkages between one weather event and long term climate change. When a senator brings a snowball onto the Senate floor or a governor talks about this summer’s fires to prove their cases that climate change does or does not exist, both may be over stating their “evidence”.

However, I’m not a meteorologist or climate scientist. But some of them who are, took a stab at investigating the possible attribution of extreme weather-related events in 2014 to global climate change. In their report, Explaining Extreme Events of 2014 from a Climate Perspective33 different research groups explored the causes of 29 different events that occurred that year.

The first event in the report is titled, Extreme Fire Season in California: A Glimpse Into the Future. It is debatable if the 2014 fire season in California was “extreme”, since like we wrote earlier, it had the eighth largest number of acres burned in the last 28 years according to data from the land management agencies. The authors, Jin-Ho Yoon, S.-Y. Simon Wang, Robert R. Gillies, Lawrence Hipps, Ben Kravitz, and Philip J. Rasch, reported “thousands more fires than the five-year average” between January 1 and September 20.

We don’t put very much stock in numbers of fires, since a small spot that can be stomped out by a couple of firefighters counts just as much as a 300,000-acre conflagration. Total burned acres is much more meaningful. The area burned data that the scientists studied was derived from satellite observations, which can underestimate wildfire extent due to its limit in the minimum detectable burned area, timing of the satellite overflights, light fuels cooling before being detected, and obscuration by cloud cover.

The report also examined the Keetch-Byram Drought index, and determined that “in terms of the KBDI and the extreme fire risk, 2014 ranks first in the entire state”, but it was not clear what time period they were referring to (it may have been since 1979).

The authors fall short of attributing the “extreme” 2014 fire season in California to global climate change:

Our result, based on the CESM1 outputs, indicates that man-made global warming is likely one of the causes that will exacerbate the areal extent and frequency of extreme fire risk, though the influence of internal climate variability on the 2014 and the future fire season is difficult to ascertain.

2014 climate events
Location and types of events analyzed in the publication. The image is from the study.