This study has confirmed what westerners have long feared: wildfires have become intense, larger, and burning areas upslope in the region's mountainous areas that have not burned before. These areas have always been moist areas that are changing much too fast for comfort.
NASA has found a new connection between burning mountains and climate change. Since the west counts on snowfall for potable water, the study should alarm decision-makers across the world. Not only is global warming increasing snowmelt, but the heat generated is drying up vegetation providing tinder for fires to cross mountain ranges.
Researchers found that since 1984 when Landsat images became available high elevation fires have moved upslope by 25 feet a year while dryer air has moved 29 feet per year.
Historically, forest fires have been rare in high-elevation areas—at least 8,200 feet (2,500 meters) above sea level. But when McGill University scientist Mohammad Reza Alizadeh and colleagues studied fires that occurred in the West between 1984 and 2017, they found blazes moving to higher ground at a rate of 25 feet (7.6 meters) per year.
Fires are now burning higher up on hillsides and mountainsides because areas that used to be too wet to burn are now drier due to warmer temperatures and earlier snowmelt. The study also showed that drier air—which makes vegetation dry out and burn more easily—is moving upward at a rate of about 29 feet (8.9 meters) each year. The researchers estimated that an additional 31,500 square miles (81,500 square kilometers) of the mountainous U.S. West are now more vulnerable to fires compared to 1984.
The impacts of such high-elevation fires are numerous. Many mountain ranges serve as “water towers” for the western U.S.: snow accumulates on mountaintops each winter and then melts and runs down to river valleys as a summer water source. Fires can change how snow accumulates and melts, shifting when it is available in downstream reservoirs and rivers. That’s a problem for more than 60 million people in the western US who rely on this water source. Fire debris, ash, and chemical retardants also can pollute the water, reducing its quality for drinking.
High-elevation fires are also bad news for species native to those areas because the much of the plant life is not fire-adapted and may grow back differently, as a 2020 paper suggested. Streams near high-elevation fires can also become much warmer than those in similar areas without fires. Both conditions threaten native animals and plants that depend on cooler water and air.
Finally, many towns and cities located at high elevations are not necessarily accustomed to the threat of wildfires. “Areas in Canada and the western U.S. are experiencing droughts and heat waves, which increase the risk of fires,” said Mojtaba Sadegh, an assistant professor at Boise State University and a co-author of the paper. “This should raise the alarm for people to think more about what the future will look like if global warming continues at the same rate.”
The research was only possible by Landsat satellite images. The images provide data that scientists can analyze the many perils of our rapidly changing world.
The ash generated by these firestorms threatens water supplies in the west with contaminates on forest streams and lakes. The vegetation surrounding these mountain water sources, once burned, no longer keeps the soil in place or retains water.
The ash also falls on one of our two critical climate airconditioners, the Greenland Ice Sheet. The dark surface of the ice partially from falling ash accelerates the melting of the ice cap as there is no longer white ice to reflect solar energy to space.
Yale Environment 360 writes on the consequences of Ash and fire scars on mountains aquatic systems — How Wildfires Are Polluting Rivers and Threatening Water Supplies
Cameron Falls in Canada’s Waterton Lakes National Park runs cold and clear in summer, when as many as a half-million people come to canoe, fish, hike, and bike in this pristine Rocky Mountain landscape along the Alberta/Montana border. On very rare occasions, it runs a Pepto Bismol pink when heavy rains stir up argillite, a red mudstone that is found upstream. But on June 21, residents, tourists, and park officials were shocked to see the waterfalls suddenly running pitch black. Heavy rain had flushed in soot, ash, and charred tree debris from a fire that burned most of the 195-square-mile park the year before.
When it happened again a few weeks later following another violent rainstorm, the dark flow of mountain water rushed in with such ferocity that it piled charred branches and debris into the gorge, a neighboring parking lot, and a street of a community inside the park. The 2017 blaze had been so intense that at one point it danced and swirled 16 miles from one end of the park to the other in less than eight hours. So much of the park had burned that officials initially closed nearly 80 percent of the backcountry trails.
As hotter and dryer conditions spawn an increasing number of wildfires in North America and around the world, one of the overlooked impacts of these worsening conflagrations is on aquatic environments and drinking water supplies. Just as wildfires can have a regenerative effect on woodlands, so, too, can fires provide some benefits to streams and rivers in burned areas. But scientists are warning that intense and repeated fires can damage the ecology of waterways by exposing them to the sun’s heat, exacerbating flooding and erosion along denuded hillsides, and releasing toxins such as mercury that are often liberated from soil and tree trunks.
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