High-elevation forests threatened by climate change

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  High-elevation forests threatened by climate change

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Read more on - Polity | Economy | Schemes | S&T | Environment

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• The story: Nature has had its predictable patterns and cycles, now disrupted due to rapid rise in average global temparatures. Wildfires in the western United States are increasingly happening at high elevations, in mountainous areas that were previously too wet to burn.
• Drying them out: Global warming and ongoing drought conditions in the western U.S. are drying out such forests, making them particularly susceptible to blazes. With many Western states in US plunging deeper into a megadrought, and experts predicting a hot and dry summer, the research findings make for sombre reading.
• Learning from fires: Researchers examined records from 1984 to 2017 of all fires in the western U.S. that were larger than 1,000 acres, and found that the amount of scorched land increased across all elevations during that period, but observed that the biggest increase was at elevations above 8,200 feet.

1. The shift to higher-elevation fires was noticeable beginning in the year 2000. From 2001 to 2017, the area of land burned above 8,200 feet more than tripled compared to in the previous 16-year period, according to the study. For context, Aspen, Colorado, sits at an elevation of 8,000 feet above sea level.
2. Typically, at such high elevations, snow lingers through the summer, leaving little time for vegetation in these mountainous forests to dry out before rain and snow fall anew in the autumn and winter.
3. Now, global warming is melting mountain snowpack earlier in the year and disrupting that natural cycle.
4. There used to be a flammability barrier, where the forest was too wet to burn. With earlier snowmelt, vegetation has time to dry and so that flammability barrier is not there anymore for much of the western U.S.

• Data: More than 31,000 square miles of high-elevation forests — or roughly 11 percent of forest cover in the western U.S. — could be at risk this year and in future wildfire seasons. The new research focused on a 34-year period ending in 2017, the most recent year with reliable data available from the Monitoring Trends in Burn Severity program. During 2020's record-breaking fire season, for instance, several blazes in Colorado and California burned at high elevations.
• Deep impact: Scientists are concerned that wildfires in high-elevation forests could have worrisome consequences for the ecosystem. Climate change combined with longer and more intense wildfire seasons could alter the rate of snowmelt in these mountainous regions, which subsequently affects water that normally flows into reservoirs and rivers. Tree canopies that are lost in fires can also expose land and streams to more sunlight, which increases temperatures across elevations and could have negative implications for fish and other animals that live in these regions.
• Summary: The time to reverse emissions rapidly is now. The ecosystems are slowly edging towards a precipice.

Read more on - Polity | Economy | Schemes | S&T | Environment

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